Restoration of the Paleocene-Miocene nautiloid cephalopod Aturia
Fossilized fronds of the Carboniferous-Early Cretaceous seed fern Alethopteris
Fossils of the Ordovician-Permian bryozoan Amplexopora
Fossil of the Carboniferous horsetail relative Annularia
Fossil of the Carboniferous horsetail relative Annularia
Restoration of the face of the Carboniferous reptiliomorph Anthracosaurus
Illustration of Anthracosaurus fossils including a skull pictured from above (left), a cross section of a tooth (upper right), and tooth itself (lower right)
Restoration of the Carboniferous synapsid (mammal precursor) Archaeothyris
Restoration of the Carboniferous synapsid (mammal precursor) Archaeothyris
Reconstructed cranium of the Carboniferous synapsid (mammal precursor) Archaeothyris
Fossilized shell of the Silurian-Late Devonian brachiopod Atrypa reticularis
Mold fossil of a shell of the Early Devonian-Late Triassic bivalve Aviculopecten
Fossil of the Late Ordovician-Permian tabulate coral Aulopora
Fossilized shell of the Early Cretaceous-Oligocene turtle Adocus
Restoration of the Cretaceous-Pleistocene amphibian Albanerpeton
Fossilized skeleton of the tyrannosaur Albertosaurus
Restoration of the Late Jurassic theropod dinosaur Allosaurus
Fossilized skull of the Late Jurassic crocodile relative Amphicotylus
Fossil (right) of the Early Jurassic dinosaur footprint ichnogenus Anomoepus
Upper view of the pelvis of the Late Jurassic sauropod dinosaur Atlantosaurus. This genus is now regarded as being of dubious validity and possibly the same as Apatosaurus.
Fossilized shell of the Late Ordovician-Carboniferous brachiopod Atrypa
Fossilized skull of the Miocene saber-toothed cat Amphimachairodus
Fossils of the mysterious Ediacaran organism AspidellaFossil of the mysterious Ediacaran organism AspidellaFossils of the mysterious Ediacaran organism AspidellaDiagram depicting the soft part anatomy of the sea snail AbyssochrysosFossilized teeth of the Permian-Paleocene cartilaginous fish AcrodusRestoration of the Late Cretaceous armored dinosaur AletopeltaShell of an Amauropsis moon sea snailShell of an Architectonica staircase shell sea snailShell of an Architectonica staircase shell sea snailFossilized shell in multiple views of an Architectonica staircase shell sea snailRear side of a fossilized shell of the Late Cretaceous-modern brachiopod ArgyrothecaIllustration of a larva of the Late Cretaceous-modern brachiopod ArgyrothecaFossilized shell of the Early Jurassic ammonoid cephalopod AsterocerasFossilized partial skull of the Late Cretaceous duck-billed dinosaur AugustynolophusIllustration of a living Acipenser medirostris, or green sturgeonA living Acmaea mitra, or whitecap limpetFossilized skeleton of the Miocene horse AcritohippusA living Actinemys marmorata, or western pond turtleA living Aechmophorus occidentalis, or western grebeFossilized skull of the Miocene bone-crushing dog AelurodonRestoration of the Miocene camel Aepycamelus, or the long-necked camel. Heinrich Harder (1920).Fossilized shell of the Triassic-modern scallop AequipectenA living AgelaiusFoliage and fruits of an Ailanthus treeRestorative model of the Miocene deer relative AletomeryxCaught Alopias vulpinus, or common thresherShells in multiple views of Alvania sea snailsIllustration of a shell of Amauropsis moon sea snailsFlowers and foliage of Amelanchier, or shadbushClose-up view of the flowers of Amorpha fruticosa, or desert false indigoRestoration of the Miocene-Pliocene beardog AmphicyonCollection of Anadara marine ark clamsA living Mareca americana (formerly Anas americana), or American wigeonA living Spatula clypeata, or northern shovelerFossilized limb bones, and teeth of the Miocene three-toed horse Anchitherium (left)A living Anniella, or American legless lizardA living Anser albifrons, or greater white-fronted gooseA living Antilocapra, or pronghornA colony of roosting Antrozous pallidus, or pallid batsA living Aphelocoma californica, or California scrub jayReconstructed skeleton of the Miocene-Pleistocene hornless rhinoceros AphelopsA living Aquila chrysaetos, or golden eagleBranch with foliage and fruit of a living Arbutus, or madronaFossilized skull of the Oligocene bone-crushing dog ArchaeocyonIllustration of a living Archoplites interruptus, or Sacramento perchLiving Arctocephalus fur sealsShells of Argopecten gibbus, or Atlantic calico scallopsA modern Argyropelecus silver hatchetfishA living Asio otus, or long-eared owlA living Astropecten sea starA living Athene cunicularia, or burrowing owlFossilized skull of the Miocene dolphin AtocetusRestoration of the Miocene sperm whale AulophyseterRestoration of the Middle-Late Ordovician jawless fish AstraspisA living Abies, or fir treeA living Acalles weevilA living Acris, or cricket frogLiving Acrostichum, or leather fernsA living Agrilus jewel beetleA living Agriotes click beetleBranches and fruits of an Aleurites treeRestoration of the crocodilian AllognathosuchusA living Altica flea beetleA living Amblyteles parasitic waspRestoration of the Miocene elephant relative Amebelodon. Margret Flinsch (1932).A living Anabrus , or Mormon cricketFossilized limb bones, jaws and teeth of the Miocene three-toed horse Merychippus (left)A living Andrias giant salamanderFossilized tooth of the Oligocene-Miocene shark Carcharocles angustidensA living Anthaxia jewel beetleA living Anthidium, or carder beeA living Anthomyia flyA living Anthonomus weevilFossil of the Eocene ant Aphaenogaster mayriA living Aphodius scarab beetleA living Aphrophora spittlebugA living Araneus orb-weaving spiderRestoration of the Eocene-Oligocene entelodont mammal ArchaeotheriumFossil of the Eocene ant ArchimyrmexRestoration of the Paleocene mammal ArctocyonA living Argia damselflyFlower of a living Aristolochia, or birthwortFruit and foliage of an Asimina tree, or pawpawA living Astronium tree, which is related to cashewsA living Athous click beetleA living Aythya americana, or redheadFossilized teeth of the Pliocene-Pleistocene rabbit relative AztlanolagusRestoration of the Early Jurassic sauropodomorph dinosaur AnchisaurusFossilized skeleton of the Late Cretaceous bony fish ApsopelixFossilized mandibles of the Miocene three-toed horse AnchitheriumClosed and open shell of Abra marine bivalvesLiving Acropora cervicornis, or staghorn coralShells of Acteocina barrel-bubble sea snailsA living Actitis macularius, or spotted sandpiperA living Aetobatus narinari, or spotted eagle rayA living Agelaius phoeniceus, or red-winged blackbirdClose-up portrait of a living Agkistrodon piscivorus, also known as a water moccasin or cottonmouthA living Aix sponsa, or wood duckA living Platalea ajaja (sometimes Ajaja ajaja), or roseate spoonbillA living Alligator mississippiensis, or American alligatorLiving Alveopora stony coralA living Amia, or bowfinA living Ammodramus maritima, or seaside sparrowA living Amphiuma means, or two-toed amphiumaShell of an Anachis dove sea snailShell of an Anadara floridana, or cut-ribbed ark clamShell of an Anadara transversa, or transverse ark clamA living Anas carolinensis, or green-winged tealA living Spatula cyanoptera, or cinnamon tealA living Anas rubripes, or American black duckA living Anhinga, also known as a snakebird or darterShell of an Anodonta river musselShell of an Anomia simplex, or the common jingle shellShell of an Antillophos nassa mud snailA living Apalone ferox, or Florida softshell turtleA living Aphelocoma coerulescens, or Florida scrub jayA living Arbacia sea urchinInterior of the shell of an Arca zebra, or turkey wing ark clamA living Archosargus probatocephalus, or sheepsheadShells of Arcinella arcinella, or Caribbean spiny jewel box clamsA living Ardea herodias, or great blue heronA living Ardeola, or pond heronA living Argopecten irradians (formerly Aequipecten irradians), or Atlantic bay scallopA living Asio flammeus, or Short-eared owlShell of an Assiminea snailShell in multiple views of an Astralium, or star sea snailShell of a Lithopoma phoebium (formerly Astraea phoebia), or longspine star shell sea snail, inhabited by a hermit crabFossil of the Cambrian trilobite AsaphiscusRestoration of the Late Cretaceous tyrannosaur AlbertosaurusInterior of the shell of an Arca ark clamA living AmphiumaShell in multiple views of an Anadara brasiliana, or incongruous ark clamElectron micrograph and gross view of an Astrangia poculata stony coral
Assemblage of fossils of the Cambrian trilobite AgnostusRestoration in enrolled posture of the Cambrian trilobite AgnostusLiving Abies, or fir treesFossilized fronds of the Carboniferous-Early Cretaceous seed fern AlethopterisRestoration of the Carboniferous amphibian AmphibamusIllustration of a fossil of the Carboniferous pill millipede AmynilyspesFossilized foliage of the Late Devonian-Carboniferous tree ArchaeopterisRestoration of the Late Devonian-Carboniferous tree Archaeopteris with insets detailing its anatomyRestored foliage of the Late Devonian-Carboniferous tree ArchaeopterisIllustration of a fossil of the Carboniferous-Permian spider Arthrolycosa. Charles Emerson Beecher (1889).Fossilized calyx of the Carboniferous crinoid ("sea lily") AbrotocrinusFossilized calyx and partial stem of the Devonian-Permian crinoid ("sea lily") ActinocrinitesFossilized calyx and partial stem of the Carboniferous crinoid ("sea lily") AgaricocrinusFossilized calyx of the Carboniferous crinoid ("sea lily") Agaricocrinus americanus, or the mushroom crinoidFossilized stem of the Carboniferous crinoid ("sea lily") Agaricocrinus americanus, or the mushroom crinoidLife restoration of the Early Devonian club moss relative AsteroxylonRestoration of the Early Devonian-Permian "spiny shark" AcanthodesFossilized skeleton of the Early Devonian-Permian "spiny shark" AcanthodesLife restoration of the Carboniferous synapsid (mammal precursor) ArchaeovenatorFossilized shell of the Late Cretaceous ammonoid cephalopod AcanthoscaphitesIllustration of a partial fossilized pelvis of the Late Cretaceous bird ApatornisA living Anaxyrus cognatus (formerly Bufo cognatus), or Great Plains toadFossilized dorsal fin-spine of the Devonian-Cretaceous shark AsteracanthusFossilized teeth of the Devonian-Cretaceous shark AsteracanthusShells of Acirsa wentletrap sea snailsA living Ammospermophilus, or antelope squirrelA living Ariosoma conger eelLife restoration of the Early Cretaceous theropod dinosaur AcrocanthosaurusFossilized skeleton of the Late Cretaceous-Oligocene Alligator relative AllognathosuchusAssemblage of fossilized skeletons of the softshell turtle AmydaRestoration of the Early Cretaceous sauropod dinosaur AstrodonIllustration of a living Acipenser sturgeonLiving Acropora palmata, or elkhorn coralFossilized skull of the Miocene baleen whale AglaocetusA living Asterias forbesi, or Forbes sea starRestoration of the Miocene stargazer Astroscopus countermaniFossil of the Cambrian trilobite AgraulosDiagram illustrating the Early Jurassic sauropodomorph dinosaur Anchisaurus with an anachronistic human to scaleA living Abies balsamea, or balsam firFossilized skeleton of the gar AtractosteusRestoration of the Late Ordovician nautiloid cephalopod Aphetoceras being preyed upon by a CamerocerasFossilized skeleton of the Carboniferous lobe-finned fish AllenypterusRestoration of the Carboniferous lobe-finned fish AllenypterusRestoration of the Late Cretaceous horned dinosaur AchelousaurusRestoration of the Late Cretaceous dromaeosaurid ("raptor") AcheroraptorFossilized skull of the Late Cretaceous duck-billed dinosaur AcristavusRestoration of the Late Cretaceous horned dinosaur AlbertaceratopsRestorative model of the Late Cretaceous mammal AlphadonRestoration of the Late Cretaceous armored dinosaur AnkylosaurusRestoration of the Early Cretaceous primitive horned dinosaur AquilopsRestoration of the Late Cretaceous horned dinosaur AvaceratopsRestoration of the Late Cretaceous toothed bird Avisaurus perched on a crocodilianLife restoration of the Eocene-Oligocene even-toed ungulate AgriochoerusLiving Araucaria treesLiving Azolla water fernsIllustration of a living Aplodinotus grunniens, or freshwater drumDiagram of a restored biramous leg of the Cambrian trilobite AgnostusFossil of the Cambrian arthropod AnomalocarisRestoration of the Cambrian arthropod AnomalocarisDiagram illustrating the Cambrian arthropod Anomalocaris with an anachronistic human to scaleFossilized grasping claw of the Cambrian arthropod AnomalocarisRestorative model of the Cambrian arthropod AnomalocarisFossilized mouthpart of the Cambrian arthropod AnomalocarisFossilized shell of the Early Jurassic ammonoid cephalopod AlsatitesFossil of the Ordovician-Modern sea star trace fossil ichnogenus AsteriacitesFossilized skull and partial neck of the Middle Triassic plesiosaur relative AugustasaurusRestoration of the Middle Triassic plesiosaur relative AugustasaurusFossilized skeleton of the Early Cretaceous-Oligocene turtle Adocus beatusMap of fossil trackways including (green) those of the Early Jurassic dinosaur footprint ichnogenus AnomoepusFossilized skeleton of the gar AtractosteusFossils of the gar AtractosteusFossil of the Early Devonian-Permian eurypterid ("sea scorpion") AdelophthalmusFossils of the Early Devonian-Permian eurypterid ("sea scorpion") AdelophthalmusRestoration of the Permian synapsid (mammal precursor) AerosaurusIllustration of a fossilized skull of the Permian synapsid (mammal precursor) AerosaurusLife restoration of the Carboniferous amphibian AnconastesDiagram illustrating the sizes of three specimens of the Late Cretaceous long-necked dinosaur Alamosaurus, with an anachronistic human to scaleFossilized skull of the Late Triassic phytosaur AngistorhinusA living Accipiter hawkFossilized scutes of the Paleocene Alligator relative AkanthosuchusRestoration of the Paleocene mesonychid mammal Ankalagon saurognathus (top)Restoration of the Paleocene mesonychid mammal Ankalagon saurognathus (top)A living Aythya duckFossilized teeth (W) of the Cambrian–Early Ordovician conodont AcanthodusFossilized teeth of the Cambrian–Early Ordovician conodont AcanthodusIllustration of fossils of the Cambrian trilobite AcidiscusIllustration of fossils of the Cambrian trilobite AcimetopusFossil of the Silurian-Early Devonian eurypterid ("sea scorpion") AcutiramusLife restoration of the Silurian-Early Devonian eurypterid ("sea scorpion") AcutiramusIllustration of fossils of the Cambrian trilobite AnaloxFossil of the Early-Middle Ordovician trilobite AsaphusRestoration of the Middle Devonian arachnid AttercopusA living Acanthocybium solandri, or wahooA living Actinocyclus sea slugA living Alca, or razorbillA living Alopias superciliosus, or bigeye thresherA living Aluterus filefishIllustration of a living AmmodytesA living Anisotremus gruntA living Apalone softshell turtleShells of Arcinella jewel box clamsA living Ardea cinerea, or grey heronReconstructed skeleton of the Late Triassic Aetosaurus. Othniel Charles Marsh (1895).Restorative model of the Late Cretaceous marsupial relative AlphadonRestoration of the Late Cretaceous oviraptorosaur AnzuFossilized skeleton of the Late Cretaceous sea turtle ArchelonRestoration of the Permian amphibian AchelomaFossilized skeleton of the Permian amphibian AchelomaIllustration of a reconstructed skull and restoration of the head of the Permian primitive reptile AcleistorhinusIllustration of a fossilized skull in multiple views of the Permian primitive reptile AcleistorhinusShell of an Acamptogenotia sea snailShell of an Acmaea sea snailFoliage and flowers of a living ActinidiaRestoration of the Oligocene baleen whale AetiocetusRestoration with insets detailing the anatomy of the Oligocene alder tree Alnus heterodontaLeaf and other anatomical components of a living Anamirta vineRestoration of the Late Devonian-Carboniferous tree Archaeopteris macilenta with insets detailing its anatomyFossil of the Cambrian trilobite AsaphiscusRestorative portrait of the Permian synapsid (mammal precursor) ApsisaurusLife restoration of the Permian reptile AraeoscelisRestoration of the Permian reptile Araeoscelis. Samuel Wendell Williston (1914).Restoration of the Permian amphibian ArcheriaLife restoration of the Permian amphibian ArcheriaFossilized shell of the Early-Late Cretaceous ammonoid cephalopod AcanthocerasFossilized shell of the Late Cretaceous ammonoid cephalopod AcompsocerasRestoration of the Late Triassic synapsid (mammal precursor) AdelobasileusRestoration of the Late Cretaceous horned dinosaur AgujaceratopsShells in differing orientations of Akera sea haresShell of an Ancilla sea snailReconstruction of a fossilized skull of the Late Cretaceous duck-billed dinosaur AngulomastacatorFossilized shell of the Late Jurassic-Early Cretaceous ammonoid cephalopod AspidocerasLife restoration of the Early Cretaceous long-necked dinosaur AstrodonFossilized skeleton of the Oligocene Alligator prenasalisShell of an Ancilla olive sea snailA living Aegolius funereus, or boreal owlA living Acris crepitans, or northern cricket frogFossilized skeleton of the Eocene pig-nosed turtle AllaeochelysFossilized forelimbs of the Miocene Alligator olseni, or Olsen’s AlligatorLife resoration of the Miocene-Pleistocene elephant relative AnancusFossilized partial mandible of the Eocene-Oligocene bear dog AngelarctocyonModern fruit, whole and in cross-section of an Annona treeFossil of the Cambrian velvet worm relative AysheaiaFossilized skeleton of the Cretaceous armored dinosaur AnimantarxIllustration of fossilized teeth from the Late Cretaceous tyrannosaur AublysodonFossilized shell of the Eocene-Oligocene turtle AnosteiraFlowers and foliage of a living AcaciaA living Accipiter gentilis, or northern goshawkFossilized needles of an Amentotaxus, or catkin-yewA living Anobium beetleFruit and foliage of a living Artocarpus, the genus including bread and jackfruitA living Aythya collaris, or ring-necked duckA living Antigone canadensis (formerly Antigone canadensis), or sandhill craneA living Agkistrodon contortrix, or copperheadA living Ambystoma jeffersonianum, or Jefferson salamanderRestoration of the Cambrian arthropod AglaspisIllustration of a living Agathidium round fungus beetleFossil of the Triassic-Jurassic crustacean AntrimposFoliage and cones of a living Araucaria treeFossilized cone of the Triassic-modern tree AraucariaShell of a living Anguispira alternata land snail, or flamed tigersnailA living Anoxypristis cuspidata, or knifetooth sawfishLiving Amphibalanus improvisus, or bay barnacles encrusting a bivalve shellShell of a modern Astarte bivalve
Fossilized shell of the Silurian-Early Triassic mollusc Bellerophon
Life restorationg of the Carboniferous amphibian Brachydectes
Reconstructed skull of Brachydectes in multiple views; complete skull viewed from right side (top), cranium viewed from above (middle), and cranium viewed from below (bottom)
Restoration of the Carboniferous amphibian Brachydectes
Fossilized shell in multiple views of a Busycon sea snail
Segment of a fossilized shell of the Late Cretaceous ammonoid cephalopod Baculites
Segment of a fossilized shell of the Late Cretaceous ammonoid cephalopod Baculites showing sutures and remnant aragonite
Segment of a fossilized shell of the Late Cretaceous ammonoid cephalopod Baculites. The original aragonite of the outer shell and inner chamber walls has dissolved away, leaving this articulated internal mold.
Mummified specimen found in Alaska of the Pleistocene-Holocene Bison priscus, or steppe bison. This specimen, known as "Blue Babe" after the blue ox of Paul Bunyan folklore, derives its unusual coloration from a chemical reaction between the phosphorus in its skin and iron in the surrounding soil to produce a coating of vivianite.
Fossilized skeleton of the Pleistocene-Holocene bovid Bootherium bombifrons, or Harlan's musk ox.
