# List of the Mesozoic life of Colorado

This list of the Mesozoic life of Colorado contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Colorado and are between 252.17 and 66 million years of age.

## A

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* †Acanthichnus – tentative report
* Acila
** †Acila chicotana
* Acmaea
** †Acmaea genettae – type locality for species
* †Adocus
* †Albanerpeton
** †Albanerpeton nexuosus
* †Albertosaurus – tentative report
* †Allantodiopsis
** †Allantodiopsis erosa
** †Allantodiopsis JC018 – informal
* Life restoration of the Late Jurassic theropod dinosaur Allosaurus †Allosaurus – type locality for genus
** †Allosaurus fragilis – type locality for species
** †Allosaurus lucasi – type locality for species
* †Amblotherium – type locality for genus
** †Amblotherium gracilis
* Amia
* †Amphicoelias – type locality for genus
** †Amphicoelias altus – type locality for species
* Fossilized skull of the Late Jurassic crocodile relative Amphicotylus †Amphicotylus
** †Amphicotylus lucasii – type locality for species
* †Amplovalvata
** †Amplovalvata scabrida
* †Anaklinoceras
** †Anaklinoceras minutum – type locality for species
** †Anaklinoceras reflexum
* †Anisoceras
** †Anisoceras plicatilis
* †Anisomyon
** †Anisomyon centrale
* †Anomia
** †Anomia subquadrata
** †Anomia tellinoides
* Fossil (right) of the Early Jurassic dinosaur footprint ichnogenus Anomoepus †Anomoepus – tentative report
* †Apateodus
* †Apatopus
* †Apatosaurus – type locality for genus
** †Apatosaurus ajax – type locality for species
** †Apatosaurus laticollis – type locality for species. Junior synonym of A. louisae.
** †Apatosaurus louisae
* †Arcellites
** †Arcellites disciformis
* †Archaeolamna
** †Archaeolamna kopingensis
* †Arenicolites
* Aspideretes
** †Aspideretes vagans – type locality for species
* †Aspideretoides
* Astarte
* †Atlantosaurus
** †Atlantosaurus immanis – type locality for species
* †Axonoceras
** †Axonoceras compressum

## B

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* †Baculites
** †Baculites aquilaensis
** †Baculites asper
** †Baculites clinolobatus – type locality for species
** †Baculites codyensis
** †Baculites compressus
** †Baculites cuneatus
** †Baculites grandis
** †Baculites haresi
** †Baculites mclearni
** †Baculites meeki – type locality for species
** †Baculites reesidei
* Restoration of the Late Jurassic sauropod dinosaur Barosaurus rearing to defend itself against a pair of the theropod Allosaurus †Barosaurus
* †Basilemys
** †Basilemys sinuosa – or unidentified comparable form
* †Behuninia
** †Behuninia provoensis
* †Bellifusus
* †Bison
** †Bison alticornis – type locality for species
* †Borealosuchus
** †Borealosuchus sternbergii
* †Brachauchenius – or unidentified comparable form
* †Brachiosaurus – type locality for genus
** †Brachiosaurus altithorax – type locality for species
* †Brachychampsa
** †Brachychampsa montana
* †Brachychirotherium
* †Brachyphyllum
** †Brachyphyllum rechtenii – type locality for species
* Life restoration of a herd of the Late Jurassic sauropod dinosaur Brontosaurus †Brontosaurus
** †Brontosaurus excelsus
** †Brontosaurus yahnahpin