Fossil slab and counterslab of the bony fish Boreosomus
Fossil of the Silurian trilobite BalizomaFossil of the sauropod dinosaur footprint ichnogenus BrontopodusRestoration of the Eocene whale BasilosaurusFossil of the Cambrian trilobite BristoliaMold fossil of a head of the Cambrian trilobite BristoliaRestoration of the Early Ordovician-Silurian trilobite BumastusSegment of the fossilized shell of the Late Cretaceous ammonoid cephalopod BaculitesShell of a Barbatia, or bearded ark clamFossilized skeleton of the Cretaceous turtle BasilemysFossilized shell of the Late Cretaceous ammonoid cephalopod BostrychocerasShell of a Bulimulus land snailA living Bullina bubble sea snailA living Balaenoptera physalus, or fin whaleFossilized skeleton of the Pliocene whale BalaenulaLiving Balanophyllia elegans stony coralFossilized skull of the Miocene-Pliocene false saber-toothed cat BarbourofelisA living Bassariscus astutus (left), or ringtailA living Beringraja binoculata, or big skate
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Fossilized skeleton of the eocene-?Miocene boa snake BoavusRestoration of the Miocene grenadier fish Bolbocara (bottom)Illustration of a living Borophryne apogon, or netdevilRestorative portrait of the Miocene oreodont mammal BrachycrusA living Brachyramphus murreletA living Branta bernicla, or black brantA living Bubo virginianus, or great horned owlA living Bucephala albeola, or buffleheadShells in multiple views of Bulla gouldiana, or the California bubble sea snailA living Buteo jamaicensis, or red-tailed hawkA living Buteo swainsoni, or Swainson's hawk.Fossilized skeleton of the Paleocene-Eocene pantodont mammal BarylambdaLife restoration of the Paleocene-Eocene pantodont mammal BarylambdaRestoration of the Eocene uintathere mammal Bathyopsis being hunted by mesonychidsFossilized cranium of the Eocene uintathere mammal BathyopsisFossilized skeleton of the Late Cretaceous-Eocene crocodilian BorealosuchusSkeletal reconstruction of the Eocene-Oligocene bear-dog BrachyrhynchocyonA living Bruchus leaf beetleA living Buteo hawkRestoration of the Late Cretaceous bony fish Bonnerichthys with an anachronistic scuba diver to scaleA living Bairdiella chrysoura, or American silver perchIllustration of a living Balaenoptera acutorostrata, or common minke whaleLiving Balanus trigonus barnaclesA living Balistes triggerfishShells of Batillaria mudcreeper snailsBerries of a living Lindera melissifolia (formerly Benzoin melissifolium), also known as pondberry or southern spicebushShell in side view (top) and bottom view of Biomphalaria havanensis, or the ghost rams-hornFossilized skeleton of the Pleistocene Bison latifrons, also known as the giant bison or long-horned bisonA living Blarina carolinensis, or southern short-tailed shrewA living Blarina brevicauda, or northern short-tailed shrewRestoration of the Miocene musk deer Blastomeryx. Robert Bruce Horsfall (1913).A living Boa constrictorUnderside of a fossilized cranium of the Eocene anthracothere mammal BothriodonShell of a Brachycythara sea snailLiving male (left) and female (right) Anaxyrus quercicus, or oak toadsA living Anaxyrus fowleri (formerly Bufo fowleri), or Fowler's toadA living Bulimulus land snailShell of a Bursa rugosa frog shell sea snailShell in multiple views of a Busycon contrarium whelkShell in multiple views of a Busycon carica, or knobbed whelkShell in multiple views of a Sinistrofulgur perversumA living Buteo lineatus, or red-shouldered hawkA living Buteo platypterus, or broad-winged hawkA living Butorides virescens, or green heronDiagram illustrating the Eocene whale Basilosaurus with an anachronistic human to scaleA living Bison bisonFossilized skull of the Miocene-Pliocene bone-crushing dog BorophagusFossil of the Early Ordovician-Silurian trilobite BumastusIllustration of a fossil of the Early Ordovician-Silurian trilobite BumastusReconstruction (left) of a fossil (right) of the Ordovician sea urchin Bothriocidaris. The short spines which were attached to the tubercles are not drawn.Restoration of the Carboniferous Chimaera relative BelantseaLiving Botryococcus green algaeIllustration of a living Belone needlefishShell in multiple views of a Bittium cerith sea snailIllustration of a living Bregmaceros, or codletShell of a Bullia nassa mud sea snailPreserved specimen of Buccinum undatum, or the common whelk sea snailPortrait of a living Balaenoptera baleen whaleA living Brevoortia tyrannus, or Atlantic menhadenIllustration of a living Batrachoides toadfishDiagram of the known fossil material of the Late Cretaceous dromaeosaurid ("raptor") BambiraptorRestoration of the Late Cretaceous horned dinosaur BrachyceratopsRestoration of the Late Cretaceous Alligator relative BrachychampsaFossilized natural mummy of the Late Cretaceous duck-billed dinosaur BrachylophosaurusShoot and flowers of a modern Berberis, or barberryIllustration of a fossil of the Cambrian trilobite BathynotusRestoration of the Cambrian trilobite BiceratopsFossilized skeleton of the Triassic bony fish BirgeriaFossils and restoration of the Triassic bony fish BirgeriaLife restoration of the Triassic bony fish BirgeriaAmber-entombed specimen of the Early-Late Cretaceous ant BaikurisA living Brachaelurus, or blind sharkAmber-entombed specimen of the Late Cretaceous ant BrownimeciaRestoration of the Late Cretaceous tyrannosaur BistahieversorIllustration of fossils of the Cambrian trilobite BathydiscusFossil of the Middle Devonian trilobite BellacartwrightiaIllustration of fossils of the Cambrian trilobite BolbopariaFossil of the Ordovician echinoderm BolboporitesFossilized heads of the Silurian eurypterid ("sea scorpion") BuffalopterusLiving Busycotypus whelk sea snailsA living Balearica, or crowned craneRestoration of the Pliocene toothed whale BohaskaiaShell of a Boonea seminuda sea snailFlower of a living BraseniaA living Brotula cusk eelAmber-entombed specimen of the Early-Late Cretaceous ant BaikurisFossilized skeleton of the Late Cretaceous crocodilian BorealosuchusIllustration of a fossilized skull of the Permian primitive reptile BolosaurusIllustration and interpretive diagram of a fossilized skull of the Permian primitive reptile BolosaurusIllustration in multiple views of a fossilized partial mandible of the Permian primitive reptile BolosaurusFossilized skeleton of the Late Jurassic long-necked dinosaur BrontosaurusShell of a Bathybembix sea snailA living Botaurus lentiginosus, or American bitternFossilized bony armor of the Late Devonian placoderm fish BothriolepisRestoration of the Late Devonian placoderm fish BothriolepisShell in multiple views of a Bostrycapulus aculeatusIllustration of a living Bythaelurus catsharkFossilized skeleton of the Eocene crocodilian BoverisuchusIllustration of a shell of a Bulimulus dealbatus land snailLife restoration of the Early Cretaceous crocodilian relative BernissartiaFossils of the Middle Jurassic-Cretaceous sea star BetelgeusiaFossilized skull of the Late Triassic phytosaur BrachysuchusRestoration of the Late Cretaceous horned dinosaur BravoceratopsLife restoration of the mysterious Cambrian animal BranchiocarisRestorative model of the Eocene shrew-like mammal BatodonoidesFlowers of a living Bauhinia treeFruit and foliage of a living BeilschmiediaFossilized skeleton of the Miocene-modern bird of prey ButeogallusRestorative portrait of the Permian synapsid (mammal prescursor) BurnetiaFossilized vertebrae of the Pliocene baleen whale BalaenotusFossilized skeleton of the Eocene conger eel Bolcyrus
Fossilized shell of the Late Cretaceous ammonoid Collignoniceras
Extremely hypothetical Restoration of the mysterious Late Triassic reptile Crosbysaurus
Modern mounted skeleton of Canis lupus, the grey wolf, to scale with a fossilized skeleton of the Pleistocene wolf Canis dirus, or dire wolf
Fossilized cranium of the Pliocene-Pleistocene hyena Chasmaporthetes
Life restoration of the Pliocene-Holocene elephant relative Cuvieronius
Fossilized elements of the Carboniferous conodont CavusgnathusA living Cliona spongeIllustration in multiple views of a fossilized skull of the Pleistocene Canis armbrusteri, or Armbruster's wolfIllustration of a fossilized cranium of the Pleistocene Canis armbrusteri, or Armbruster's wolfFossil of the Devonian-Triassic arthropod trackway ichnogenus CruzianaFossil of the Devonian-Triassic arthropod trackway ichnogenus CruzianaFossilized shell of the Permian ammonoid cephalopod CyclolobusRestoration of the Late Triassic ichthyosaur CalifornosaurusDiagram depicting the Late Triassic ichthyosaur Californosaurus with an anachronistic human to scale.Fossilized shell of the Late Cretaceous ammonoid cephalopod CalycocerasA living Cerithidea horn sea snailTwo views of a fossilized shell of a Cerithium cerith sea snail50 second video of snails (most likely Natica chemnitzi and Cerithium muscarum) feeding on the sea floor in the Gulf of California, Puerto Peñasco, MexicoFossilized shell of the Early Cretaceous ammonoid cephalopod CrioceratitesFossilized shell of the Early Cretaceous ammonoid cephalopod CrioceratitesFossilized shell of the Early Cretaceous ammonoid cephalopod CrioceratitesFossilized shell of the Late Jurassic-Oligocene nautiloid cephalopod CymatocerasFossilized partial skeleton of the Middle-Late Triassic ichthyosaur CymbospondylusRestoration of the Middle-Late Triassic ichthyosaur CymbospondylusDiagram illustrating the Middle-Late Triassic ichthyosaur Cymbospondylus with an anachronistic human to scale.A living Calidris alba, or sanderlingShell of a Californiconus californicus, or California cone sea snailA living Calliostoma annulatum, or purple-ring top sea snailA modern Calliostoma tricolor, or three-coloured top shell sea snailIllustration of a living Calosoma, or caterpillar huntersFlowers of a Calyptranthes, or lidflowerA Camponotus festinatus carpenter antA living Canis latrans, or coyoteA living Carcharodon carcharias, or great white sharkA living Carya, or hickory treeA living Cathartes aura, or turkey vultureFlowers of living Ceanothus, or California lilacFoliage and fruit of a living Celtis, or hackberryA living Cepphus columba, or pigeon guillemotA living Cercocarpus, or mountain mahoganyA living Cetorhinus, or basking sharkRestoration of the Miocene-Pliocene whale CetotheriumIllustration of a living Chaenophryne dreamerClose-up portrait of a Chauliodus, or viperfishFlock of living Anser caerulescens (formerly Chen caerulescens), or snow gooseRestoration of the Pleistocene-Holocene Chendytes, or Law's diving-gooseA living Chlamys hastata, or spear scallopShell of Chlamys swifti, or Swift's scallopThree living Chlorostoma sea snailsA living Chrysocyon brachyurus, or maned wolfA living Cinnamomum, or cinnamon treeA living Citharichthys stigmaeus, or speckled sanddabShells in multiple orientations of Clathrodrillia sea snailsA living Cnemidophorus, or whip-tail lizardA living Colaptes, or flickerShell in two views of a Conasprelloides cone sea snailShell of a Conus regularis, or regular cone sea snailShell in two views of a Conus scalaris, or ladder cone sea snailA living Copris scarabA living Coragyps atratus, or American black vultureShell of a Crassispira sea snailFruit of four difference species of Crataegus, or hawthorn treeLiving Crepidula adunca, or hooked slipper sea snailsShell in multiple views of a Crepidula onyx, or onyx slipper sea snailA living Crotalus viridis, or prairie rattlesnakeBranch and fruit of a CryptocaryaA living Cryptotermes, or drywood termiteA living Culicoides biting midgeBranch with fruit of a CupaniaA living Cupressus, or cypress treeA living Cyanocitta stelleri, or Steller's jayIllustration of a living Cyclothone bristlemouthA living Cygnus columbianus, or tundra swanUnderside of a fossilized cranium of the Oligocene-Miocene bone-crushing dog CynarctoidesFossilized cranium of the Miocene bear-dog CynelosFossilized mandible of the Miocene bear-dog CynelosIllustration of a living Cyrtonyx quailRestoration of the Permian synapsid (mammal precursor) CutleriaFlower of a living CaesalpiniaA living Calcarius lapponicus, or Lapland longspurA living Calcarius ornatus, or chestnut-collared longspurA living larva of a Caliroa sawflyIllustration of a living Callomyia flat-footed flyA living Camponotus, or carpenter antA living Carabus ground beetleA living Cardiophorus click beetleA living member of the vine genus CardiospermumA living Haemorhous cassinii (formerly Carpodacuscassinii), or Cassin's finchFoliage and fruit of a living Celastrus, or staff vineA living Ceratina, or small carpenter beesRestoration of the Paleocene-Eocene crocodilian CeratosuchusFlowers of a living Cercis or redbud treeA living Chalybion, or blue mud dauberA stand of living Chamaedorea palmsA living Cheilosia hoverflyA living Chilocorus ladybugA living Chironomus midgeA living Chondestes grammacus, or lark sparrowA living Chrysogaster hoverflyFossilized tooth of the Late Cretaceous-Paleocene multituberculate mammal CimexomysA living Cleonus weevilA living Clubiona, or leafcurling sac spiderA living Coccinella ladybugA living Colaptes auratus, or northern flickerA living member of ColubrinaIllustration of a living Coniatus weevilA living Conotrachelus weevilA living Corizus scentless plant bugA living Cryptocheilus spider waspA living Cryptophagus silken fungus beetleA living Cryptorhynchus weevilA living Culex mosquitoA living Curculio, or acorn weevilA living Cylindrotoma crane flyA living Cynomys, or prairie dogFossil of the Early-Middle Ordovician trilobite ColpocorypheFossilized tooth of the Miocene-Pliocene shark Cosmopolitodus hastalis, or broad-toothed makoFossilized shells of the Miocene-Pleistocene scallop ChesapectenA living CrocodylusA living Calidris canutus, or red knotA living Calidris pusilla, or semipalmated sandpiperShell of a Calliostoma euglyptum, or sculptured top shellShell of a Calliostoma jujubinumShell of a Calliostoma roseolumIllustration in multiple views of the shell of a Calliostoma tampaenseIllustration in multiple views of the shell of a Calliostoma yucatecanumFossilized skeleton of the Pliocene-Holocene camel CamelopsRestoration of the Pliocene-Holocene camel CamelopsShell in multiple views of a Cancellaria reticulata, or common nutmegIllustration in multiple views of the shell of a Cancilla mitre shell sea snailA living Cardinalis cardinalis, or northern cardinalA living Caretta caretta, or loggerhead sea turtleLiving Carex, or true sedgeA living Carphophis amoenus, or worm snakeShell of a Carychium land snailA living Ardea alba, or great egretShell in multiple views of a Cassis madagascariensis, or queen helmet sea snailA living Castor canadensis, or North American beaverA living Centropomus, or snookLiving Cerastoderma cocklesShells of Cerithideopsis pliculosa, or the plicate horn shell sea snailShell of a Cerithium muscarum cerith sea snailA living Ceryle rudis, or pied kingfisherA living Chaetopleura apiculata chitonA living Chamelea venus clamA living Chelonia mydas, or green sea turtleShells of the Pliocene scallop Chesapecten jeffersoniusShell in multiple views of a Chicoreus brevifrons, or West Indian murexShell of a Chicoreus florifer, or flowery lace murexA living Chilomycterus, or burrfishExteriors (above) and interiors of shells of Chione cancellata venus clamsShells in differing orientations of Chrysallida pyram sea snailsFossilized skeleton of the Pliocene-Pleistocene Ciconia maltha, also known as the asphalt stork or La Brea storkA living Circus cyaneus, or hen harrierFossilized Cladocora stony coralA living Clangula hyemalis, or long-tailed duckShell of a Clavatula sea snailA living Aspidoscelis sexlineata (formerly Cnemidophorus sexlineatus), or six-lined racerunnerA living Coccyzus americanus, or yellow-billed cuckooLiving Colpophyllia natans, or boulder brain coralShell in multiple views of Columbella mercatoria dove sea snailsFossil of the Miocene-Pleistocene barnacle ConcavusIllustration of a living Conepatus leuconotus, or American hog-nosed skunkShell in multiple views of a Conus anabathrum cone sea snailShell in multiple views of a Conus daucus cone sea snailShell in multiple views of a Conasprella delessertii (formerly Conus delessertii), or Sozon's cone sea snailShell in multiple views of a Conasprella jaspidea (formerly Conus jaspideus), or jasper cone sea snailShell in multiple views of a Conus patricius, or patrician cone sea snailShell in multiple views of a Conus sennottorum, or Sennett's cone sea snailShell in multiple views of a Conus spurius, or alphabet cone sea snailShell of a Coralliophila murex sea snailA living Corvus ossifragus, or fish crowA living Coturnicops noveboracensis, or yellow railShell of a Crepidula maculosa slipper sea snailShell of a Crepidula plana eastern white slippersnailA living Crotalus adamanteus, or eastern diamondback rattlesnakeShell in multiple views of a Crucibulum spinosum, or spiny cup-and-saucer snailShell in multiple views of a Crucibulum striatum, or striate cup-and-saucer sea snailA living Cryptotis parva, or North American least shrewA living Cyanocitta cristata, or blue jayA living Cygnus buccinator, or trumpeter swanShell of a Cymatosyrinx sea snailLiving Cymodocea sea grassA modern Cynoscion drumA living Cyphoma gibbosum, or flamingo tongue snailShell in multiple views of a Cypraecassis helmet sea snailShell in multiple views of a Cyrtopleura costata, or angel wing clamFossilized fronds of the Carboniferous seed fern CallipteridiumFossil of the Silurian trilobite Calymene celebraA living Chiloscyllium longtail carpet sharkA living ChitonA living Carcharhinus obscurus, or dusky sharkA living Carcharias taurus, or sand tiger sharkA living Carcharodon sharkA living Chelydra serpentina, or common snapping turtleElectron micrograph of a Coccolithus algaFoliage of a living Canarium treeShell in multiple views of a Conus ebraeus, or black-and-white cone sea snailsA living Conus geographus, or the geography cone sea snailFossil of the Jurassic-Cretaceous cycad relative CycadeoideaFossilized fruit of a Craigia plantFossils in enrolled posture of the Silurian trilobite Calymene niagarensisFossil of the Silurian eurypterid ("sea scorpion") CarcinosomaRestoration of the Carboniferous Chimaera relative CaseodusChancelloriaRestoration (foreground) of the Permian-Jurassic lobe-finned fish CoelacanthusFossilized skeleton of the Permian-Jurassic lobe-finned fish CoelacanthusFossilized skeleton of the Carboniferous-Permian reptile relative CricotusIllustration of a fossilized skull and ventral scutes of the Carboniferous-Permian reptile relative Cricotus. Edward Drinker Cope (1884).Fossilized stem segments of the Silurian crinoid ("sea lily") CrotalocrinitesFossilized calyx and partial stem of the Silurian-Permian crinoid ("sea lily") CyathocrinitesRestoration of the Pleistocene Cervalces scotti, or stag-mooseLife restoration of the Miocene-Pleistocene horned gopher Ceratogaulus. Robert Bruce Horsfall (1913).Fossilized skull of the Miocene pronghorn CosoryxA living Cynomys ludovicianus, or black-tailed prairie dogRestoration of a dead Late Cretaceous duck-billed dinosaur, Claosaurus, floating in the Western Interior Sea of Kansas, while a Cretoxyrhina and two Squalicorax prepare to scavenge itFossilized calyx of the Carboniferous crinoid ("sea lily") CydrocrinusA living Centropristis, or sea bassA living Citharichthys large-tooth flounderA living CongerElectron micrograph of the shell of a Cyclammina foraminiferanFossilized vertebrae in multiple views of the Cretaceous plesiosaur CimoliasaurusIllustration of a fossilized tibia of the Late Cretaceous theropod dinosaur Coelosaurus antiquusA living Callinectes sapidus, or Chesapeake blue crabA living Calonectris shearwaterA living Cancer irroratus, or Atlantic rock crabA living Myodes gapperi, or southern red-backed voleShell in multiple views of a Crepidula fornicata, or common slipper shell sea snailShells in differing orientations of Colus whelk sea snailsIllustration of a living Cymindis ground beetleLiving Chelonibia acorn barnaclesFossilized skeleton of the Carboniferous coelacanth CaridosuctorLife restoration of the Late Cretaceous horned dinosaur CentrosaurusRestoration of the Late Cretaceous horned dinosaur CerasinopsRestoration of the Late Cretaceous horned dinosaur ChasmosaurusFossilized hand and foot bones of the Late Cretaceous oviraptorosaur ChirostenotesFossilized skeleton of the Late Cretaceous duck-billed dinosaur CorythosaurusFlowers and foliage of living Canavalia, or jack-beansLife restoration of the Paleocene primate relative CarpolestesFossilized skeleton of the Eocene turtle ChisternonFlower of a living ClematisIllustration of fossilized vertebrae of the Late Cretaceous-Eocene snake Coniophis. Othniel Charles Marsh (1892).A living Cornus, or dogwoodFossilized leaf from a Credneria treeA living Culiseta mosquitoLiving Cedrela treesFlowers of a living Cladrastis, or yellowwoodA taxidermied Conuropsis carolinensis, or Carolina parakeetFossil of the Cambrian arthropod CanadaspisRestoration of the Cambrian arthropod Canadaspis (left)Fossil of the Triassic bony fish ColobodusFossilized skeleton of the Triassic bony fish ColobodusFossilized shell of the Early Jurassic ammonoid cephalopod CoronicerasFossilized carapace of the Paleocene-Miocene crab CalappiliaShell of a Cardites marine bivalveRestoration of the Carboniferous-Permian amphibian ChenoprosopusFossilized skull in multiple views of the Carboniferous-Permian amphibian ChenoprosopusFossilized skeleton of the Middle Triassic-Paleocene bony fish CoelodusRestoration of the Late Triassic-Early Jurassic theropod dinosaur Coelophysis with an anachronistic human to scaleFossilized skeleton of the Late Triassic-Early Jurassic theropod dinosaur CoelophysisA living Chaetodipus pocket mouseA living Cophosaurus texanus, or greater earless lizardIllustration of a fossil and restoration of the Early Ordovician nautiloid cephalopod CassinocerasFossils (1 and 2) of the Silurian eurypterid ("sea scorpion") ClarkeipterusFossils (1-8) of the Silurian eurypterid ("sea scorpion") ClarkeipterusA living Craniella spongeFossils and restoration of the Silurian eurypterid ("sea scorpion") CtenopterusFossils (1-7) of the Silurian eurypterid ("sea scorpion") CtenopterusA living Calidris melanotos, or pectoral sandpiperA living Calonectris borealis, or Cory's shearwaterA living Carcharhinus falciformis, or silky sharkIllustration of a living Centropristis striata, or black sea bassIllustration of a living Ceratoscopelus lanternfishA living Cerorhinca monocerata, or rhinoceros aukletA living Chilomycterus schoepfi, or striped burrfishLiving Ciconia storksLiving Clathrus stinkhorn fungiA Coelopleurus sea urchinA living Conger oceanicus, or American congerA living Coscinodiscus diatomShell of a Cotonopsis lafresnayi, or well-ribbed dove sea snailShells of Cumingia marine clamsIllustration of a living Cynoscion nebulosus, or spotted seatroutKnown material diagram illustrating a reconstructed skull and body of the Late Triassic distant crocodilian relative CarnufexLiving Ceratophyllum, also known as coontails or hornwortsTrunk and foliage of a living Cercidiphyllum, or katsura treeFossilized skeleton of the Permian amphibian CacopsLife restoration of the Permian amphibian CacopsFossilized skeletons of the Permian reptile CaptorhinusRestoration of the Permian reptile CaptorhinusRestoration of the Permian amphibian CardiocephalusIllustration of a fossilized cranium of the Permian primitive reptile ColobomycterFossilized skeleton of the Permian synapsid (mammal precursor) CotylorhynchusRestoration of the Permian synapsid (mammal precursor) CotylorhynchusFossilized skeleton of the Permian synapsid (mammal precursor) CotylorhynchusDiagram illustrating the size of the Permian synapsid (mammal precursor) Cotylorhynchus, with an anachronistic human to scaleFossilized skull of the Carboniferous-Permian reptile relative CricotusFossil of the Carboniferous-Permian trilobit CummingellaFoliage and cones of a living Calocedrus, or incense cedarA living Choerodon wrasseShell of a Comitas sea snailA taxidermied Cryptotis , or small-eared shrewA living Crocuta crocuta, or spotted hyenaRestoration of the Cambrian echinoderm CamptostromaA living Charina boaFossilized skeleton of the Permian-Early Cretaceous bony fish CaturusShells of Candona ostracodsA living Catagonus wagneri, or Chacoan peccaryFruit and foliage of a living Cissus vineFruit and foliage of a living Combretum, or bushwillowA living Corvus brachyrhynchos, or American crowA living Crotalus atrox, or western diamondback rattlesnakeA living Crotaphytus collaris, or common collared lizardReconstruction of a fossilized skeleton of the Permian amphibian Cacops. Samuel Wendell Williston.Fossilized skeleton of the Permian reptile CaptorhinusFossilized skeleton of the Permian synapsid (mammal precursor) CaseaDiagram illustrating the Permian synapsid (mammal precursor) Casea with an anachronistic human to scaleLife restoration of the Permian synapsid (mammal precursor) CaseaLife restoration of the Permian synapsid (mammal precursor) CotylorhynchusShell of a Cancellaria nutmeg sea snailRestoration of the Late Cretaceous turtle ChupacabrachelysLife restoration of the Late Cretaceous pterosaur Cimoliopterus (left) stealing fish from another pterosaurFossilized skulls of the Late Triassic–Early Jurassic tuatara relative ClevosaurusFossils of the Cretaceous sea urchin ConulusFossil of the Cambrian sponge ChoiaRestoration of the Cambrian sponge ChoiaA living Calamospiza melanocorys, or lark buntingA living Caracara plancus, or southern crested caracaraA living Carduelis finchLife restoration of the Paleocene primate relative Carpolestes simpsoniA living Centrocercus urophasianus, or greater sage-grouseA living Cercopis froghopperA living Charadrius montanus, or mountain ploverA living Chordeiles minor, or common nighthawkA living Coccothraustes vespertinus, or evening grosbeakFruit and foliage of a living Cocculus, or moonseedFossilized skull of the Eocene crocodilian "Crocodylus" affinisFossilized illium in multiple views of the Early Cretaceous Iguanodon relative CedrorestesRestoration of the Late Jurassic primmitive tyrannosaur CoelurusFossilized skull of the Eocene crocodilian Crocodylus acerShell and operculum of a living Campeloma freshwater snailFossilized skeleton of the Late Cretaceous-Eocene choristodere reptile ChampsosaurusIllustration in multiple views of a fossilized coracoid of the Late Cretaceous bird CimolopteryxLife restoration (figure 12) of the Early Triassic plesiosaur relative CorosaurusFossil of the Cambrian trilobite ConocorypheRestoration of the Carboniferous four-limbed animal precursor CrassigyrinusFossil of the Triassic crocodilian relative footprint ichnogenus ChirotheriumA living Charadrius vociferus, or killdeerA living Chordeiles minor, or common nighthawkA living Cistothorus stellaris, or sedge wrenFossilized skeleton of the Eocene bony fish CyclopomaFossilized tooth of the Carboniferous Chimaera relative CampodusRestoration of the Carboniferous Chimaera relative CampodusRestoration of the Early Devonian jawless fish CephalaspisFossilized skeleton of the Early Devonian jawless fish Cephalaspis
Restoration of two species of the Silurian trilobite DeiphonFossil and mold of the Late Ordovician-Silurian trilobite DiacalymeneFossil of the Cambrian trilobite DaguinaspisFossils of the Cambrian-modern arthropod trackway ichnogenus DiplichnitesFossilized shell of a Discohelix sea snailLife restoration of the Miocene bear-dog DaphoenodonFossilized skeleton of the Eocene-Miocene bear-dog DaphoenusA school of living Decapterus, or mackerel scadsA living Dendragapus obscurus, or dusky grouseA living Dendraster excentricus, or sea cakeA living Dendryphantes jumping spiderA living Dermochelys, or leatherback sea turtleA living Deroceras land slugFacial features of various Diomedea, or great albatross, species.A living member of Diospyros, the tree genus including ebonies and persimmonsA living Dipodomys merriami, or Merriam's kangaroo ratIllustration of a cluster of the Jurassic-modern brachiopod DisciniscaShell of a Distorsio sea snailFossilized horns, jaws, and limb bones of the Miocene deer relative DromomeryxFossilized jaws and teeth of the Eocene brontothere mammal DuchesneodusRestoration of the Miocene-Pliocene manatee relative DusisirenA living Daphnia water fleaRestoration of the Eocene-Miocene bear dog DaphoenusLiving Dennstaedtia, or hayscented fernsPreserved Dermatobia hominis, or human botfly specimenA living Dermestes skin beetleA living Diabrotica, or corn rootwormRestoration of two of the Eocene even-toed ungulate Diacodexis being hunted by a primitive whaleRestoration of two of the Eocene even-toed ungulate DiacodexisIllustration of a living Dicerca jewel beetleA living Dicranomyia crane flyA living Dicranota hairy-eyed craneflyFossilized skeleton of the Eocene-Miocene false saber-toothed cat DinictisLife restoration of the Eocene-Miocene false saber-toothed cat Dinictis. Robert Bruce Horsfall (1913).Fossilized skeleton of the Miocene-Pliocene horse DinohippusA living Diploptera, or beetle cockroachA living Dipodomys ordii, or Ord's kangaroo ratFoliage and flowers of a living Dodonaea, or hop-bushPreserved Dolichoderus antA living Doxocopa brush-footed butterflyRestoration of the Late Cretaceous primitive tyrannosaur DryptosaurusShell in multiple views of a Daedalochila uvulifera, or peninsula liptooth land snailFossilized cranium seen from above and below of the Pleistocene Dasypus bellus, or beautiful armadilloLiving Dendrogyra, or pillar coralShell of a Dermomurex elizabethae murex sea snailShell of a Dicathais white rock shell sea snailLiving Dichocoenia stokesi, or elliptical star coralShells of Diodora cayenensis, or Cayenne keyhole limpetLiving Diploria labyrinthiformis, or grooved brain coralShells of Donax variabilis, or coquinaA living Vanellus chilensis, or southern lapwingClose-up portrait of a living Drymarchon corais, or indigo snakeA living Dryocopus woodpeckerFossil of the Late Ordovician-Middle Devonian trilobite DipleuraRestoration of the Late Cretaceous Alligator relative DeinosuchusFossilized mandible in multiple views of the Pleistocene Dasypus bellus, or beautiful armadilloA living Didelphis marsupialis, or common opossumElectron micrograph of a Discoaster algaFossilized axial skeleton of the Carboniferous-Permian amphibian DiplocaulusFossils of the Carboniferous crinoid ("sea lily") DizygocrinusFossil of the Silurian-Late Devonian eurypterid ("sea scorpion") DrepanopterusFossils of the Cambrian-modern arthropod trackway ichnogenus DiplichnitesShell in multiple views of a Dorsanum Nassa mud sea snailLife restoration of the Early Cretaceous dromaeosaur ("raptor") DeinonychusUnderside of the reconstructed cranium of the Miocene baleen whale DiorocetusFossil shell of the Cretaceous-modern marine venus clam DosiniaFossilized leaves of the Carboniferous-Permian gymnosperm DorycordaitesRestoration of the Eocene whale DorudonA living Donacia leaf beetleRestoration of the Carboniferous Chimaera relative DelphyodontosIllustration of the fossilized pygidium (tail segment) of the Cambrian trilobite DikelocephalusFossilized skull of the Late Cretaceous tyrannosaur DaspletosaurusFossilized skeleton of the Late Cretaceous Alligator relative DeinosuchusFossilized skeleton of the Late Cretaceous marsupial relative DidelphodonRestoration of the Late Jurassic long-necked dinosaur DiplodocusFossilized pelvis and tail of the Late Cretaceous armored dinosaur DyoplosaurusFoliage of a living Dalbergia retusa treeFossilized samara of the Eocene-modern Dipteronia treeIllustration of a living Dicrostonyx torquatus, or Arctic lemmingA living Dipodomys, or kangaroo ratRestoration of the Late Cretaceous marsupial relative DidelphodonFossilized skeleton of the Paleocene-Miocene crocodilian DiplocynodonRestoration of the Late Cretaceous primitive tyrannosaur DryptosaurusIllustration of a fossilized tooth of the dubious Late Cretaceous reptile genus DiplotomodonFossilized skeleton of the Permian reptile relative DiadectesLife restoration of the Permian reptile relative DiadectesFossilized skull of the Permian reptile relative DiadectesFossilized skeleton of the Permian synapsid (mammal precursor) DimetrodonFossilized skull of the Permian synapsid (mammal precursor) DimetrodonLife restoration of the Permian synapsid (mammal precursor) DimetrodonFossilized skull of the Late Triassic theropod dinosaur DaemonosaurusRestoration of the Late Cretaceous tyrannosaur Daspletosaurus feeding on a horned dinosaurRestoration of the Late Triassic reptile DoswelliaRestoration of the Late Triassic reptile DrepanosaurusFossil of the Carboniferous-Late Cretaceous petrified conifer wood morphogenus DadoxylonFossil of the Silurian eurypterid ("sea scorpion") DolichopterusA living Dasyatis americana, or southern stingrayShell of a Dermomurex murex sea snailA living Dictyochales algaShell of a Dinocardium robustum, or Atlantic giant cockleShell exteriors and interiors of Donax fossor marine clamsFossilized skeleton of the Triassic coelacanth DiplurusInterpretive diagrams and fossils of a skull of the Permian primitive reptile DelorhynchusReconstructions of the youngest and most mature skulls of the Permian primitive reptile DelorhynchusDicranurusFossil of the Early Devonian trilobite DicranurusFossilized skeleton of the Eocene pseudo-toothed bird DasornisA preserved Diacheila ground beetleRestoration of the Middle Devonian lungfish DipterusLife restoration of the Permian amphibian DiploceraspisLife restoration of a swimming group of the Permian amphibian DiploceraspisA living Dendraster sand dollarRestoration of the Late Cretaceous dromaeosaurid ("raptor") Dakotaraptor preying upon an ostrich dinosaurRestoration of the Late Cretaceous primitive mosasaur DallasaurusFossilized skeleton of the Late Triassic tuatara relative DiphydontosaurusLiving Diploastrea heliopora coralFossilized skeleton of the Late Cretaceous plesiosaur DolichorhynchopsShell of a Dreissena freshwater musselFossilized shells of the Early Cretaceous ammonoid cephalopod DufrenoyiaRestoration of the Permian amphibian DasycepsFossilized skeleton of the Permian reptile relative DiadectesFossilized skull of the Permian reptile relative DiadectesFossilized partial skeleton of the Carboniferous amphibian DissorophusFossilized skull of the Carboniferous amphibian DissorophusFossilized skull of the Carboniferous amphibian DissorophusRestoration of the Late Cretaceous horned dinosaur DiabloceratopsA living DendropanaxIllustration of a living Dicrostonyx, or collared lemmingFossilized skeleton of the Early Cretaceous-Eocene bony fish Diplomystus preserved in the act of swallowing another fishA living Distylium, or winter-hazelA living Dolichopus flyFlower of a living DrimysRestoration of the Late Cretaceous tyrannosaur DaspletosaurusIllustration of a fossil of the feeding burrow ichnogenus Diplocraterion. Rudolph Richter (1926)Restoration of the Late Cretaceous "raptor" DromaeosaurusRestoration of the Silurian-Early Devonian primitive vascular plant DistichophytumFossilized skeleton of the Eocene brontothere mammal DiplacodonA living Discus catskillensis land snail, or angular discA living Dryocopus pileatus, or pileated woodpecker
Fossilized shells and restored appearances of the Middle-Late Ordovician nautiloid cephalopod Endoceras
Fossilized shell of the Middle-Late Ordovician nautiloid cephalopod Endoceras
Fossil of the Silurian-Early Devonian eurypterid ("sea scorpion") Erettopterus
Restoration of the Silurian-Early Devonian eurypterid ("sea scorpion") Erettopterus
Illustration of fossils of various organs and stages of development of the Silurian-Early Devonian eurypterid ("sea scorpion") Erettopterus
Fossilized calyx of the Silurian-Middle Devonian crinoid ("sea lily") Eucalyptocrinites
Fossilized shell of the Silurian-Permian sea snail Euomphalus
Restoration of Silurian eurypterid ("sea scorpion") Eurypterus
Anatomy of the Silurian eurypterid ("sea scorpion") Eurypterus
Fossil of the Silurian eurypterid ("sea scorpion") Eurypterus
Fossil of the Middle-Late Devonian trilobite Eldredgeops
Fossilized holdfast of the Silurian-Middle Devonian crinoid ("sea lily") Eucalyptocrinites
Restoration of the Late Cretaceous armored dinosaur Edmontonia
Skeletal reconstruction and restored soft tissue of the Late Cretaceous duck-billed dinosaur Edmontosaurus regalis with an anachronistic human to scale
Restoration of the Early Cretaceous-Eocene bony fish Enchodus, or the "saber-toothed herring"
Restoration of the Early Jurassic amphibian Eocaecilia
Restoration of the Middle Triassic amphibian Eocyclotosaurus
Fossilized shell of the ammonoid cephalopod Eucalycoceras
Restoration of the Pliocene-Holocene horse Equus scotti, or Scott's horse
Fossil of the Middle Ordovician-Early Devonian trilobite EncrinurusCast fossils of the Devonian-modern sponge boring ichnogenus EntobiaFossilized skull of the sea turtle EuclastesFossilized shell of the Late Cretaceous ammonoid cephalopod EupachydiscusFossilized shell of the Late Cretaceous ammonoid cephalopod ExitelocerasIllustration of a living Echinorhinus sharkA living Eleodes osculans, or wooly darkling beetleA living Elgaria multicarinata, or southern alligator lizardRestoration of two of the Eocene-Oligocene anthracothere mammal Elomeryx being menaced by fellow-anthracothere AnthracotheriumRestoration of the Oligocene-Miocene Enaliarctos and the toothed whale Macrodelphinus (background)Interior of the shell of an Ensis, or razor clamFossilized skeleton of the Eocene-Pliocene frog EopelobatesUnderside of the fossilized cranium of the Eocene horse EpihippusA living Epinephelus, a member of the family including sea basses and groupersShell in multiple views of an Epiphragmophora land snailRestoration of the Pleistocene-Holocene Equus conversidens, or Mexican horseRestoration of the Pleistocene bovid Euceratherium, or the shrub ox. Robert Bruce Horsfall (1913).Living Eumetopias jubatus, or Steller's sea lionsA living Neverita lewisii, or Lewis's moon sea snailA living Eutamias chipmunkRestoration of the Late Devonian-Carboniferous Chimaera relative EdestusLife restoration of the Carboniferous-Permian amphibian EryopsFossilized shell of the Eocene turtle EchmatemysA living Ectobius wood cockroachFossilized skull of the Paleocene-Eocene mammal Ectocion
Restoration of the Paleocene mammal EctoconusFossilized skeleton of the Paleocene mammal EctoconusIllustration of a living Eleodes, or Pinacate beetleA living Empis daggerflyA living Enochrus water scavenger beetleRestoration of a pair of the Eocene uintathere mammal Eobasileus. Charles R. Knight (1890s).Fossilized skeleton of the Eocene horse EohippusRestoration of the Eocene horse Eohippus. Heinrich Harder (1920).Restoration of the Eocene brontothere mammal EotitanopsLiving member of the shrub genus Ephedra, which includes the joint-pines and Mormon teaA living Epicauta blister beetleGalls on a leaf caused by Eriophyes mitesA living Ethmia mothFoliage and flowers of a living Eucommia treeBranches and fruits of a living EugeniaFossil of the Eocene ant EulithomyrmexA living Euphorbia, or spurgeA living Tamias minimus (formerly Eutamias minimus), or least chipmunkRestoration of the Late Triassic crocodile relative ErpetosuchusShell of an Echinocardium, or heart urchinA living Echinometra lucunter, or rock boring urchinA living Egretta thula, or snowy egretShell of an Engina sea snailIllustration in multiple views of the shell of a Epitonium novangliae, or New England wentletrapA living Equetus punctatus, or spotted drumFossilized skeleton of the Pliocene-Pleistocene ground sloth EremotheriumA living Erethizon dorsatum, or North American porcupineA living Eretmochelys imbricata, or hawksbill sea turtleA living Eubalaena, or Right whaleA living Eucidaris tribuloides, or slate pencil urchinA living Eudocimus albus, or American white ibisA living Euglandina rosea, also known as the rosy wolfsnail or the cannibal land snailA living Plestiodon fasciatus, or American five-lined skinkA living Eumops glaucinus, or Wagner's bonneted batA living Euphagus cyanocephalus, or Brewer's blackbirdShell of a Euvola raveneli, or Ravenel's scallopFossil of the Late Devonian-Carboniferous Chimaera relative EdestusFossilized skeleton of the Carboniferous-Permian bony fish ElonichthysFossilized skeleton of the Carboniferous-Permian bony fish ElonichthysIllustration of fossil of the Carboniferous millipede EuphoberiaFossilized calyx and partial stem of the Carboniferous crinoid ("sea lily") EretmocrinusFossils (figures 2-10) of the Silurian-Devonian eurypterid ("sea scorpion") ErieopterusFossilized skeleton and interpretive diagram of the Carboniferous synapsid (mammal precursor) EocaseaRestoration of the Carboniferous synapsid (mammal precursor) EocaseaFossilized skull and interpretive diagram of the Carboniferous synapsid (mammal precursor) EocaseaFossilized skeleton of the Carboniferous amphibian EoscopusFossilized partial skeleton of the Late Cretaceous mosasaur EctenosaurusRestoration of the Late Cretaceous plesiosaur Elasmosaurus with an anachronistic human to scaleA living Eumeces skinkIllustration of a shell in multiple views of the Late Jurassic-Miocene nautiloid cephalopod EutrephocerasFossils of the Devonian-modern borehold ichnogenus Entobia in a quahog shellFossilized cranium in multiple views of the Paleocene-Eocene gavial relative EosuchusLife restoration of the Miocene whale Eurhinodelphis (above)Fossils of the large theropod dinosaur footprint ichnogenus EubrontesFossil of the Early-Middle Ordovician cystoid echinoderm EchinosphaeritesFossil of the crustacean ErymaFossilized shell of the Jurassic-Cretaceous foam oyster ExogyraIllustration of a living Esox lucius, or northern pikeInterior of the shell of an Ensis leei, or Atlantic jackknife clamLife restoration of the Late Cretaceous plesiosaur EdgarosaurusRestoration of the Late Cretaceous duck-billed dinosaur Edmontosaurus annectensRestoration of the Late Cretaceous horned dinosaur EiniosaurusRestoration of the Late Cretaceous armored dinosaur EuoplocephalusRestoration of the Eocene-Oligocene anthracothere mammal ElomeryxFossilized fruit of the Eocene Eucommia montana plantFoliage and fruit of a modern EuonymusA living Emys blandingii, or Blanding's turtleRestoration of the Miocene elephant relative EubelodonIllustration with inset cross-section diagrams of the Cambrian sponge EthmophyllumFossils of the Middle Triassic crinoid ("sea lily") EncrinusDiagram of the anatomy of the Middle Triassic crinoid ("sea lily") EncrinusRestoration of the Late Cretaceous plesiosaur ElasmosaurusFossilized shell in multiple views of the Late Cretaceous-Paleocene sea urchin EchinocorysIllustration of a fossilized shell of the Eocene-Pliocene murex sea snail EcphoraFossilized skull of the Eocene sea turtle EosphargisFossilized skeleton of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusDiagram illustrating the size of the Carboniferous-Permian synapsid (mammal precursor) Edaphosaurussize, compared to a human.Illustration in multiple views of a fossilized skull of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusRestoration of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusFossilized skeleton of the Carboniferous-Permian amphibian EryopsRestoration of the Late Triassic distant crocodilian relative EffigiaFossilized mandible in multiple views of the Late Cretaceous mammal EodelphisDiagram illustrating the size of average (orange) and record-setting (green) specimens of the Silurian eurypterid ("sea scorpion") Eurypterus, with an anachronistic human to scaleFossil of the Silurian eurypterid ("sea scorpion") EurypterusA living Eudocimus ibisLife restoration of the Permian lobe-finned fish EctosteorhachisFossilized skeleton of the Permian lobe-finned fish EctosteorhachisRestoration of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusReplica fossilized skull of the Carboniferous-Permian amphibian EryopsRestoration of the Permian synapsid (mammal precursor) EdaphosaurusFossils at different stages of development of the Cambrian trilobite ElrathiaShell of a Eucrassatella speciosa, or Gibbs' clamFossilized mandible of the Eocene-Oligocene false saber-toothed cat EusmilusA living Eremophila alpestris, or horned larkA living Eleutherodactylus, or rain frogLiving Ellisella coral, or sea whipsFossilized skeleton of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusRestoration of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusRestoration of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusFossilized skeleton of the Carboniferous-Permian synapsid (mammal precursor) EdaphosaurusRestoration of the Permian amphibian EdopsFossilized skull in multiple views of the Permian reptile EothyrisLife restoration of the Permian reptile EothyrisShell of an Epitonium sea snail, or wentletrapFossils of the Cambrian-Middle Ordovician echinoderm relative EldoniaFossil of the Cambrian arthropod EmeraldellaIllustration of a reconstructed skull and restorative portrait of the Late Cretaceous primitive duck-billed dinosaur EolambiaFossil of the Eocene bee EuglossopteryxFossil of the Cambrian trilobite EllipsocephalusRestoration of the Cambrian-Early Ordovician trilobite EntomaspisRestoration of the Cambrian echinoderm relative EocystitesDiagram illustrating the size of the Late Jurassic ceratosaur Elaphrosaurus with an anachronistic human to scaleFruit and foliage of a living ElaeodendronIllustration of a living Esox, the genus including pikes and pickerelsIllustration of a fossilized shell of the Miocene murex sea snail Ecphora gardneraeRestoration of two of the Miocene baleen whale Eobalaenoptera pursued by the giant shark Carcharocles megalodonA living Esox americanus, or American pickerel