## C

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* †Calycoceras
** †Calycoceras canitaurinum
** †Calycoceras naviculare
* Life restoration of a herd of the Late Jurassic sauropod dinosaur Camarasaurus †Camarasaurus – type locality for genus
** †Camarasaurus agilis – type locality for species
** †Camarasaurus grandis
** †Camarasaurus lewisi
** †Camarasaurus supremus – type locality for species
* †Camptosaurus – type locality for genus
** †Camptosaurus dispar – type locality for species
* Carcharias
** †Carcharias amonensis
** †Carcharias saskatchewanensis
** †Carcharias tenuiplicatus
* †Caririchnium
** †Caririchnium leonardii – type locality for species
** †Caririchnium leonaridii
* †Cataceramus
** †Cataceramus gladbeckensis
* †Cedrobaena
** †Cedrobaena brinkman
* †Ceratodus – type locality for genus
** †Ceratodus felchi – type locality for species
** †Ceratodus guentheri – type locality for species
* Restoration of the Late Jurassic ceratosaur Ceratosaurus †Ceratosaurus – type locality for genus
** †Ceratosaurus nasicornis – type locality for species
* Cerithiopsis
* †Champsosaurus
* Chara
* †Chelonipus
* †Chinlea
** †Chinlea sorenseni
* †Chinlestegophis – type locality for genus
** †Chinlestegophis jenkinsi – type locality for species
* †Chirotherium
** †Chirotherium lulli
* †Cimolichthys
** †Cimolichthys nepaholica
* †Cimolodon – or unidentified comparable form
* Life restoration of the face of the Late Cretaceous multituberculate mammal Cimolomys †Cimolomys
* †Cionichthys
** †Cionichthys dunklei
* †Cionodon – type locality for genus
** †Cionodon arctatus – type locality for species
* †Cirroceras
** †Cirroceras conradi
* †Cladoceramus
** †Cladoceramus undulatoplicatus
* †Clidastes
* †Clioscaphites
** †Clioscaphites choteauensis
** †Clioscaphites saxitonianus
** †Clioscaphites vermiformis
* †Coahuilites
** †Coahuilites sheltoni
* †Cochlichnus
* †Codellaster – type locality for genus
** †Codellaster keepersae – type locality for species
* †Coelophysis – tentative report
* Diagram illustrating the known fossil material of the Late Jurassic theropod dinosaur Coelurus †Coelurus
** †Coelurus fragilis
* †Compsemys
** †Compsemys victa
* †Coniasaurus
** †Coniasaurus crassidens
* Corbula
* †Corydalites – type locality for genus
** †Corydalites fecundum – type locality for species
* Crassatella
** †Crassatella franzeseii
* †Cremnoceramus
** †Cremnoceramus deformis
* †Crenella
* †Creonella
** †Creonella triplicata
* †Cretodus
** †Cretodus semiplicatus
* †Cretolamna
** †Cretolamna appendiculata
* †Cretomanta
** †Cretomanta canadensis
* Restoration of the Late Cretaceous shark Cretoxyrhina, or the Ginsu shark †Cretoxyrhina
** †Cretoxyrhina mantelli
* Cucullaea
** †Cucullaea nebrascensis
* Cuspidaria
** †Cuspidaria ventricosa
* †Czekanowskia
** †Czekanowskia turneri – tentative report

## D

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* †Diablophis
** †Diablophis gilmorei – type locality for species
* †Didymoceras
** †Didymoceras aurarium – type locality for species
** †Didymoceras cheyennense
** †Didymoceras draconis
** †Didymoceras stevensoni
* †Dinehichnus
** †Dinehichnus socialis
* †Dinochelys
** †Dinochelys whitei
* Diagram illustrating the Late Jurassic sauropod dinosaurs Diplodocus carnegii (green) and D. hallorum (orange) with an anachronistic human to scale. †Diplodocus – type locality for genus
** †Diplodocus lacustris – type locality for species
** †Diplodocus longus – type locality for species
* Diplodonta
** †Diplodonta davisi
* †Diplosaurus
** †Diplosaurus felix – type locality for species
* Discinisca
* †Discoscaphites
** †Discoscaphites conradi
* †Docodon
** †Docodon apoxys – type locality for species
* †Dorsetisaurus
* Fossilized skull of the Late Jurassic-Early Cretaceous turtle Dorsetochelys †Dorsetochelys
** †Dorsetochelys buzzops – type locality for species
* †Drepanocheilus
** †Drepanocheilus evansi
** †Drepanocheilus nebrascensis
** †Drepanocheilus obesus
* †Dryophyllum
** †Dryophyllum tennesseensis
* †Dryosaurus
** †Dryosaurus altus