Illustration of a fossil of the Cambrian trilobite FallotaspisModern shell of a Fissurella keyhole limpetA living Falco peregrinus, or peregrine falconFossilized shell of the Oligocen-modern scallop FlabellipectenFlower of a Forestiera, or swampprivetsA living Fragilaria diatomA living Fratercula cirrhata, or tufted puffinA living Fulica americana, or American cootA living Falcipennis grouseFossilized flower of the Eocene-Oligocene rose relative FlorissantiaA living Formica, or wood antA living Fulgora planthopperA living Falco columbarius, or merlinA living Farancia abacura, or mud snakeA living Fasciolaria tulipa, or true tulip sea snailA living Felis, or catFruit and foliage of a living Ficus carica, or Common figA living Egretta caerulea, or little blue heronShell of a Fragum cockleShell in multiple views of a Fulguropsis whelkA living FundulusIllustrations of the flowers and foliage of a living Fraxinus, or ash tree, with insets further detailing its anatomyFossil of the Middle Ordovician-Late Triassic bryozoan ("moss animal") FenestellaCollection of fossils of Silurian-Permian fusulinid foraminiferansElectron micrograph of a fossil of a Silurian-Permian fusulinid foraminiferanFossilized calyx of the Devonian-Carboniferous crinoid ("sea lily") ForbesiocrinusLiving Fistulobalanus barnaclesRestoration of the Permian Chimaera relative FadeniaFossil of the Middle Ordovician-Silurian trilobite FlexicalymeneLife restorations of a female (top) and male (bottom) of the Carboniferous Chimaera relative FalcatusA living Fokienia cypress treeShell of a Fasciolaria, or tulip sea snailFossilized shell of the Late Cretaceous ammonoid cephalopod Fagesia superstesA living Falco mexicanus, or prairie falconIllustrations of fossilized shells of the Cambrian marine bivalve FordillaA living Fratercula arctica, or Atlantic puffinRestoration of the Permian amphibian Fayella preying upon a VaranodonFossilized skull in multiple views of the Permian primitive reptile FeeserpetonFossil in an enrolled posture of the Late Ordovician trilobite FrencrinuroidesA living Fothergilla, or witch alderA living Fusconaia freshwater musselLiving Favia stony coralLiving Favia coralFossilized skeleton of the Early Cretaceous therizinossaur FalcariusA living Falco rusticolus, or gyrfalconFossilized skeleton of the Eocene bird FluvioviridavisKnown material diagram of the Late Jurassic ceratosaur Fosterovenator
Restoration of a herd of the Pliocene-Holocene ground sloth Glossotherium
Fossilized skeleton of the Pleistocene armadillo relative Glyptotherium
Fossil of the bore-hole ichnogenus Gastrochaenolites (G)Fossil of the Silurian trilobite GlyptambonFossil of the Carboniferous ammonoid cephalopod Goniatites crenistriaRestoration of the Cambrian echinoderm GogiaFossil of the theropod dinosaur footprint ichnogenus GrallatorFossil negative with skin impressions of the theropod dinosaur footprint ichnogenus GrallatorFossil of the theropod dinosaur footprint ichnogenus GrallatorA living Galeocerdo cuvier, or tiger sharkA school of living Gasterosteus aculeatus, or three-spined sticklebackLiving adult and young Gavia stellata, or red-throated loonA living Geococcyx californianus, or greater roadrunnerA living Gerrhonotus, or alligator lizardA living Glaucidium gnoma, or mountain pygmy owlLiving Globularia, or globe daisiesRestoration of the Miocene walrus GomphotariaFossilized skeleton of the Miocene-Pleistocene elephant relative GomphotheriumA living Gopherus, or desert tortoiseA living Gymnogyps californianus, or California condorA living Gaurotes longhorn beetleA living Geomys bursarius, or Plains pocket gopherIllustration of a living Glossina, or tsetse flyFossilized foliage of the cypress relative GlyptostrobusA living Gorytes sand waspFossil of the Eocene lace bug GyaclavatorA living Gallinago gallinago, or common snipeA living Gambusia affinis, or mosquitofishA living Gastrophryne carolinensis, or the eastern narrow-mouthed toadFossilized skull of the Miocene crocodile relative GavialosuchusA living Geochelone tortoiseA living Geranoaetus bird of preyShell of a Gibberula sea snailFossilized shells of the Oligocene-Pliocene scallop GigantopectenA living Glaucomys, or New World flying squirrelA living Glaucomys sabrinus, or northern flying squirrelIllustration of a living Globicephala macrorhynchus, or short-finned pilot whaleShell of a Glyphostoma sea snailA living Gopherus polyphemus, or gopher tortoiseA living Graptemys barbouri, or Barbour's map turtleA living Grus americana, or whooping craneFossil of the Cambrian echinoderm GogiaFossil of the Cambrian echinoderm GogiaFossil of the Middle-Late Devonian trilobite GreenopsFossilized skeleton of the Carboniferous four-limbed animal precursor GreererpetonRestoration of the Carboniferous four-limbed animal precursor GreererpetonFossils of the Middle Ordovician-Early Devonian trilobite GravicalymeneRestoration of the Late Cretaceous bony fish GillicusA living Gopherus, or gopher tortoiseIllustration of shells of deceased Globigerina and related foraminiferans as seafloor "Globigerina ooze"A living Glyptemys muhlenbergii, or bog turtleA living Gulo gulo, or wolverineFossilized leaf of the Permian-modern tree GinkgoFossilized skeleton of the Middle Jurassic-Late Cretaceous mammal GobiconodonLife restoration of the Late Cretaceous tyrannosaur GorgosaurusRestoration of the Late Cretaceous duck-billed dinosaur GryposaurusA living Gaillardia, or blanket flowerFossilized head of the Cambrian trilobite GlyptagnostusFossil of the Cambrian trilobite GlyptagnostusFossilized shell of the Triassic ammonoid cephalopod GymnitesLife restoration with inset scale diagram of the bird GastornisFossil tube of the Jurassic-modern polychaete worm GlomerulaRestoration of the Late Triassic theropod dinosaur GojirasaurusFossilized shell of the Middle Ordovician-Middle Devonian nautiloid cephalopod GeisonocerasFossilized shell of the Middle Devonian nautiloid cephalopod GoldringiaIllustration of a living Gadus morhua, or Atlantic codA living Globicephala, or pilot whaleFossilized foliage of the Early Cretaceous-Pleistocene conifer Glyptostrobus europaeusVarious conodont elements, including those of Gnathodus (specimens 9 and 12)Fossilized teeth of the conodont GnathodusFossils of the Carboniferous coral Gymnophyllum, also known as button coralFossil of the Cambrian trilobite GenevievellaA living Graptemys, or map turtleShell of a Gastrocopta armifera land snail, or armed snaggletoothRestoration of the Pleistocene armadillo relative GlyptodonRestorative portrait of the Eocene-Oligocene bear dog GustafsoniaRestorative portrait of the Late Cretaceous duck-billed dinosaur Gryposaurus.Restoration of the Permian frog precursor GerobatrachusFossilized shell of the Carboniferous-Permian brachiopod Gypospirifer condorIllustration of a living Galerita ground beetleFossilized skeleton of the Eocene bird GallinuloidesFossilized skull of the Late Jurassic long-necked dinosaur GaleamopusFossilized skeleton of the Late Jurassic armored dinosaur GargoyleosaurusA living Gyrinophilus porphyriticus, or Spring salamanderRestoration of the Middle Devonian-Carboniferous acanthodian ("spiny shark") GyracanthusFossilized skeletons of the Early Cretaceous armored dinosaur GastoniaFossilized skeleton of the Late Cretaceous duck-billed dinosaur GryposaurusIllustration of a living Gadus, or codIllustration of a living Geomys, or eastern pocket gopher
Fossilized skull of the Middle Triassic amphibian Hadrokkosaurus
Life restoration of the Late Triassic crocodile relative Hesperosuchus
Restoration of Pliocene-Pleistocene Homotherium, or scimitar cat
Fossilized shell of the Late Cretaceous ammonoid cephalopod HoploscaphitesRestoration of the Permian Chimaera relative HelicoprionA living Haliotis, or abaloneThe iridescent interior of a shell of a Haliotis, or abaloneFossilized shell of the Late Cretaceous ammonoid cephalopod HauericerasFossilized shell of the Triassic ammonoid cephalopod HedenstroemiaFossilized shell of the Middle Jurassic-Early Cretaceous sea urchin HemicidarisFossilized teeth of the Cretaceous-modern cow shark genus HeptranchiasFossilized skeleton of the Permian-Late Cretaceous shark HybodusFossilized skeleton of the Permian-Late Cretaceous shark HybodusA living Haminoea bubble sea snailFossilized skull of the mesonychian mammal HarpagolestesA living Heloderma, the genus including the Gila monster and beaded lizardsFossilized skeleton of the Eocene-Miocene mammal HerpetotheriumLife restoration of the Eocene-Miocene mammal HerpetotheriumA living Calomys (formerly Hesperomys), or vesper mouseA living Hexagrammos greenlingIllustration of a living Hexanchus, or sixgill sharkRestoration of a herd of the Pliocene-Holocene horse Hippidion. Robert Bruce Horsfall (1913).Restoration of the Eocene-Miocene creodont mammal HyaenodonLife restoration of the Miocene horse Hypohippus. Heinrich Harder (1920).Flowers of a living Halesia, or silverbellRestoration of the Paleocene-Eocene mesonychian mammal Hapalodectes (below)Restoration of the Paleocene-Eocene mesonychian mammal HapalodectesIllustration of a living Hellwigia wasp (upper left)Two living Helophorus beetlesRestoration of the Eocene tapir relative HeptodonA living Heriades mason beeLife restoration of HesperocyonA living Heterodon nasicus, or Western hognose snakeHeyderia fungus growing among mossFossilized skull of the Eocene tapir-like mammal HomogalaxDiagram illustrating the life cycle of a Hoplocampa sawflyLiving Hydrangea flowersA living Hydrobius fuscipes water scavenger beetleA living Hygrotus predaceous diving beetleA living Hylobius weevilLife restoration of the Eocene odd-toed ungulate HyopsodusFossilized skeleton of the Eocene odd-toed ungulate HyrachyusRestoration of the Eocene-Oligocene odd-toed ungulate Hyracodon. Charles R. Knight (1896).Restoration of the Late Triassic reptile Hypsognathus.Fossilized teeth of the Miocene weasel shark Hemipristis serraA living Halichoeres wrasseLiving Halimeda green algaeA preserved Heliaster microbrachius sea starA living Heterodon simus, or southern hognose snakeA living Himantopus, or stiltFossilized skeleton of the Miocene-Pliocene horse HippotheriumRestoration of the Pleistocene armadillo relative Holmesina with a human to scaleShell of a Hyalina margin sea snailA living Hydrochoerus, or capybaraLife restoration of the Cambrian brachiopod relative HaplophrentisFossilized shells of the Cambrian brachiopod relative HaplophrentisFossils of the burrow ichnogenus HelminthopsisFossils of the burrow ichnogenus HelminthopsisLiving Hypoxylon fungusFossil of the Jurassic-Paleogene lobster HoplopariaA living Pseudacris crucifer (formerly Hyla crucifer), or spring peeperFossil of the Cambrian mollusc Halkieria.Illustration of a fossilized partial cranium of the Eocene odd-toed ungulates HyracotheriumShells of Helisoma anceps, or two-ridge rams-horn freshwater snailsRestoration (bottom) of the Carboniferous "antlered" Chimaera relative HarpagofututorFossilized tooth-whorl of the Carboniferous Chimaera relative HelicoprionFossilized skeleton of the Late Cretaceous duck-billed dinosaur HypacrosaurusLife restoration of the Late Cretaceous duck-billed dinosaur HypacrosaurusFossilized skull of the Oligocene lizard HelodermoidesIllustration of a living Hiodon, or mooneyeFoliage and flowers of a living Holmskioldia or Chinese hat plantFossilized skeleton of the Eocene-Miocene even-toed ungulate HypertragulusLife restoration of the Eocene-Oligocene false saber-toothed cat Hoplophoneus. Robert Bruce Horsfall (1913).Restoration of the Carboniferous Chimaera relative HelicoprionReplica of the fossilized tooth whorl of the Carboniferous Chimaera relative HelicoprionFossilized tooth whorl of the Carboniferous Chimaera relative HelicoprionRestoration of the Middle Ordovician trilobite HypodicranotusFossil of the Cambrian trilobite Holmia. Kiaer (1916).Life restoration of the Late Cretaceous duck-billed dinosaur HadrosaurusLife restoration of the Late Triassic primitive reptile HypsognathusLife restoration of the Late Triassic drepanosaur HypuronectorRestoration of the Late Devonian eurypterid ("sea scorpion") HallipterusLife restoration of the Late Devonian eurypterid ("sea scorpion") HallipterusFossil of the Silurian eurypterid ("sea scorpion") HardieopterusFossil of the Late Ordovician-Middle Devonian HomalonotusRestoration in multiple views of the Silurian eurypterid ("sea scorpion") HughmilleriaRestoration of the Silurian eurypterid ("sea scorpion") HughmilleriaFossils of the Silurian eurypterid ("sea scorpion") HughmilleriaA living Haematopus palliatus, or American oystercatcherA living Heliornis fulica, or SungrebeA living Histrionicus histrionicus, or harlequin duckFossilized vertebra of the Late Cretaceous duck-billed dinosaur HypsibemaA living Humulus, or hop plantLife restoration of the Eocene-Oligocene dog Hesperocyon. Robert Bruce Horsfall (1913).Fossil of the Early Devonian trilobite HuntoniatoniaFossilized mandible of the Eocene horse HaplohippusFossil of the Cambrian sponge HazeliaRestoration of the Middle-Late Devonian placoderm fish HolonemaFossil of the Late Devonian-Carboniferous lobe-finned fish HoloptychiusRestoration of the Late Devonian four-limbed animal precursor HynerpetonA living Halichoerus grypus, or grey sealRestoration of the Eocene-Oligocene manatee relative HalitheriumLife restoration of the Late Cretaceous mosasaur HainosaurusFossilized skeleton of the Early Jurassic bony fish HulettiaIllustration in multiple views of a fossilized shell of the Silurian mollsuc Helcionopsis striataFossil of the Cretaceous-Miocene crab HarpactocarcinusLife restoration of the Pleistocene pronghorn HayocerosShell of Haminoea bubble shell sea snailIllustration in multiple views of fossilized shells of the Late Cretaceous ammonoid cephalopod Didymoceras navarroensisA living Homarus lobsterFossil of the Late Cretaceous lobster Hoploparia bearpawensisLiving Hydnophora coralFossil of the Permian worm-like possible mollusc HelicoconchusAssemblage of fossils of the Permian worm-like possible mollusc HelicoconchusFossilized shells of the Cambrian brachiopod relative HaplophrentisLife restoration of the Late Cretaceous oviraptorosaur HagryphusRestoration of the Early Cretaceous Iguanodon relative HippodracoLife restoration of the Late Jurassic crocodilian relative HoplosuchusKnown material diagram of the Middle-Late Triassic distant crocodilian relative HeptasuchusRestoration of the Late Jurassic stegosaur HesperosaurusRestoration of the Late Triassic rhynchosaur HyperodapedonFruit of a Hovenia treeA living Hydrobius water scavenger beetleRestoration of the Eocene odd-toed ungulate HyrachyusLife restoration of the Late Cretaceous ammonoid cephalopod Hamites
A living Iridomyrmex, or rainbow antFossil of the Middle Ordovician trilobite IllaenusDiagram illustrating two specimens of the Late Cretaceous toothed bird Ichthyornis with an anachronistic human to scaleRestoration of a pod of the Late Triassic-Early Jurassic ichthyosaur IchthyosaurusLiving Isognomon marine bivalvesRestoration of the Miocene walrus ImagotariaFossilized skeleton of the Eocene-Oligocene rodent IschyromysA living Isurus oxyrinchus, or shortfin mako sharkFoliage and fruit of a living Ilex, or hollyFossilized skull of the Eocene-Oligocene rodent IschyromysA living Isomira comb-clawed beetleIllustration of a living Ameiurus catus (formerly Ictalurus catus), or white bullheadA living Ixobrychus exilis, or least bitternLife restoration of the Carboniferous Chimaera relative IniopteryxFossil of the Middle-Late Ordovician trilobite Isotelus.Restoration of the Carboniferous synapsid (mammal precursor) IanthasaurusIllustration of a living Ameiurus melas (formerly Ictalurus melas), or Black bullheadIllustration of a living Ictiobus, or buffalo fishIllustration of a living Ictalurus catfishFossilized skeleton of the Middle Jurassic-Miocene Chimaera relative IschyodusShells of Ischadium recurvum, or hooked musselsDiagram illustrating the anatomy of a living Isoetes, or quillwortRestoration of the Late Triassic gliding reptile IcarosaurusFossilized teeth of the Late Cretaceous-modern Isurus, or mako sharkShells of Tritia trivittata threeline mud sea snailA modern Isistius dogfishA living Istiophorus platypterus, or Indo-Pacific sailfishFossilized shell of the Late Jurassic ammonoid cephalopod IdocerasKnown material diagram of the Early Cretaceous Iguanodon relative IguanacolossusRestoration of the Early Cretaceous Iguanodon relative IguanacolossusFruit of a living Illicium, or star aniseFossilized skeleton of the Eocene bat IcaronycterisFossilized shells of the Silurian nautiloid cephalopod InversocerasA living Icterus spurius, or orchard orioleA living Istiophorus , or sailfish
Fossilized shell of the Late Cretaceous ammonoid cephalopod Jeletzkytes
Living Juncus, or rushesA living Juniperus, or juniper treeA living Juglans, or walnut treeA living Junco hyemalis, or dark-eyed juncoA living Jabiru mycteria storkA living Jordanella floridae, or American flagfishRestoration of the Carboniferous-Permian ray-like cartilaginous fish Janassa (top and left)Life restoration of the Late Cretaceous horned dinosaur JudiceratopsA living Juglans regia also known as the Persian or English walnutRestoration of the Late Cretaceous primitive duck-billed dinosaur JeyawatiA living Juniperus virginiana, also known as red cedar or eastern juniperFossilized skeleton of the Eocene wading bird Juncitarsus
Fossilized shells of the Jurassic brachiopod KallirhynchiaFossilized shell of the Early Cretaceous ammonoid cephalopod KossmaticerasShell in multiple views of a Kelletia kelletii, or Kellet's whelkRestoration of the Oligocene-Miocene dolphin KentriodonClose-up of the tip of a branch of a Keteleeria conifer treeFlowers of a living Kalmia shrubA living Kinosternon subrubrum, or eastern mud turtleShell of a Kurtziella cerina sea snailRestoration of the Silurian eurypterid ("sea scorpion") KokomopterusPhosphate nodules containing fossils of the Carboniferous Chimaera relative KawichthysA living Kinosternon flavescens, or yellow mud turtleFossil of the Cambrian trilobite KendallinaRestoration of the Late Cretaceous duck-billed dinosaur KritosaurusRestoration of the Oligocene-Miocene horse KalobatippusRestoration of the Late Triassic amphibian KoskinonodonIllustration of a modernKogia breviceps, or pygmy sperm whaleA living Kajikia albida, or white marlinFossils of the Early Devonian trilobite KainopsFossilized heads of the Silurian eurypterid ("sea scorpion") Kiaeropterus (specimens 1-8)Shells of Kurtziella sea snailsFossilized skeleton of the Late Triassic amphibian KoskinonodonLife restoration at various ages of the Late Triassic amphibian Koskinonodon with an anachronistic human to scaleDiagram illustrating the size of the Late Jurassic long-necked dinosaur Kaatedocus with an anachronistic human to scaleFossilized skeleton of the Eocene bony fish KnightiaRestoration of the Late Cretaceous horned dinosaur Kosmoceratops
A living Lepus alleni, or antelope jackrabbitFossil of the Ordovician trilobite LonchodomasFossil of the Ordovician trilobite LonchodomasFossilized shell of the Cretaceous ammonoid cephalopod Lytoceras batesiShell in multiple views of a Labyrinthus land snailShell of a Laevicardium elatum, or giant egg cockleLiving Lagenorhynchus dolphinsRestoration of the Miocene opah fish Lampris zatimaA living Larus californicus, or California gullA living Atractosteus spatula (formerly Lepisosteus spatula), or alligator garIllustration of a fossilized skull of the Oligocene-Miocene dog LeptocyonRestoration of the Eocene-Oligocene even-toed ungulate LeptomeryxA living Leptopecten latiauratus, or kelp scallopA living Lepus americanus, or snowshoe hareLepus californicus, or black-tailed jackrabbitTop view of a fossilized skull of the Eocene creodont mammal LimnocyonA living Limosa fedoa, or marbled godwitA pod of living Lissodelphis borealis, or right whale dolphinsLife restoration of the Paleocene-Eocene bird LithornisA living Littorina scutulata periwinkleRestoration of the Miocene marine drumfish LompoquiaRestoration of the Miocene bluefish relative LopharShell of a Lottia scabra, or rough limpetUnderside of a Luidia sea starFossilized skull of the Eocene carnivoran mammal LycophocyonFrond of a living Lygodium, or climbing fernRestoration of the Permian reptile precursor LimnoscelisA living Lagopus leucura, or white-tailed ptarmigan, in full summer plumageA living Larus gullA living Lasiopodomys voleA living LasiusA living Lebia, or colorful foliage ground beetleRestoration of the Oligocene-Miocene oreodont mammal LeptaucheniaRestoration of the Oligocene-Miocene oreodont mammal LeptaucheniaFossilized skeleton of the even-toed ungulate LeptomeryxA living Leptostylus longhorn beetleA living Lepus townsendii, or white-tailed jackrabbitA living Limnephilus caddisflyBerries and foliage of a living LinderaFlowers of a living LinnaeaA living Linyphia sheet weaver spiderPreserved Liometopum antRestoration of the Eocene butterfly LithodryasFlowers of a living LomatiaIllustration of various living flea beetles, including Longitarsus (first member of third row)Pair of living Lontra canadensis, or North American river otterA living Lycosa wolf spiderA living Lygaeus seed bugA living Lytta blister beetleA living Lachnolaimus maximus, or hogfishA living Lagodon rhomboides, or pinfishA living Lasiurus, or hairy-tailed batIllustration of a living Laterallus exilis, or grey-breasted crakeA living Leiostomus xanthurus, or spotA living Leopardus pardalis, or ocelotA living Leopardus wiedii, or margayA living Lepidochelys, or ridley sea turtleA living Limnodromus scolopaceus, or long-billed dowitcherShell of a Linatella triton sea snailShell of a Liotia sea snailShell of a Lithopoma americanum turban sea snailA living Littoraria angulifera, or mangrove periwinkleA living Lophodytes cucullatus, or hooded merganserShells of Lucapina sowerbii, or Sowerby's fleshy limpetA living Lutjanus snapperA living Lytechinus variegatus, also known as the green or variegated sea urchinFossil in cross section of the Carboniferous seed fern stem LyginopterisA living Lactophrys boxfishA living LeopardusIllustration of a fossil of the Carboniferous centipede LatzeliaFossilized bark of the Carboniferous-Late Triassic club moss relative Lepidodendron, also known as the scale treeLife restoration of the Permian snake-like amphibian Lysorophus showing speculative egg-coiling behaviorRestoration of the Carboniferous-Early Triassic cartilaginous fish ListracanthusIllustration of a living Lepisosteus platostomus, or shortnose garA living Lepomis humilis, or orangespotted sunfishLiving Lactarius mushroomsShells in multiple views of Latiaxis coral sea snailsFossilized skull and vertebrae of the Permian snake-like amphibian LysorophusLiving Libinia crabsShell of a Limecola balthica, or Baltic clamFossilized skeleton of the Early Jurassic-Late Cretaceous bony fish LepidotesRestoration of the Late Cretaceous primitive horned dinosaur LeptoceratopsFossilized foot bones of the Late Cretaceous oviraptorosaur LeptorhynchosFossilized skeleton of the Eocene-Oligocene LeptictisA living Lepomis microlophus, or redear sunfishPortrait living Lontra ottersLiving Lycopodium, or ground pine clubmossesFossil of the Late Ordovician-Middle Devonian trilobite LeonaspisFossilized skull of the Late Cretaceous alligator relative LeidyosuchusPartial fossilized jaws of the Late Cretaceous mosasaur LiodonIllustration of a living Libinia emarginata, or portly spider crabLiving Lunularia, or crescent-cup liverwortA living Loxia curvirostra, or red crossbillFossils of the Middle Devonian clubmoss LeclercqiaRestoration of the Early Ordovician nautiloid cephalopod LevisocerasA living Leucophaeus atricilla, or laughing gullMounted skeleton of a Lophius americanus, or American anglerfishA living Lopholatilus chamaeleonticeps, or great northern tilefishLife restoration of the Permian reptile LabidosaurikosLife restoration of the Permian reptile LabidosaurusFossilized skeleton of the Permian reptile LabidosaurusLife restoration of the Permian amphibian LlistrofusFossilized shell of the Early Cretaceous ammonoid cephalopod LyellicerasIllustration of shells in multiple views of Lacuna vincta, or northern lacuna sea snailsA living Lepus, or hareA living Limnodromus griseus, or short-billed dowitcherA living Lytechinus sea urchinA living Lithobates pipiens (sometimes Rana pipiens), or northern leopard frogIllustration of a living Lepomis sunfishFossilized skull of the Early Jurassic-Late Cretaceous bony fish LepidotesShells in differing orientation of a Littorina sea snail, or periwinkleA living Lasionycteris noctivagans, or silver-haired batA living Lasiurus borealis, or eastern red batShell of a Lovenia sea urchinA living Lymnaea (larger) freshwater snail, or Melantho snailFile:Leptorhynchos elegans.jpgFossilized foot bones of the Late Cretaceous oviraptorosaur LeptorhynchosFossilized shell of the Late Cretaceous ammonoid cephalopod LewesicerasFossilized skull of the Late Cretaceous plesiosaur LibonectesRestoration of the Late Cretaceous plesiosaur Libonectes with an anachronistic scuba diver to scaleFossilized skeleton of the Late Triassic aetosaur LongosuchusRestoration of the Late Triassic aetosaur LongosuchusFossil of the Cambrian arthropod LeanchoiliaRestoration in multiple views of the Cambrian arthropod LeanchoiliaA living Lagopus, or ptarmiganFossilized skeleton of the Eocene freshwater frigatebird LimnofregataA living Lynx lynx, or Eurasian lynxIllustrative skeletal reconstruction of the Late Cretaceous primitive horned dinosaur LeptoceratopsRestoration of the Late Cretaceous tyrannosaur LythronaxRestoration of the Cambrian possible sea snail LatouchellaLiving Lagopus muta, or rock ptarmiganA living Larus hyperboreus, or glaucous gullShell of a Leptoxis freshwater snailA living Lithobates sylvaticus (formerly Rana sylvaticus), or wood frogIllustration of two modern species of Laccophilus water beetles
Fossilized shell of the Permian ammonoid cephalopod MetalegocerasAssemblage of fossilized shells of the Late Cretaceous ammonoid cephalopod MenuitesFossilized shell of the Late Cretaceous-Paleogene sea urchin MicrasterRestoration of the Pliocene-Pleistocene Miracinonyx, or American cheetahFossilized shell of the Middle Jurassic ammonoid cephalopod MacrocephalitesFossilized shell of the Late Cretaceous ammonoid cephalopod MantellicerasCollection of Margarella sea snailsFossilized shell of the Early-Late Cretaceous ammonoid cephalopod MariellaA living Mediaster sea starFossilized shell of the Early Cretaceous ammonoid cephalopod MortonicerasFossilized shell of the Early Cretaceous ammonoid cephalopod MortonicerasFossilized cranium of the Miocene-Pleistocene saber-toothed cat MachairodusRestoration of the Oligocene toothed-whale Macrodelphinus (background)Living Madrepore coralFoliage and berries of a Mahonia shrubA living Makaira or marlinTwo views of a shell of a Malea ringens, or grinning tunDiagram illustrating various Mammuthus species with a human to scaleReconstructed skeleton of a Mammuthus exilis, or pygmy mammothA living Martes, or martenA taxidermied Megachasma pelagios, or megamouth sharkFossilized skull and limb bones of the Miocene horse MegahippusA living Megaptera novaeangliae, or humpback whaleRestoration of the Eocene mammal Meniscotherium. Robert Bruce Horsfall (1913).Restoration of the Miocene rhinoceros MenocerasA living Mergus serrator, or red-breasted merganserIllustration of a living Merluccius productus, or north Pacific hakeRestoration of the Miocene pronghorn Merriamoceros with an anachronistic human to scaleRestoration of the Miocene three-toed horse MerychippusFossilized skeleton of the Miocene pronghorn MerycodusSkull fossils of the Oligocene-Miocene dog MesocyonLife restoration of the Eocene-Oligocene horse Mesohippus. Heinrich Harder (c. 1920).Fossilized skeleton of the Miocene-Pleistocene manatee relative MetaxytheriumRestoration of the Paleocene-Eocene mammal MiacisA living Microdipodops, or kangaroo mouseA modern Microgadus, or tomcodA living Microtus californicus, or California voleFossils of the Eocene-Oligocene three-toed horse MiohippusRestoration of Miohippus (middle) and other Oligocene animalsFossilized skull (top) and interpretive line drawing (middle) of the Miocene auk relative Miomancalla compared with the skull of a Holocene Pinguinus impennis, or great aukA living Mirounga angustirostris, or northern elephant sealA living Mitra idae, or Ida's miter sea snailShells of Alia carinata, or carinate dove shell sea snailsExterior (left) and interior of the shell of a Modiolus capax, or fat horsemusselShell in multiple views of a Monoplex triton sea snailFossilized skeleton of the Miocene chalicothere mammal MoropusA living Mustela frenata, or long-tailed weaselIllustration of a living Myctophum lanternfishLiving Mytilus californianus, or california musselsShell of a Myurella augur sea snailFossilized skeleton of the Eocene mammal MacrocranionRestoration of the Eocene mammal MacrocranionA living Malus, or wild apple, in bloomLife restoration of the Eocene brontothere mammal MegaceropsRestorative portrait, reconstructed skull, and actual fossil of the Miocene weasel relative MegalictisA living Mellinus wasp with preyA living Melospiza lincolnii, or Lincoln's sparrowRestoration of the Eocene mammal MesonyxRestoration of the Eocene pangolin relative MetacheiromysA living Microtus longicaudus, or long-tailed voleA living Microtus ochrogaster, or prairie voleRestoration of the Eocene opossum relative MimoperadectesLife restoration of the Eocene-Oligocene oreodont mammal MiniochoerusFossil of the Oligocene ant MiomyrmexA living Mordella tumbling flower beetleA living Mordellistena tumbling flower beetleA living Mustela nigripes, or black-footed ferretA pair of living Myrmica antsCollection of Mercenaria mercenaria, also known as hard clams or quahogsShell of a Macoma tenta, or narrowed macoma clamShell of a Macrocallista maculata, or calico clamA living Macrochelys temminckii, or alligator snapping turtleA living Macrocypraea cervus, or Atlantic deer cowryA living Magnolia virginiana, or sweetbay magnoliaLiving Manicina stony coralA living Margaretta flowerShell of a Marsupina bufo, or chestnut frog shell sea snailShell of a Massyla nutmeg sea snailFossilized skeleton of the Pliocene-Pleistocene saber-toothed cat MegantereonA living Melanerpes erythrocephalus, or red-headed woodpeckerShell in multiple views of a Melongena melongena, or Caribbean crown conchA living Melospiza georgiana, or swamp sparrowRestoration of the Eocene-Oligocene oreodont mammal Merycoidodon. Heinrich Harder (1920).A living Microhyla, or rice frogIllustration of a living Micropterus, or black bassA living Micrurus fulvius, or eastern coral snakeLiving Millepora alcicornis, or sea gingerA living Mimus polyglottos, or northern mockingbirdShell of a Modiolus americanusA living Modulus modulus, or tulip musselA living Molothrus ater, or brown-headed cowbirdShell in multiple views of a Monoplex parthenopeus, or giant tritonA living Mormoops megalophylla, or ghost-faced batShell of a Morum oniscus harp sea snailA living Mugil mulletShell in multiple views of a Muricanthus murex sea snailShell of a Muricopsis murex sea snailLiving Mussa angulosa, or spiny flower coralLiving Mussismilia stony coralRestoration of the Pleistocene-Holocene ground sloth Mylodon with an inset depicting its excrement and a skin fragmentA living Myotis grisescens, or gray batA living Myrica cerifera, or southern wax myrtleA heap of modern Modiolus, or horsemusselsFossilized shell of the Devonian-modern marine bivalve Modiolus, or horsemusselRestoration of the Pliocene-Holocene ground sloth Megatherium. Robert Bruce Horsfall (1913).A living Mephitis mephitis, or striped skunkA living Microtus pinetorum, or woodland voleRestoration of the mysterious Cambrian life-form MargaretiaRestorative model of the Pliocene-Pleistocene saber-toothed cat MegantereonFossilized skull of the Late Cretaceous plesiosaur MegacephalosaurusFossilized skull of the Late Cretaceous plesiosaur MegacephalosaurusRestoration of a herd of the Eocene-Miocene oreodont mammal MerychyusLiving Myripristis soldierfishesFossilized skeleton of the Pliocene-Holocene elephant relative Mammuthus, or mammothRestoration of two of the Late Cretaceous MosasaurusShell of the marine bivalve Mya truncata, also known as the blunt gaper or truncate softshellA living Marmota monax, or groundhogShells of Modiolus modiolus, or northern horsemusselsRestorative model of the Cambrian velvet worm Microdictyon.Fossilized plates of the Cambrian-Early Ordovician chiton MattheviaRestoration of the Eocene-Miocene swamp rhinoceros Metamynodon. Charles R. Knight (1896).Fossil of the Cambrian-Silurian trilobite MegistaspisRestoration of the Late Cretaceous duck-billed dinosaur MaiasauraRestoration of the Late Cretaceous horned dinosaur MedusaceratopsRestoration of the Late Cretaceous horned dinosaur MercuriceratopsLife restoration of the Early Cretaceous oviraptorosaur MicrovenatorFossilized skeletons of the Late Cretaceous pterosaur MontanazhdarchoRestoration of the Late Cretaceous primitive horned dinosaur MontanoceratopsRestoration of battling males of the Eocene brontothere mammal MegaceropsFossilized skeleton of the Eocene-Miocene oreodont mammal MerychyusRestorative portrait of the Oligocene-Miocene oreodont mammal MerycochoerusFossilized skeleton of the Miocene-Pleistocene saber-toothed cat MetailurusFossil of the Early Ordovician trilobite MegalaspidesFossils of the Cretaceous theropod dinosaur egg oogenus MacroelongatoolithusFossils of the Cretaceous theropod dinosaur egg oogenus MacroelongatoolithusDiagram illustrating the Middle Triassic ichthyosaur Mixosaurus with an anachronistic human to scaleRestoration of the Middle Triassic ichthyosaur MixosaurusFossilized shell of the Middle Triassic ammonoid cephalopod MonophyllitesA living Myotis velifer, or cave myotisRestoration of the Silurian eurypterid ("sea scorpion") MixopterusFossil of the Silurian eurypterid ("sea scorpion") MixopterusA living Makaira nigricans, or Atlantic blue marlinLiving Marchantia liverwortsA living Metasequoia, or dawn redwoodA living Istiompax indica, or black marlinA living Maretia heart urchinIllustration of a living Melanogrammus aeglefinus, or haddockA modern Merluccius albidus, or offshore hakeIllustration on a stamp of a living Mesoplodon, or mesoplodont whaleIllustration of a living Microgadus tomcodA living MobulaA living Monodon monoceros, or narwhalA living Mycteroperca groupA living Myriophyllum, or watermilfoilFossilized cranium and interpretive illustration of the Permian primitive reptile Macroleter (B)Life restoration of the Permian primitive reptile MacroleterRestoration of the Permian primitive reptile MacroleterLife restoration of the Permian amphibian MicraroterLife restoration of the Permian synapsid (mammal precursor) MycterosaurusRestoration of the Permian synapsid (mammal precursor) MycterosaurusFossilized skeleton of the Middle Triassic amphibian MastodonsaurusA living Mustela, or weaselShell in multiple views of a Meiocardia marine bivalveShell in multiple views of a Microdrillia sea snail
Restoration of the Late Triassic reptile MalerisaurusIllustration of a shell of the freshwater snail MadagasikaraFossil of the Late Cretaceous-Eocene sea urchin MicrasterShell of a Monodonta top sea snailFossil of the Cambrian cyanobacterium MarpoliaRestoration of the Eocene tree Macginitiea with insets detailing its anatomyRestorative portrait of the Eocene saber-toothed creodont mammal MachaeroidesShell in multiple views of a llving Microphysula land snailFossilized skeleton of the Eocene perch relative MioplosusFossilized jaw of the Late Jurassic crocodilian relative MacelognathusShell of a Mactra marine bivalve, also known as trough shells or duck clamsFossil of the Late Jurassic-Early Cretaceous crustaceans MecochirusRestoration of the Late Jurassic plesiosaur MegalneusaurusLife restoration of the Late Cretaceous horned dinosaur MachairoceratopsFossilized skeletons of the Early Cretaceous long-necked dinosaur MoabosaurusFossil of the Cambrian trilobite MesonacisRestoration of the Silurian trilobite MiraspisA living Morus bassanus, or northern gannetIllustration of a living Moxostoma suckerA living Mustela nivalis, or least weasel
Life restoration of the Pleistocene ground sloth Nothrotheriops
Illustration of a fossil of the head of the Cambrian trilobite NephrolenellusFossil of the Cambrian trilobite NevadellaLife restoration of the Late Triassic thalattosaurs Nectosaurus (right) and ThalattosaurusKnown material diagram of the skull of the Late Triassic thalattosaur NectosaurusOpalized guard of the belemnoid cephalopod NeohibolitesShell of a Narona clavatula nutmeg sea snailA living Nassarius fossatus, or channeled basket snailFossilized skeleton of the Pleistocene Odocoileus lucasi, or American mountain deerFossilized skeleton of the Pleistocene Old World vulture NeogypsFossilized skeleton of the Miocene aquatic mammal NeoparadoxiaFossilized skeleton of the Miocene NeophrontopsA living Nicrophorus marginatus burying beetleFossilized partial cranium of the Miocene saber-toothed cat NimravidesFossilized skull of the Oligocene false saber-toothed cat NimravusFossilized skeleton of the Pleistocene ground sloth NothrotheriopsShell of Notoacmea limpetA living Notorynchus cepedianus, or broadnose sevengill sharkA living Numenius phaeopus, or whimbrelA living Nephila, or golden silk orb-weaverFossilized skeleton of the Eocene primate NotharctusFossilized skull of the Eocene primate NotharctusA living Notonecta, or common backswimmerA living Numenius madagascariensis, or far eastern curlewA living young Bubo scandiacus (formerly Nyctea scandiaca), or snowy owlFlower of a living NymphaeaA living Nysius false chinch bugIllustration of a living Notorynchus cow sharkShell in multiple views of a Nannodiella sea snailShell of a Nassarina dove sea snailShells in differing orientations of a Phrontis antillara (formerly Nassarius antillarum), or the Antilles nassa sea snailShells of Phrontis vibex (formerly Nassa vibex), or bruised nassa sea snailsA living Nasua, or coatiShell in multiple views of a Naticarius canrena moon sea snailA living Nerodia cyclopion, or green water snakeA living Necturus, or mudpuppyIllustration of the recently extinct Neomonachus tropicalis, or Caribbean monk sealA living Nerodia fasciata, or banded water snakePreserved Neverita moon sea snailShell of a Niveria suffusa false cowrieShells of a Nodipecten nodosus, or lion's paw scallopA living Notophthalmus viridescens, or eastern newtA living Numenius americanus, or long-billed curlewExterior and interior of a Nummulite viewed from aboveA living Nyctanassa violacea, or yellow-crowned night heronShell in multiple views of a Nerita polita sea snailA living Negaprion brevirostris, or lemon sharkFossilized shell of the Middle Jurassic ammonoid cephalopod NormannitesFossilized frond of the Carboniferous seed fern NeuropterisIllustrations of fossilized foliage of the Carboniferous-Permian plant NoeggerathiaRestoration of the Late Cretaceous pterosaur NyctosaurusLiving Nassella, or needlegrassA living Notropis, or eastern shinerShell of a Niso sea snailShell in multiple views of a Neptunea despecta whelk sea snailA living Neovison vison, or American minkA living Napaeozapus insignis, or woodland jumping mouseA living Neofiber, or round-tailed muskratA living Nerodia sipedon, or northern water snakeIllustration of a Navicula diatom algaFossilized skeleton of the Late Cretaceous-Eocene bony fish NotogoneusA living Nelumbo lotusA living Nuphar water lilyA living Nerodia rhombifer, or diamondback water snakeFossil of the Cambrian trilobite NephrolenellusFossilized head of the Cambrian trilobite NephrolenellusFossil of the Cambrian trilobite NevadiaFossilized shell of the Triassic bivalve NeomegalodonFossilized foliage of the Triassic-Middle Jurassic horsetail relative NeocalamitesFossilized shell of the Late Cretaceous-Quaternary oyster NicaisolophaRestoration of the Late Cretaceous therizinosaur NothronychusA living Neotoma micropus, or southern Plains woodratA living Nitzschia diatomIllustration of a living Numenius borealis, or Eskimo curlew. Archibald Thorburn.Anatomy of a de-shelled Nototeredo shipwormA living NautilusShell of a Nodipecten marine scallopA living Nelumbo lotusA living Nectandra tree, or sweetwoodA living Neotamias cinereicollis, or gray-collared chipmunkA living Notophthalmus, or North American newtRestoration of the Cambrian-Silurian arthropod NaraoiaFossilized skeleton of the Late Cretaceous-Eocene beaked salmon relative NotogoneusA living Nucifraga columbiana, or Clark's nutcrackerA taxidermied Numenius borealis, or Eskimo curlewFossilized jaw and ilium of the Late Jurassic herbivorous dinosaur NanosaurusFossilized skull of the Late Cretaceous tyrannosaur Nanotyrannus, possibly a juvenile Tyrannosaurus rather than a distinct genusKnown material diagram of the Late Cretaceous horned dinosaur NasutoceratopsFossilized skeleton of the Late Cretaceous NothronychusFossilized skeleton of the Eocene primate Notharctus tenebrosusA living Nocomis raneyi, or bull chub
Illustration of fossils of the Cambrian brachiopod ObolellaFossil of the Cambrian trilobite OlenellusIllustration of a fossil of the Cambrian trilobite OlenellusFossil of the Cambrian trilobite OlenellusRestoration of the Early Triassic ammonoid cephalopod OwenitesA living Oceanodroma furcata, or fork-tailed storm petrelShell of an Ocenebra murex sea snailShell of an Odostomia donilla pyram shell sea snailShell of an Oenopota tabulata sea snailThree living Olivella biplicata, or purple dwarf olive sea snailRestoration of a school of the Miocene-Pleistocene Oncorhynchus rastrosus, or saber-toothed salmonIllustration of a living Oneirodes dreamer with a close-up of its lure (upper right)A living Oreamnos americanus, or mountain goatRestoration of the Miocene pseudo-toothed bird OsteodontornisA living Oxyura jamaicensis, or ruddy duckA living Ochotona princeps, or American pikaA living Odynerus potter waspIllustration of a living Oligomerus death-watch beetleA living oligotrich ciliateA living Ophisaurus, or glass lizardA living Hydrotaea house flyA living Orchelimum katydidA living Oreamnos harringtoni, or Harrington's mountain goatFossilized skeleton of the Eocene horse OrohippusA living Orontium, or golden-clubFlowers and foliage of a living OsmanthusRestoration of the Paleocene-Eocene creodont mammal OxyaenaA living Oxycera soldier flyFossil from Dinosaur State Park and Arboretum of the Late Triassic-Middle Jurassic sauropodomorph dinosaur footprint ichnogenus OtozoumShell of a Odostomia laevigata, or ovoid odostome sea snailShell of a Oliva reticularis, or netted olive sea snailShell in multiple views of a Oliva sayana, or lettered olive sea snailInterior and exterior of the shell of an Onustus carrier shell sea snailFossil of the Permian-modern crustacean burrow ichnogenus OphiomorphaA living Ophisaurus compressus, or Island glass lizardA living Opsanus toadfishLiving Orbicella annularis, or boulder star coralA living Oryzomys palustris, or marsh rice ratDiagram illustrating the largest (grey) and most conservative (red) size estimates of the Miocene-Pliocene shark Carcharocles megalodon (sometimes Carcharodon or Otodusmegalodon) with a whale shark (violet), great white shark (green), and anachronistic human (black) to scaleRestoration of a pair of the Oligocene-Miocene camel Oxydactylus. Robert Bruce Horsfall (1913).Fossil of the Cambrian trilobite OgygopsisAssemblage of fossils of the Cambrian trilobite OgygopsisFossilized skeleton of the Oligocene-Miocene camel OxydactylusFossil of the Carboniferous crinoid ("sea lily") OnychocrinusClose-up of a fossilized skeleton of the Carboniferous-Permian cartilaginous fish OrodusLife restoration of the Middle-Late Devonian lobe-finned fish OnychodusIllustration of a fossilized lower jaw and teeth of the Middle-Late Devonian lobe-finned fish OnychodusFossilized tooth whorl of the Middle-Late Devonian lobe-finned fish OnychodusFossilized skeleton of the Carboniferous-Permian freshwater shark OrthacanthusA living Ortalis, or chachalacaFlower, buds, and foliage of a living OperculinaA living Ostracion boxfishLife restoration of the Miocene sperm whale OrycterocetusFossil of the Cambrian trilobite OrygmaspisFossilized tooth of the Late Cretaceous giant sawfish OnchopristisFossil of the Ordovician trilobite OgygitesFossil of the Ordovician trilobite OgyginusFossilized partial cranium of the Late Cretaceous armored dinosaur OohkotokiaRestoration of the Late Cretaceous herbivorous dinosaur OrodromeusLife restoration of the Late Cretaceous herbivorous dinosaur Oryctodromeus in a burrowLiving Onoclea fernsShell in multiple views of an Oreohelix land snailPortrait of a living Ophisaurus ventralis, or eastern glass lizardIllustration of a fossil of the Cambrian trilobite OlenellusFossil preserving carbon films left by the legs and antennae of the Cambrian trilobite OlenoidesRestoration of the Cambrian priapulid worm relative OttoiaFossil of the Cambrian priapulid worm relative OttoiaFossilized teeth of the Cambrian priapulid worm relative OttoiaLife restoration of the Middle-Late Triassic ichthyosaur OmphalosaurusFossil of the Permian-modern crustacean burrow ichnogenus OphiomorphaLife restoration of the Permian synapsid (mammal precursor) OedaleopsLife restoration of the Permian amphibian OnchiodonFossilized skeleton of the Permian amphibian OnchiodonFossilized skeleton of the Carboniferous-Permian synapsid (mammal precursor) OphiacodonRestoration of the Late Cretaceous horned dinosaur OjoceratopsKnown material diagram of the Late Cretaceous oviraptorosaur OjoraptorsaurusRestoration of the Late Cretaceous ostrich dinosaur OrnithomimusRestoration of the Miocene pronghorn OsbornocerosFossil of the Silurian-Devonian trilobite OdontochileFossil of the Silurian-Devonian trilobite OdontochileIllustration of a fossil of the Cambrian trilobite OlenellusFossil teeth of Odontaspis winkleri from Khouribga (Morocco), 55-45 myaA living Odontaspis ferox, or smalltooth sand tigerA living Opsanus tau, or oyster toadfishLiving Osmunda regalis, or royal fernsRestoration of the Carboniferous-Permian synapsid (mammal precursor) OphiacodonFossilized skeleton of the Carboniferous-Permian synapsid (mammal precursor) OphiacodonFossilized tooth of the Carboniferous-Permian freshwater shark OrthacanthusA living Ochotona, or pikaA living Ocotea treeShell of an Odostomia fusulus pyram sea snailA living Onychomys torridus, or southern grasshopper mouseFossilized vertebrae of the Cretaceous sawfish OnchosaurusPartial fossilized skeleton of the Late Jurassic bony fish OphiopsisFossilized shell of the Late Cretaceous ammonoid cephalopod OstlingocerasRestoration of the Eocene bat OnychonycterisA living Oreamnos, or mountain goatFossilized skeleton of the Late Jurassic theropod dinosaur OrnitholestesRestoration of the Late Jurassic ichthyosaur OphthalmosaurusFossilized skeleton of the Late Jurassic herbivorous dinosaur OthnielosaurusFossil of the Permian-Late Cretaceous fern OsmunditesIllustration of a fossilized partial skull of the Paleocene-Eocene pseudo-toothed bird OdontopteryxA living Ovis dalli, or Dall sheep
Internal structure of the Silurian-Late Devonian tree-like probable fungus Prototaxites
"Schunnemunk tree" specimen of the Silurian-Late Devonian tree-like probable fungus PrototaxitesThin section under a light microscope showing the internal structure of the Silurian-Late Devonian tree-like probable fungus PrototaxitesRestoration with a conifer-like body plan of the Silurian-Late Devonian tree-like probable fungus Prototaxites. John William Dawson (1888).
Restoration based on the "Schunnemunk tree" fossil of the Silurian-Late Devonian tree-like probable fungus Prototaxites
Fossil of the Silurian-Middle Devonian eurypterid ("sea scorpion") Pterygotus
Restoration of the underside of the Silurian-Middle Devonian eurypterid ("sea scorpion") Pterygotus
Restoration of the Silurian-Middle Devonian eurypterid ("sea scorpion") Pterygotus
Assemblage of the Early-Middle Devonian brachiopod Paraspirifer
Fossilized tooth of the Carboniferous-Permian shark Petalodus
Fossilized shell of the Silurian-Early Triassic sea snail Platyceras
Fossilized shell of the Late Cretaceous ammonoid cephalopod Pachydiscus
Fossilized skull of the Late Cretaceous dome-headed dinosaur Pachycephalosaurus
Fossilized skeleton of the Early Cretaceous-Eocene bony fish Palaeobalistum
Illustration of a living Ptinus latro, or brown spider beetle
A living Procyon lotor, or raccoonRestoration of the Cambrian trilobite PeachellaFossil of the mysterious Ediacaran animal PteridiniumFossilized shell of the Early-Late Cretaceous ammonoid cephalopod PachydesmocerasFossilized shell of the Late Cretaceous ammonoid cephalopod Parapuzosia with a human indicating its sizeFossilized shell of the Late Cretaceous ammonoid cephalopod PeronicerasRestoration of the Late Cretaceous mosasaur Plesiotylosaurus with an anachronistic scuba diver to scaleFossilized skeleton of the Late Cretaceous mosasaur PlotosaurusRestoration of the Late Cretaceous mosasaur PlotosaurusRestoration of the Late Cretaceous mosasaur PlotosaurusShell in multiple views of a Polinices moon sea snailFossilized shell of the Paleocene-modern moon snail PolinicesFossilized shell of the Late Cretaceous ammonoid cephalopod PolyptychocerasFossilized shell of the Late Cretaceous ammonoid cephalopod PolyptychocerasShells of Potamides horn sea snailsFossilized partial skull of the Late Cretaceous mosasaur PrognathodonA close-up view of the teeth of the Late Cretaceous mosasaur PrognathodonMicroscopic views of the fibrous tissues and microstructures recovered from a humerus of the Late Cretaceous mosasaur PrognathodonSkull of Prognathodon solvayi, the type species of the genus.Fossilized skull of the Late Cretaceous mosasaur PrognathodonA side-by-side comparison of a typical "crushing" mosasaur tooth (left, Igdamanosaurus) and a typical "cutting" mosasaur tooth (right, Mosasaurus). Teeth of Prognathodon seem to contain characteristics of both.Life restoration of the Late Cretaceous mosasaur Prognathodon preying upon an ammonoid cephalopodRestoration of the Late Cretaceous mosasaur PrognathodonFossilized shell of the Early Cretaceous ammonoid cephalopod PseudothurmanniaFossilized shell of the Jurassic-Cretaceous marine bivalve PterotrigoniaFossilized skeleton of the PaleoparadoxiaRestoration of the Miocene aquatic mammal PaleoparadoxiaFossilized skull of the Miocene horse ParahippusA modern Paralichthys large-toothed floundersRestoration of the Miocene-Pliocene dolphin Parapontoporia (top)Fossilized skull of the Miocene-Pliocene dolphin Parapontoporia (left)Restoration of the Miocene baleen whale Parietobalaena and calfClose-up portrait of a living Parribacus slipper lobsterShell of a Patelloida limpetReconstruction of a fossilized skull of the Oligocene-Pleistocene pseudo-toothed bird Pelagornis, with close-up insets of its pseudo-teethA living Pelecanus occidentalis, or brown pelicanFossilized skull of the Eocene-Oligocene lizard PeltosaurusInterior of the shell of a Periglypta venus clamA living Perognathus pocket mouseA living Peromyscus truei, or pinyon mouseFossilized shell of the Oligocene-modern conch sea snail PersististrombusShells of Petricola venus clamsA living Phalacrocorax auritus, or double-crested cormorantA living Phalaropus lobatus, or red-necked phalaropeIllustration of a fossilized cranium of the Oligocene-Miocene bone-crushing dog PhlaocyonIllustration of a fossilized mandible of the Oligocene-Miocene bone-crushing dog PhlaocyonA living Phoebastria albatrus, or short-tailed albatrossTwo Phoenicopterus, or flamingosA living Phrynosoma, or horned lizardShell of a Phyllonotus murex sea snailFoliage and cones of a Pinus muricata, or bishop pineA living Piranga ludoviciana, or western tanagerA living Pitymys voleA living Plegadis chihi, or white-faced ibisRestoration of the Paleocene-Eocene primate PlesiadapisA highly camouflaged Pleuronichthys righteye flounderFossilized skull of the Miocene horse PliohippusRestoration of the Miocene walrus PliopediaFossilized partial skull of the Miocene dog-like bear relative PlithocyonA living Pluvialis squatarola, or grey ploverLiving Pocillopora, or cauliflower coralIllustration of a fossilized skull of the Oligocene false faber-toothed cat PogonodonExterior of the shell of a Polymesoda basket clamA modern Porichthys notatus, or plainfin midshipmanLiving Porites stony coralA living Prionace glauca, or blue sharkIllustration of a living Pristiophorus sawsharkFossilized tooth of the Eocene brontothere mammal ProtitanopsRestoration of the Eocene brontothere mammal ProtitanopsIllustration of a fossilized skull of the Eocene camel ProtylopusClose-up view of a fossilized shell of the Oligocene-Pliocene sea turtle PsephophorusHypothetical restoration of the Oligocene-Pliocene sea turtle PsephophorusFossilized mandible of the Miocene cat PseudaelurusFossilized shell of the Eocene-modern jewelbox marine bivalve PseudochamaA living Pseudomelatoma sea snailLiving Pseudotsuga, or Douglas firsA living Gymnura, or butterfly rayShell in multiple views of a Pteropurpura festiva, or festive murex sea snailIllustration of a fossilized skull of the Paleocene multituberculate mammal PtilodusA living Sooty shearwater (formerly Puffinus griseus), or sooty shearwaterA living Ardenna tenuirostris (formerly Puffinus tenuirostris), or short-tailed shearwaterShell of a Pusula false cowrie sea snailShell of a Pyramidella adamsi, or Adams' pyram shell sea snailRestoration of the Carboniferous-Permian sail-backed amphibian PlatyhystrixLife restoration of the Carboniferous-Permian sail-backed amphibian Platyhystrix (small, foreground) and the likewise sail-backed synapsid (mammal precursor) EdaphosaurusFossilized mandibles of the Paleocene-Eocene mesonychian mammal PachyaenaA living Paederus rove beetleIllustration of a fossilized cranium of the Eocene-Miocene carnivoran mammal PalaeogaleFossilized skull of the Oligocene rabbit relative PalaeolagusFossilized partial skull of the Paleocene-Eocene creodont mammal PalaeonictisFossilized skeleton of the Eocene mammal PalaeosinopaFossilized skeleton of the Eocene brontothere mammal PalaeosyopsRestorative model and fossilized skull of the Eocene brontothere mammal PalaeosyopsFossil of the Eocene wasp PalaeovespaFoliage and berries of a living PanaxA living Panorpa scorpionflyA living Parandra longhorn beetlesFossilized partial skull and limb bone of the Eocene-Oligocene camel ParatylopusRestoration the Eocene-Oligocene camel Paratylopus (upper right)Fruit of a living ParthenocissusIllustration of a living Passaloecus waspFossilized skeleton of the Eocene creodont mammal PatriofelisRestoration of the Eocene creodont mammal Patriofelis. Charles R. Knight (1896).A living Penthetria march flyA living Pepsis spider waspFossilized mandible of the Eocene-Miocene mammal PeratheriumModern fruit of Persea americana, or avocadosFossil of the Oligocene ant PetraeomyrmexA living Phalacrocorax, or cormorantRestoration of the Paleocene-Eocene ungulate Phenacodus. Charles R. Knight (1898).Flowers of a living Philadelphus, or mock-orangeA living Philanthus, or beewolfA living Phrynosoma douglasii, or pygmy short-horned lizardA living Phyllobius weevilA living Phyllophaga New World scarabA living Phymatodes longhorn beetleA living Pica hudsonia, or black-billed magpieA living Pimpla waspA living Platycheirus hoverflyA pair of living Plecia march fliesFossilized skeleton of the Paleocene-Eocene primate relative PlesiadapisA living Podiceps grebeFossilized skeleton of the Eocene-Oligocene camel PoebrotheriumLife restoration of the Eocene-Oligocene camel PoebrotheriumA preserved Pogonomyrmex harvester antA living Porzana carolina, or soraLiving Potamogeton pondweedIllustration of a fossil of the Eocene butterfly ProdryasFossil of the Eocene ant ProiridomyrmexA living Prosopis treeFossil of the Oligocene ant ProtaztecaFossilized skeleton of the Eocene horse ProtorohippusProtorohippusFossilized mandible of the Late Cretaceous-Paleocene mammal ProtungulatumIllustration of a branch, fruits, and flowers of a living Prunus gracilis, or Oklahoma plumA living Pseudacris, or chorus frogA living Pseudacris triseriata, or western chorus frogReplica of a fossilized cranium of the Miocene horse PseudhipparionPreserved Pseudomyrmex antFossilized skeleton of the Eocene protoceratid mammal PseudoprotocerasRestoration of the Paleocene taeniodont mammal PsittacotheriumFruits of a living Ptelea, or hoptreeA living Pterostichus ground beetleFossilized skeleton of the Paleocene multituberculate mammal PtilodusA living Ptosima jewel beetleRestoration of the Late Cretaceous pterosaur PteranodonA living Pandion haliaetus, or ospreyShell of a Parametaria dove sea snailFossilized teeth of the Eocene-Pleistocene shark Parotodus, or the false-toothed makoShell of a ParviturboA living Passerculus sandwichensis, or savannah sparrowA living Passerella iliaca, or fox sparrowClose-up portrait of a Passerina, or North American buntingA living PecariA living Pelecanus erythrorhynchos, or American white pelicanShell in multiple views of a Peristernia tulip sea snailThe appearance of a Podomys floridanus, or Florida mouse, is similar to the Peromyscus shown in this illustrationShell of a Persicula sea snailShell in multiple views of a Petaloconchus worm shell sea snailA living Petrolisthes porcelain crabA living Phoenicopterus ruber, or American flamingoShell in multiple views of a Phyllonotus pomum, or apple murex sea snailShells in differing orientations of Physa freshwater bladder snailsLiving Pinus taeda, or loblolly pinesFossilized skull of the Miocene baleen whale PiscobalaenaShell in multiple views of a Planorbella duryi, or the Seminole rams-horn freshwater snailFossilized skeleton of the Miocene elephant relative PlatybelodonA living Plegadis ibisShell in multiple views of a Pleuroploca sea snailA living Podiceps auritus, or horned grebeA living Poecilia latipinna, or sailfin mollyShell in multiple views of a Polinices lacteus, or milk moon sea snaiShells in differing orientations of Polinices hepaticus moon sea snailsShell in multiple views of a Polygyra septemvolva land snailShells in differing orientations of Polystira albida, or white giant turris sea snailsIllustration of a living Pomacea paludosa, or freshwater Florida applesnailLiving Porites porites, also known as hump or finger coralLiving Porites astreoides, or mustard hill coralA living Porphyrio martinicus, or American purple gallinuleRestoration of the Miocene deer relative ProcraniocerasShell in multiple views of a Prunum guttatum margin sea snailA living Psammechinus sea urchinA living Pseudacris ornata, or ornate chorus frogA living Pseudemys nelsoni, or Florida red-bellied cooterA living Pseudobranchus, or dwarf sirenLiving Pseudodiploria stony coralShell of a Psilaxis staircase shell sea snailShell of a Pterynotus alatus murex sea snailA living Puffinus puffinus, or Manx shearwaterFossilized shell in multiple views of a Pusula pediculusPyrazusShell in multiple views of a Pyrgospira tampaensis, or the Tampa turrid sea snailFossil of the Late Ordovician-Late Devonian trilobite PhacopsA living Peromyscus leucopus, or white-footed mouseA living Physeter macrocephalus, or sperm whaleA living Placopecten magellanicus, or Atlantic deep-sea scallopA living Pogonias cromis, or black drumA living Pseudotriton ruber, or red salamanderA living PhoebeIllustration of a fossilized shell in multiple views of the Paleozoic mollusc Pelagiella.Illustration of a fossilized shell of the Paleozoic mollusc Pelagiella.Fossil of the Middle Ordovician trilobite PliomeraPearls and interior of the shell of a Pteria, or winged oysterInteriors and exteriors of multiple shells of Pteria, or winged oystersInterior and exterior of the shell of a Pteria, or winged oysterA living Pinus, or pine treeFoliage of a living Pseudolarix, or golden larch treeFossil of the Silurian-Carboniferous crinoid ("sea lily") PeriechocrinusFossil in an enrolled posture of the Late Ordovician-Late Devonian trilobite PhacopsFossilized skeleton of the Carboniferous-Permian bony fish PlatysomusRestoration of the Carboniferous-Permian bony fish PlatysomusFossilized skeleton of the Carboniferous-Permian bony fish PlatysomusRestoration of the Carboniferous Chimaera relative PolysentorFossil of the Carboniferous insect ProtophasmaRestoration of the Carboniferous insects Protophasma and TitanophasmaFossilized skeleton of the Carboniferous snake-like amphibian PseudophlegethontiaFossilized shell of the Early-Middle Devonian brachiopod ParaspiriferLight micrograph of a Pinnularia algaLight micrograph of a Pinnularia algaAssemblage of fossils of the Late Devonian plant ProtosalviniaLight micrograph of a fossil of the Late Devonian plant ProtosalviniaCross-section through a fossilized stem of the Devonian-Permian tree fern PsaroniusRestoration of the Devonian-Permian tree fern Psaronius. Auguste Faguet (1877).Vascular anatomy of a stem of the Devonian-Permian tree fern PsaroniusFossil of the Carboniferous crustacean PeachocarisFossil of the Late Ordovician cystoid echinoderm PleurocystitesRestoration of the Late Devonian placoderm fish PtyctodusFossilized skeleton of the Permian bony fish PalaeoniscumRestoration of the Carboniferous reptile PetrolacosaurusFossilized skeleton of the Late Cretaceous sea turtle ProtostegaA living Perca flavescens, or yellow perchA living Phrynosoma cornutum, or Texas horned lizardA living Pomoxis, or crappiePetrified trunk segment of the Late Cretaceous-Miocene palm wood PalmoxylonUpper branches of a living Podocarpus conifer treeFronds of living Polypodium fernsFossilized skeleton of the Eocene bony fish PristigenysA modern Pristipomoides snapperShell of a Pterynotus murex sea snailA living Pagurus pollicaris hermit crabFossilized teeth of the Paleocene Palaeocarcharodon, or pygmy white sharkA living Perisoreus canadensis, or grey jayShell of a Petricolaria pholadiformis, or false angelwingA living Plethodon, or woodland salamanderRestoration of the Paleocene-Eocene waterfowl PresbyornisA taxidermied Prionodon, or Asiatic linsangIllustration of a living Prionotus searobinA living Puffinus shearwaterIllustration of a fossilized tooth in multiple views of the Early Cretaceous armored dinosaur PriconodonIllustration of a fossilized tooth of the Early Cretaceous armored dinosaur PriconodonFossilized partial skeleton of the Early Jurassic theropod dinosaur PodokesaurusLife restoration of the Early Jurassic theropod dinosaur PodokesaurusA living Platyrhina rayFossilized skeleton of the Late Cretaceous-Eocene bony fish PycnodusLiving Pinus strobus, or white pinesTaxidermied specimen of Pinguinus impennis, or the great aukFossilized shell of the Late Devonian ammonoid cephalopod PlatyclymeniaFossil of the Cambrian trilobite Ptychagnostus atavusFossils of the Cambrian trilobite PtychopariaRestoration of subadults of the Late Cretaceous dome-headed dinosaur Pachycephalosaurus butting headsRestoration of the Cretaceous-Pleistocene frog PalaeobatrachusIllustration of fossilized teeth of the Late Cretaceous armored dinosaur PalaeoscincusIllustration of a fossilized skull of the Late Cretaceous armored dinosaur PanoplosaurusElectron micrograph of the fossilized teeth in multiple views of the Late Cretaceous theropod dinosaur ParonychodonMicrograph of a fossilized tooth of the Late Cretaceous troodontid PectinodonFossilized skeleton of the Late Cretaceous primitive horned dinosaur PrenoceratopsFossilized skeleton of the Late Cretaceous duck-billed dinosaur ProsaurolophusFossilized mandible of the Late Cretaceous-Paleocene mammal ProtungulatumFlowers and foliage of a living PaliurusRestoration of the Paleocene pantodont mammal PantolambdaFoliage of a living Paulownia plantA living Peromyscus maniculatus, or North American deermouseStand of living Phragmites grassesRestoration of the Miocene oreodont mammal PromerycochoerusRestoration of the Late Cretaceous-Paleocene primate relative PurgatoriusSpiral-shaped fossilized burrow and associated skeleton of the Oligocene-Miocene beaver PalaeocastorA living Pantherophis obsoletus, or black rat snakeA living Parascalops breweri, or hairy-tailed moleA living Phasianus pheasantFossilized teeth of the Oligocene-Miocene oreodont mammal PhenacocoelusRestoration of a female (left) and male of the Oligocene-Miocene even-toed ungulate Protoceras. Charles R. Knight (1896).Fruit of a living Prunus maritima, or beach plumA living Pylodictis olivaris, or flathead catfishFossilized skeleton of the Triassic bony fish ParalepidotusFossilized skeleton of the Triassic bony fish ParalepidotusLife restoration of the Triassic ichthyosaur PhalarodonFossilized shell of the Early Jurassic ammonoid cephalopod PsilocerasFossilized shell of the Triassic ammonoid cephalopod PtychitesFossilized skeleton of the bony fish PtycholepisA living Pagurus hermit crabFossilized skull of the Late Cretaceous mosasaur PlioplatecarpusAmber-entombed specimen of the Late Cretaceous wasp PlumalexiusAmber-entombed specimen of the Late Cretaceous wasp PlumalexiusRestoration of the Middle Triassic-Eocene crinoid ("sea lily") PentacrinitesFossil of the Devonian-Cretaceous sponge PeronidellaA living Phoca earless sealA living Protula polychaete wormFossilized skull of the Eocene sea turtle Puppigerus. The shell belongs to another kind of turtle.Fossilized skeleton of the Late Cretaceous duck-billed dinosaur ParasaurolophusFossilized crest from the skull of the Late Cretaceous duck-billed dinosaur ParasaurolophusLife restoration of the Late Cretaceous duck-billed dinosaur Parasaurolophus being preyed upon by the tyrannosaur TeratophoneusRestoration of the Late Cretaceous dome-headed dinosaur PrenocephaleRestoration of the Late Triassic turtle ProganochelysA living Perognathus flavus, or silky pocket mouseA living Peromyscus boylii, or brush mouseA living Peromyscus eremicus, or cactus mouseFossil of the trilobite PaciphacopsRestoration of the Silurian-Devonian scorpion PalaeophonusFossil of the Silurian-Devonian scorpion PalaeophonusRestoration of the Silurian-Devonian scorpion PalaeophonusFossil of the Silurian-Early Devonian eurypterid ("sea scorpion") ParacarcinosomaRestoration of the Silurian-Early Devonian eurypterid ("sea scorpion")Fossil of the Ordovician trilobite ParaceraurusFossils of the Silurian-Middle Devonian eurypterid ("sea scorpion") ParahughmilleriaFossils of the Silurian-Middle Devonian eurypterid ("sea scorpion") ParahughmilleriaFossilized body of the Silurian-Middle Devonian eurypterid ("sea scorpion") ParahughmilleriaFossil of the Devonian trilobite Phacops ranaFossils of the Devonian trilobite Phacops ranaFossil in enrolled posture of the Devonian trilobite Phacops ranaIllustration of a fossil of the Cambrian arthropod PseudoniscusA living Pusa hispida, or ringed sealA living Pagrus sea breamA living Pagrus sea breamA modern Pagrus sea breamX-ray image of a modern Paragaleus weasel sharkRestoration of the Oligocene-Pleistocene false-toothed bird PelagornisA living Pelecanus, or pelicanShell of a Perotrochus slit sea snailFossilized vertebra of the Miocene-Pleistocene baleen whale PlesiocetusIllustration of a living Pomatomus saltatrix, or BluefishLiving Pontederia pickerel weedsA living Procellaria aequinoctialis, or white-chinned petrelA living Pseudorca crassidens, or false killer whaleA living Ardenna gravis (formerly Puffinus gravis), or great shearwaterFossilized skeleton of the Late Cretaceous dome-headed dinosaur PachycephalosaurusA living PhilodendronA living Platycarya treeFossil of the Devonian-Cretaceous sponge PeronidellaIllustration of a fossil of the Cambrian crustacean ProtocarisRestoration of the Oligocene-Miocene beaver PalaeocastorA living Parrotia, or Persian ironwoodRestoration of the Oligocene false saber-toothed cat Pogonodon in a treeFruit of a living Pyrus, or pear treeFossilized cranium of the Oligocene-Miocene tapir ProtapirusRestorative portrait of the Oligocene-Miocene tapir ProtapirusLife restoration of the Late Cretaceous mosasaur PlatecarpusA living Pinicola enucleator, or pine grosbeakRestoration of the Miocene-Pliocene red panda Pristinailurus, or Bristol's pandaA living Pleurostoma fungusShell of a Pleurotomella sea snailIllustration in multiple views of the shell of a Polygyra land snailRestorative models in multiple views of the Eocene brontothere Protitanotherium (figure 3)A living Pseudacris ocularis, or little grass frogA living Pseudacris streckeri, or Strecker's chorus frogA living Plestiodon obsoletus (formerly Eumeces obsoletus), or Great Plains skinkRestorative portrait of the Early Jurassic synapsid (mammal precursor) PachygenelusShell of a Pachymelania freshwater snailRestoration of the Late Triassic phytosaur PaleorhinusFossilized skull in multiple views of the Early Cretaceous armored dinosaur PawpawsaurusRestoration of the Early-Late Cretaceous ichthyosaur PlatypterygiusLife restoration of the Late Cretaceous mosasaur PlioplatecarpusIllustration of a fossilized partial jaw of the Late Cretaceous plesiosaur PolyptychodonFossilized skull of the Permian amphibian PantylusFossilized shell of the Permian ammonoid cephalopod ParaceltitesLife restoration of the Permian amphibian PelodosotisRestoration of the Cambrian shelled cephalopod PlectronocerasA preserved Pachycondyla antA living Phalaenoptilus nuttallii, or common poorwillFossilized skeleton of the Paleocene-Eocene arowana relative PhareodusA living Pipilo chlorurus, or green-tailed towheeRestoration of the Eocene horse Protorohippus. F. John (1902).Fossilized skeleton of the Paleocene-Eocene bird PseudocrypturusIllustration (figure 1) of a living Psilota hoverflyA living Pupilla land snailA living Petrochelidon pyrrhonota, or American cliff swallowLife restoration of the Late Cretaceous plesiosaur PlesiopleurodonFossilized shells of the Late Ordovician-Early Devonian nautiloid cephalopod PlagiostomocerasRestoration of the Carboniferous four-limbed animal ProterogyrinusLife restoration of the Permian reptile ProtorothyrisRestoration of the Early Triassic amphibian ParotosuchusIllustration of a living Pistia, or water lettuceFlowers of a living Polemonium, or Jacob's ladderFossilized skeleton of the Eocene creodont mammal ProviverraA living Parus, or titFruit of a living Phytolacca americana, or pokeberry
Fossilized skeleton of the Pliocene-Pleistocene elephant relative Stegomastodon
Life restoration of the Oligocene-Miocene camel Stenomylus
Fossil of the Middle Ordovician-Silurian trilobite SphaerexochusLife restoration of the mysterious Ediacaran animal SwartpuntiaFossilized shell of the Late Cretaceous ammonoid cephalopod ScalaritesBase of the trunk of a living Sequoia tree with a human to scaleDiagram illustrating the sizes of the Late Triassic ichthyosaurs Shonisaurus popularis (green) and S. sikanniensis (red) with an anachronistic human to scaleRestoration of three species of the Middle-Late Triassic ichthyosaur genus ShastasaurusRestorations of two species of the Early Cretaceous ammonoid cephalopod ShastocerasFossils of the Cambrian-modern worm burrow ichnogenus SkolithosLife restoration of the Late Cretaceous shark SqualicoraxLiving Sabal, or palmettosFossilized skeleton of the Eocene monitor lizard SaniwaFossilized teeth of the Neogene sperm whale ScaldicetusA living Scapanus latimanus, or broad-footed moleFossilized jaw and teeth of the Miocene horse ScaphohippusA living Sceloporus occidentalis, or western fence lizardA living Sciurus squirrelA living Scomberesox sauryIllustration of a living Scopelogadus ridgeheadA living Sebastes, the genus including the rockfishes and sea perchesA living Semicassis helmet sea snailFossilized skull of the Pliocene porpoise SemirostrumA living SequoiadendronRestoration of two species of the Oligocene oreodont mammal genus SespiaA living Sigmodon, or cotton ratA living Siliqua patula, or Pacific razor clamShell in multiple views of a Skenea californica, or California skeneaDiagram illustrating at scale various species of the Pleistocene-Holocene saber-toothed cat genus Smilodon; S. populator (green), S. fatalis (purple), and S. gracilis (orange) with a humanA living Otospermophilus beecheyi (formerly Spermophilus beecheyi), or California ground squirrelA living Callospermophilus lateralis (formerly Spermophilus lateralis), or golden-mantled ground squirrelA living Squalus, or spurdogA living Squatina californica, or Pacific angelsharkFossilized skeleton of the Miocene weasel SthenictisFossilized skeleton of the fossil pronghorn StockocerosShell in two views of Lobatus galeatus (formerly Strombus galeatus), or Eastern Pacific giant conch. Louis Charles Kiener (1843).Fossilized skeleton of the Eocene-Oligocene tortoise StylemysRestoration of the Eocene-Oligocene cow-sized rhinoceros Subhyracodon. Charles R. Knight (1890s).A living Sylvilagus audubonii, or desert cottontailA living Syngnathus pipefishA living Synthliboramphus antiquus, or ancient murreletA living Synthliboramphus hypoleucus, or Guadalupe murreletFossilized skeleton of the Permian primitive four-limbed animal SeymouriaA living Saperda flat-faced longhorn beetleA living Sceloporus undulatus, or eastern fence lizardAdult, larva, and pupa of a living Scolytus bark beetleFossilized branch fragment from a Sequoia affinisRestorative model of the Eocene horse SifrhippusRestoration of the Paleocene mesonychid mammal Sinonyx (top)A living Sitona weevilFossilized skeleton of the Eocene primate SmilodectesA living Spea bombifrons, or plains spadefoot toadA living Urocitellus richardsonii (Spermophilus richardsonii), or Richardson's ground squirrelRestoration of the Eocene brontothere mammal SphenocoelusA living Spizella breweri, or Brewer's sparrowA living Staphylea, or bladdernutA living Stenolophus ground beetleRipe fruit capsule and seeds of a living Sterculia, or tropical chestnutLiving Stipa, or feather grassLife restoration of the Eocene taeniodont mammal StylinodonA living Sylvilagus, or cottontail rabbitFossilized skull of the Miocene toothed whale SchizodelphisRestoration of the Oligocene-Miocene shark-toothed dolphin SqualodonLiving Sabal palmettoA living SardinellaDevelopmental series of shells of Scaphella junonia, or the Juno's volute sea snailA living Scaphiopus holbrookii, or eastern spadefoot toadA living Sciurus carolinensis, or eastern gray squirrelShell in multiple views of a Semicassis granulata, or Scotch bonnet sea snailLiving Serenoa, or saw palmettoLiving Siderastrea siderea, or massive starlet coralA living Sigmodon hispidus, or hispid cotton ratA living Simnia false cowrieA living Siren lacertina, or greater sirenA living Sistrurus miliarius rattlesnakeShell of a Solariella top sea snailA living Somateria spectabilis, or king eiderA living Sorex longirostris, or southeastern shrewA living Sphyraena barracuda, or great barracudaA living Spizaetus, or typical hawk-eagleShell of a Spondylus americanus, or Atlantic thorny oysterA living Stellifer, or stardrumA living Sternotherus, or musk turtleShell of a Stramonita murex sea snailShell of a Strioterebrum augur sea snailShell of a Strobilops land snailShell of a Strombina dove sea snailA living Strombus alatus, or Florida fighting conch Fossilized shell in multiple views of a Strombus alatus, or Florida fighting conchA living Sturnella magna, or eastern meadowlarkShell of a Subcancilla sea snailA living Sylvilagus palustris, or marsh rabbitIllustration of a living Synaptomys, or bog lemmingA living Synodus foetens, or inshore lizardfishA living Squatina, or angel sharkClose-up portrait of a Siren intermedia, or lesser sirenA living Sphyrna tiburo, or bonnethead sharkA living Synodus lizardfishFossil of the Cambrian priapulid worm SelkirkiaFossil of the Carboniferous colonial rugose coral SiphonodendronFossilized skeleton of the Early Triassic-Middle Jurassic bony fish SaurichthysFossilized skeleton of the Early Triassic-Middle Jurassic bony fish SaurichthysRestoration of the Early Triassic-Middle Jurassic bony fish Saurichthys preying upon a pterosaurFossilized shell of the Middle Jurassic ammonoid cephalopod StephanocerasReconstruction of a fossilized skull and restorative portrait of the Miocene-Pliocene red panda relative SimocyonRestorative portrait of the Miocene-Pliocene red panda relative SimocyonFossilized leaves and branches of the Devonian-Triassic horsetail relative SphenophyllumDiagram illustrating the Late Devonian-Carboniferous Chimaera relative Stethacanthus with an anachronistic human to scaleLife restoration of the Late Devonian-Carboniferous Chimaera relative StethacanthusLife restoration of the Carboniferous Chimaera relative SymmoriumFossil of the Carboniferous Chimaera relative SymmoriumFossilized calyx of the Carboniferous crinoid ("sea lily") ScytalocrinusRestoration of the Carboniferous reptile SpinoaequalisIllustration of a fossilized cranium of the Late Cretaceous armored dinosaur SilvisaurusAnimated Restoration of the Late Cretaceous plesiosaur StyxosaurusA living Scaphiopus, or North American spadefoot toadFossilized partial cranium of the Soergelia mayfieldi, or Soergel's oxA living Sorex palustris, or American water shrewA living Ictidomys tridecemlineatus (formerly Spermophilus tridecemlineatus), or thirteen-lined ground squirrelShells in differing orientations of Sphaerium freshwater clamsIllustration of a living Novisuccinea ovalis (formerly Succinea ovalis), or amber oval land snailA living Sylvilagus floridanus, or eastern cottontailShell of a Scaphella volute sea snailA living Sciaena umbra, or brown meagreFossils of the Ordovician-Silurian brittle star StenasterFossilized teeth of the Cretaceous-Eocene shark SerratolamnaIllustration of living Schizoporella unicornis bryozoans ("moss animals")A living Sorex cinereus, or cinereus shrewA living Squatina, or angelsharkIllustration of a living Squilla empusa mantis shrimpA living Synaptomys cooperi, or southern bog lemmingFossils of the Cambrian mollusc ScenellaRestoration of the Early Cretaceous armored dinosaurs SauropeltaFossilized cranium in multiple views of the Late Cretaceous armored dinosaur ScolosaurusFossils of the dinosaur egg oogenus SpheroolithusRestoration of the Late Cretaceous horned dinosaur SpiclypeusFossilized skull of the Late Cretaceous dome-headed dinosaur StegocerasFossilized skeleton of the Late Jurassic long-necked dinosaur SuuwasseaFossilized bones of the Paleocene-Eocene choristoderan reptile SimoedosaurusFossilized partial skulls of the rodent Oligocene-Miocene SteneofiberRestoration of the Miocene deer relative Subdromomeryx. Robert Bruce Horsfall (1913). A living Scalopus aquaticus, or eastern moleIllustration of fossilized shells of the mysterious Cambrian organism SalterellaFossilized shell of the Early Jurassic ammonoid cephalopod SchlotheimiaFossilized skull of the Late Triassic giant ichthyosaur ShonisaurusDiagram illustrating Shonisaurus (green) and Shastasaurus sikanniensis (red) with an anachronistic human to scaleRestoration of the Late Triassic giant ichthyosaur ShonisaurusCloseup view of an amber-entombed specimen of the Late Cretaceous ant SphecomyrmaAmber-entombed specimen of the Late Cretaceous ant SphecomyrmaFlower of a living StewartiaRestoration of the Late Cretaceous duck-billed dinosaur SaurolophusRestoration of the Late Triassic distant crocodilian relative ShuvosaurusLife restoration of the Late Triassic aetosaur StagonolepisRestoration of the Late Cretaceous dome-headed dinosaur StegocerasRestoration of the Late Cretaceous ostrich dinosaur StruthiomimusFossilized skeleton of the Eocene-Oligocene creodont mammal SinopaFossilized shell of the Cambrian-Late Ordovician mollusc ScenellaFossils of the Cambrian trilobite SerrodiscusFossil of the Silurian eurypterid ("sea scorpion") SlimoniaRestoration of the Silurian eurypterid ("sea scorpion") SlimoniaRestoration of the Silurian eurypterid ("sea scorpion") SlimoniaFossil of the burrow ichnogenus SpirorhapheRestoration of the Devonian eurypterid ("sea scorpion") StylonurusLiving Sanguisorba canadensis, or Canadian burnetIllustration of a living Sarda sarda, or Atlantic bonitoA living Scoliodon, or spadenose sharkA living Seriola, or amberjackA living Somateria mollissima, or common eiderA modern Sphoeroides pufferfishA living Sphyrna lewini, or scalloped hammerheadA living Stenella, or oceanic dolphinIllustration of a living Stenotomus chrysops, or scupIllustration of a living Stercorarius longicaudus, or long-tailed jaeger. Johann Friedrich NaumannA living Thalasseus maximus, or royal ternA living Symphurus tonguefishRestoration of the Permian reptile relative SeymouriaFossilized skeletons of the Permian reptile relative SeymouriaRestoration of a pair of the Permian reptile relative SeymouriaRestoration of the Late Jurassic theropod dinosaur SaurophaganaxDiagram illustrating the size of the Early Cretaceous long-necked dinosaur Sauroposeidon, with an anachronistic human to scaleFossilized partial skull in multiple views of the Middle-Late Triassic ichthyosaur ShastasaurusFossilized shell of the Early Cretaceous ammonoid cephalopod SpitidiscusFossilized fin of the Devonian lobe-finned fish SauripterusFossil of the Early Devonian primitive vascular land plant SciadophytonRestorative model of the Cambrian arthropod SidneyiaFossils of the Cambrian arthropod SidneyiaShell of a living Saxidomus gigantea, or butter clamA living Somatochlora dragonflyA living Stercorarius, or skuaFossilized tooth of the Late Cretaceous shark SqualicoraxFossil of the Cambrian-Ordovician trilobite SaukiellaFossilized calyx and partial stem of the Silurian crinoid ("sea lily") SagenocrinitesFossils of the Cambrian-modern worm burrow ichnogenus SkolithosShell of a Siphonaria false limpet sea snailA living Sylvilagus aquaticus, or swamp rabbitShell of a Sassia triton sea snailA living Siren salamanderA living Xerospermophilus spilosoma, or spotted ground squirrelShells in differing orientations of Stagnicola freshwater snailsDiagram illustrating the Early Cretaceous long-necked dinosaur Sauroposeidon with anachronistic humans to scaleFossilized snout of the Late Cretaceous ray relative SclerorhynchusA living Squalus, or spurdogRestorative portrait of the Permian synapsid (mammal precursor) SecodontosaurusLife restoration of the Late Devonian-Permian SphenacanthusRestorative portrait of the Permian synapsid (mammal precursor) SteppesaurusDiagram illustrating the maxilla of the Permian synapsid (mammal precursor) Steppesaurus compared to a cranium of SphenacodonFossils of the seafloor animal trail ichnogenus ScoliciaLife restoration of the Carboniferous-Permian synapsid (mammal precursor) SphenacodonFoliage of a living Sassafras treeFoliage of a living SchoepfiaA living Sialia, or bluebirdA living Sloanea treeFoliage and fruit of a living SmilaxA living Sturnella neglecta, or western meadowlarkFlowers and foliage of a living Styrax, also known as storax or snowbelRestoration of the Miocene protoceratid mammal SyndyocerasA living Seiurus aurocapilla, or ovenbirdA living Sialia sialis, or eastern bluebirdA living Squalus , or spurdogA living Sturnella meadowlarkA living Sylvilagus transitionalis, or New England cottontailA living Setophaga coronata, or yellow-rumped warblerKnown material diagram of the Early Jurassic primitive long-necked dinosaur SeitaadLife restoration of the Late Cretaceous theropod dinosaur SiatsA living Spatula discors (formerly Anas discors), or blue-winged teal
Life restoration of the Carboniferous-Triassic freshwater shark Triodus
Fossilized skeleton of the Early Cretaceous Iguanodon relative Tenontosaurus
Restoration of the Early Cretaceous Iguanodon relative Tenontosaurus
Fossilized skeleton of the Late Triassic reptile Trilophosaurus.
Restoration of the Late Triassic reptile Trilophosaurus with an anachronistic human to scale
Restoration of a pair of the Late Triassic aetosaur Typothorax
Restoration of the Pleictocene pronghorn Tetrameryx
Fossils of the bore-hole ichnogenus TrypanitesIllustration of a fossil of the Cambrian trilobite TrinodusA living Terebralia horn sea snailReconstructed skull in side (above) and top view of the Late Triassic thalattosaur Thalattosaurus. The frontmost portion of the snout is portrayed erroneously as straight; it actually had a pronounced downward curveDiagram of the anatomy of a Trigonia marine bivalveFossilized shell in multiple views of the Early-Late Cretaceous sea snail TrochactaeonFossilized shell of the Late Cretaceous ammonoid cephalopod TurrilitesIllustration in multiple views of fossilized shells belonging to the Jurassic-modern tower shell sea snail TurritellaFlower of a living Tabernaemontana, or milkwoodRestoration of the Eocene carnivoran relative TapocyonA living Tayassu pecari, or white-lipped peccary, with offspringRestoration of the Pleistocene bird of prey TeratornisFossilized shell in two views of the Late Devonian-modern brachiopod TerebratulaRestoration of the Miocene fur seal ThalassoleonClose-up portrait of a living Thomomys bottae, or Botta's pocket gopher emerging from its burrowA school of living Thunnus, or tunasFossilized skull of the Miocene oreodont mammal TicholeptusFossilized skeleton of the Miocene-Pleistocene camel TitanotylopusFossilized skull of the Miocene bone-crushing dog TomarctusFoliage of living ToxicodendronA living Toxopneustes roseus, or rose flower urchin. The object on top of the animal is a piece of coral rubble.A living Tremarctos, or spectacled bearA living Triakis houndsharkA living Triplofusus spindle sea snailShell of a Tucetona bittersweet clamShell of a Turbonilla laminata pyram shell sea snailShell of a Turcica sea snailShell of a Turritriton gibbosus triton sea snailA living Tursiops, or bottlenose dolphinFossil of the Silurian-Carboniferous crinoid ("sea lily") Taxocrinus (right)Close-up portrait of a living Tabanus horseflyA living Tachycineta bicolor, or tree swallowA living Tamiasciurus hudsonicus, or American red squirrelA living Tanysphyrus lemnae weevilFossilized mandible of the Eocene primate TeilhardinaA living Tenthredo sawflyA living Tetragnatha spiderLiving Batagur turtlesA living Thamnophis elegans, or western terrestrial garter snakeA living Thanasimus checkered beetle with preyA living Themira black scavenger flyA living Thomisus crab spiderA living Thomomys, or smooth-toothed pocket gopherA living Thuja treeA living member of Tilia, the genus including the lindens and basswoodsA living Tipula crane flyLife restoration of the Paleocene pantodont mammal TitanoidesFoliage of a living Torreya, or nutmeg yewA living Tortrix mothFruits and foliage from a modern TrichiliaRestoration of the Eocene creodont mammal TritemnodonA living Tropisternus water scavenger beetleA living Trox hide beetleLiving Typha, or cattailsA living Tachybaptus dominicus, or least grebeA living Tamias chipmunkShell of a Tectonatica pusilla moon sea snailShell in multiple views of a Tegula fasciata, or Smooth Atlantic TegulaFossilized skeleton of the Pleistocene bird of prey TeratornisShell in multiple views of a Terebra dislocata, or eastern auger sea snailA living Terrapene, or box turtleA living Terrapene carolina, or common box turtleLiving Thalassia testudinum, or turtlegrassIllustration of living Thalassodendron sea grassFossilized skeleton of the Miocene-Pliocene ground sloth ThinobadistesFossilized skeleton of the Pliocene-Pleistocene terror bird TitanisLife restoration of the Pliocene-Pleistocene terror bird TitanisA living Toxostoma rufum, or brown thrasherA living Trachemys scripta, or pond sliderShell of a Trachycardium egmontianum, or the Florida prickly cockleExterior and interior of the shell of a Trachycardium isocardia, or West Indian prickly cockleA living Trichechus manatus, or West Indian manateeShell of a Tricolia pheasant shell sea snailA living Tringa melanoleuca, or greater yellowlegsA living Tringa solitaria, or solitary sandpiperA living Triplofusus papillosus, or Florida horse conchA living Troglodytes aedon, or house wrenClose-up portrait of a living Tropidophis, or West Indian wood snakeShell of a Turbo castanea, or chestnut turban sea snailShell of a Turbonilla hemphilli pyram sea snailShell in multiple views of a Tutufa frog shell sea snailClose-up portrait of a living Typhlops blind snakeFossil of the Cambrian trilobite TricrepicephalusFossilized skull of the Late Cretaceous-Paleocene gavial relative ThoracosaurusFossil of the Cambrian trilobite ThoracocareRestoration of the Cretaceous tree-like fern TempskyaPart and counterpart fossils of the mysterious Carboniferous life-form Tullimonstrum, or the Tully monsterRestoration of the mysterious Carboniferous life-form Tullimonstrum, or the Tully monsterFossil of the mysterious Carboniferous life-form Tullimonstrum, or the Tully monsterA living Thamnophis radix, or plains garter snakeA living Tympanuchus, or prairie chickenStand of living Taxodium cypressesA living Tectonatica moon sea snailA living Tamias striatus, or eastern chipmunkFossilized skeleton of the Paleocene-Eocene sea turtle TasbackaFossilized skeleton of the Oligocene-Miocene gavial relative ThecachampsaFossil of the mysterious Cambrian animal TorellellaIllustration of a fossilized shell in multiple views of the Silurian monoplacophoran mollusc Tryblidium reticulatum. Head region is to the left.Fossilized skull of the Late Cretaceous crocodilian relative TerminonarisRestoration of the Late Cretaceous herbivorous dinosaur ThescelosaurusFossilized teeth of the Late Cretaceous duck-billed dinosaur TrachodonFossilized skeleton of the Late Cretaceous horned dinosaur TriceratopsIllustration of fossilized teeth of the Late Cretaceous TroodonRestoration of the Paleocene multituberculate mammal TaeniolabisA living Thomomys talpoides, or northern pocket gopherRestoration of the Paleocene pantodonts mammal TitanoidesSeeds of a modern Trapa, or water caltropLiving Terrapene ornata, or western box turtlesA living Thamnophis radix, or plains garter snakeFossilized shell of the Cambrian arthropod TuzoiaFossilized shell of the Cambrian arthropod TuzoiaRestoration of the Middle Triassic ichthyosaur ThalattoarchonFossil of the Triassic-Eocene stony coral ThamnasteriaA living Trichechus, or manateeRestoration of the Late Triassic theropod dinosaur TawaFossilized skeleton of the Late Cretaceous horned dinosaur TitanoceratopsRestoration of the Paleocene multituberculate mammal TaeniolabisFossilized jaw of the Eocene brontothere mammal TelmatheriumFossilized partial skull of the Paleocene mesonychid mammal TriisodonExterior and interior of the shell of a Tagelus marine bivalveDiagram of the branches of the Middle-Late Devonian vascular plant TetraxylopterisFossilized shell of the Middle-Late Devonian nautiloid cephalopod TrochocerasIllustration of a living Thunnus thynnus, or Atlantic bluefin tunaA living Triaenodon obesus, or whitetip reef sharkFossilized skull of the Permian amphibian TrimerorhachisFossilized skull of the Permian amphibian TrimerorhachisFossilized skull of the Permian amphibian TrimerorhachisIllustration of a fossilized skull in multiple views of the Permian amphibian TrimerorhachisEdward Drinker Cope.Foliage and cones of a living Tetraclinis, or arar treeShell of a Thesbia sea snailShell of a Trichotropis cap sea snailA living Tympanuchus pallidicinctus, or lesser prairie chickenA living Tursiops truncatus, or common bottlenose dolphinShell of a Thylacodes worm shell sea snailA living Tropidoclonion, or lined snakeA living Truncilla truncata freshwater mussel, or DeertoeRestoration of the Late Cretaceous plesiosaur TrinacromerumFossil of the Carboniferous crustacean TesnusocarisFossilized skull in multiple views of the Permian synapsid (mammal precursor) TetraceratopsRestorative portrait of the Permian synapsid (mammal precursor) TetraceratopsRestoration of the Permian synapsid (mammal precursor) TetraceratopsRestoration of the Carboniferous-Permian trilobite TriproetusRestoration of the Permian reptile relative TseajaiaFossilized partial cranium of the Eocene brontothere mammal TelmatheriumA modern uprooted Thelypteris, or maiden fernFossil of the Eocene giant ant Titanomyrma with a preserved rufous hummingbird for scaleIllustration of a living Tritoma pleasing fungus beetleLeaf and flowers of a living Triumfetta, or burbarkA living Trypodendron ambrosia beetleA living Tympanuchus phasianellus, or sharp-tailed grouseIllustration of a living Thyrsopteris tree fernRestoration of the Late Cretaceous horned dinosaur TorosaurusFossilized teeth of the Late Cretaceous theropod dinosaur TroodonRestoration of the Silurian arthropod ThylacaresA living Triodopsis tridentata land snail, or northern threetoothKnown material diagram of the Late Cretaceous troodontid TalosRestoration of the Late Jurassic theropod dinosaur TanycolagreusKnown material diagram of the Late Cretaceous tyrannosaur TeratophoneusFossilized skeleton of the Late Jurassic megalosaur TorvosaurusFossil of the Late Cretaceous tyrannosaur footprint ichnogenus TyrannosauripusFossils of the bore-hole ichnogenus TrypanitesRestoration of the Late Jurassic megalosaur Torvosaurus
A living Urocyon cinereoargenteus, or gray foxA living Uca, or fiddler crabRestoration of the Eocene mammal UintatheriumA pair of living Uria aalge, or common murreA living Uta stansburiana, or common side-blotched lizardA living Uca pugnax, or Atlantic marsh fiddler crabFossils of the Late Cretaceous crinoid ("sea lily") UintacrinusFossilized calyx ad partial stem of the Carboniferous crinoid ("sea lily") UlrichicrinusA living Umbrina croakerLiving Uria, also known as murres of guillemotsA modern Urophycis hakeA living Ursus arctos, or brown bearLife restoration of the Carboniferous amphibian UtaherpetonFossilized jaws of the Late Devonian lungfish UranolophusRestoration of the Late Cretaceous horned dinosaur UtahceratopsDiagram illustrating the Early Cretaceous dromaeosaurid ("raptor") Utahraptor with an anachronistic human to scaleFossilized skeleton of the Late Jurassic Iguanodon relative Uteodon
A living Vasum, or vase sea snailBranches and foliage of a living Vauquelinia, or rosewoodFossilized shell of the Paleocene-Miocene nerite sea snail VelatesShell of a Velutina velutina or velvet shell sea snailA living VireoA living Voluta sea snailFossilized skeleton of the Eocene mammal VulpavusFossilized shell in multiple views of the Pleistocene shaggy vase sea snail Hystrivasum horridum (formerly Vasum horridum)Shell in multiple views of a Vasum muricatum, or Caribbean vase sea snailA living Oreothlypis celata (formerly Vermivora celata), or orange-crowned warblerShell of a Vertigo milium, or blade vertigo land snailFlowers of a living Viburnum dentatum, or southern arrowwoodA living Vireo griseus, or white-eyed vireoFruit and foliage of living Vitis rotundifolia, or muscadine grape vinesShell of a Viviparus georgianus, or banded mystery snailShell in multiple views of a Vokesimurex rubidus, or rose murex sea snailA living Vespertilio batShell in multiple views of a Volema crown conchRestorations of the Late Cretaceous marine bivalve VolviceramusShell of a Viviparus freshwater snailFossilized skeleton of the Permian synapsid (mammal precursor) VaranopsRestoration of the Permian synapsid (mammal precursor) VaranopsRestoration of the Permian synapsid (mammal precursor) VaranopsA living Vallonia land snailOpening of the shell of a Vertigo ovata land snail, or ovate vertigoFossilized skeleton of the Permian synapsid (mammal precursor) VaranosaurusFossil of the Cambrian-Silurian sponge VauxiaFossilized skeleton of the Eocene bony fish VoltacongerA living Valvata freshwater snail
Fossil of the Cambrian trilobite WanneriaFlowers of a living WeinmanniaFossils (figures 1-5) of the Silurian eurypterid ("sea scorpion") WaeringopterusFossilized head of the Silurian eurypterid ("sea scorpion") WaeringopterusLiving Woodwardia fernsFossilized roots of the Middle Devonian tree WattiezaFossilized skeleton of the Paleocene Alligator relative Wannaganosuchus
Fossilized partial skull of the Early Cretaceous crocodilian Wannchampsus with a modern Crocodylus porosus skull in the background for comparisonFossilized partial skulls of the Early Cretaceous crocodilian WannchampsusRestoration of the Cambrian arthropod WaptiaRestoration of the Cambrian possible mollusc WiwaxiaFossils of the Middle Jurassic-Early Cretaceous fern Weichselia
Fossilized shells of the ammonoid cephalopod XenodiscusFossilized shell of the Late Cretaceous-modern carrier shell sea snail XenophoraA living Xantholinus rove beetleA living Xestobium beetleA living Xylocopa, or carpenter beeShell of a Xenophora conchyliophora carrier shell sea snailFossilized skeleton of the Pleistocene saber-toothed cat XenosmilusFossilized skeleton of the Miocene whale XiphiacetusA living Xiphias, or swordfishReconstructed skeleton of the Late Devonian-Triassic shark XenacanthusA living Xanthocephalus xanthocephalus, or yellow-headed blackbirdRestoration of the Late Devonian–Triassic freshwater shark XenacanthusA living Xema sabini, or Sabine's gullFossilized skull of the Pliocene-Pleistocene wolf XenocyonFossilized skeleton of the Late Devonian–Triassic freshwater shark Xenacanthus
Shell of a Yoldia limatula, or file yoldiaLife restoration of the Miocene bear dog YsengriniaRestoration of the probable Cambrian mollusc YochelcionellaLife restoration of the Early Cretaceous dromaeosaurid ("raptor") Yurgovuchia
A living Zalophus californianus, or California sea lionFossil of the Early Triassic-Eocene cycad-like frond ZamitesRestoration of the Miocene snake mackerel relative EuzaphlegesKnown material diagram depicting the Miocene-Pleistocene mastodon relative Zygolophodon with a human to scaleA living Zamia cycadA living Zonotrichia leucophrys, or white-crowned sparrowA living Zapus hudsonius, or meadow jumping mouseLeaf of a living Zelkova treeMicrograph with magnified inset of a fossilized tooth of the Late Cretaceous theropod dinosaur ZapsalisFossilized cranium of the Miocene-Pleistocene mastodon relative ZygolophodonA living Zygaena mothRestoration of the Late Cretaceous armored dinosaur ZiapeltaRestoration of the Late Cretaceous primitive horned dinosaur ZuniceratopsA living Zenaida doveFossil of the polychaete worm feeding trace ichnogenus ZoophycosIllustration of a living Ziphius cavirostris, or Cuvier's beaked whaleRestoration of the Permian amphibian ZatrachysA living Zapus jumping mouseLiving Zonitoides arboreus land snailsIllustration of a living Ziziphus with insets detailing the anatomy of its flower, fruit, and seedsA living Zonotrichia albicollis, or white-throated sparrow
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