## E

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* †Edmontonia
* Skeletal reconstruction and restored soft tissue of the Late Cretaceous duck-billed dinosaur Edmontosaurus regalis with an anachronistic human to scale †Edmontosaurus
** †Edmontosaurus regalis – type locality for species
* Eilenodon – type locality for genus
** †Eilenodon robustus – type locality for species
* †Elopopsis
* †Enchodus
** †Enchodus gladiolus – or unidentified comparable form
** †Enchodus shumardi – or unidentified comparable form
* †Entolium
* †Eoacteon
** †Eoacteon sublinearis
* †Eomunidopsis
** †Eomunidopsis cobbani – type locality for species
* †Eosauropus
** †Eosauropus cimarronensis
** †Eosauropus cimmaronensis
* A living Equisetum, or horsetail †Equisetum
** †Equisetum burchardtii – or unidentified comparable form
* †Etea
** †Etea peasei
* †Eubrontes
** †Eubrontes giganteus
* †Eucalycoceras
** †Eucalycoceras pentagonum
* †Euomphaloceras
** †Euomphaloceras septemseriatum
* †Eutrephoceras
** †Eutrephoceras dekayi
* †Eutretauranosuchus – type locality for genus
** †Eutretauranosuchus delfsi – type locality for species
* †Exiteloceras
** †Exiteloceras jenneyi
* †Exogyra
** †Exogyra boveyensis – or unidentified related form

## F

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* Fossilized shell of the Late Cretaceous ammonoid cephalopod Fagesia †Fagesia
* Ficus
** †Ficus planicostata
* †Forresteria
** †Forresteria hobsoni – type locality for species
* †Fruitachampsa – type locality for genus
** †Fruitachampsa callisoni – type locality for species
* †Fruitadens – type locality for genus
** †Fruitadens haagarorum – type locality for species
* †Fruitafossor – type locality for genus
** †Fruitafossor windscheffeli – type locality for species

## G

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* Fossilized skull of the Late Jurassic sauropod dinosaur Galeamopus †Galeamopus
** †Galeamopus pabsti
* †Glirodon
** †Glirodon grandis
* †Glyptops
** †Glyptops plicatulus – type locality for species
* †Goniopholis
** †Goniopholis felchi – type locality for species
* †Grallator
** †Grallator cursorius
** †Grallator tenuis
* †Gryphaeostrea
* †Gwyneddichnium
* †Gypsonictops
* †Gyroides

## H

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* Restoration of the Late Jurassic crocodile relative Hallopus †Hallopus
** †Hallopus victor – type locality for species
* †Haplocanthosaurus – type locality for genus
** †Haplocanthosaurus delfsi – type locality for species
** †Haplocanthosaurus priscus – type locality for species
* †Harduinia
** †Harduinia stantoni
** †Harduinia taylori
* †Haresiceras
** †Haresiceras placentiforme
* †Helopanoplia
** †Helopanoplia distincta – or unidentified comparable form
* †Hemicalypterus
* †Hermanophyton
* Fossilized shell of the Late Cretaceous ammonoid cephalopod Herrickiceras †Herrickiceras
** †Herrickiceras costatus
* †Holaster
** †Holaster feralis – type locality for species
* †Homolopsis
* †Hoploscaphites
** †Hoploscaphites birkelundae
** †Hoploscaphites landesi
** †Hoploscaphites macer
** †Hoploscaphites nicolletii
* †Hulettia – report made of unidentified related form or using admittedly obsolete nomenclature
** †Hulettia hawesi – type locality for species
* †Hypsirophus – type locality for genus
** †Hypsirophus discurus – type locality for species

## I

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* †Ichthyodectes
* †Ignotornis – type locality for genus
** †Ignotornis mcconnelli – type locality for species
* Fossilized shell of the Early Jurassic-Late Cretaceous marine bivalve Inoceramus with a human indicating its size †Inoceramus
** †Inoceramus altus
** †Inoceramus altusiformis
** †Inoceramus anomalus
** †Inoceramus arnoldi
** †Inoceramus balticus
** †Inoceramus brancoiformis
** †Inoceramus bueltenensis
** †Inoceramus cordiformis
** †Inoceramus crippsi – or unidentified related form
** †Inoceramus deformis
** †Inoceramus erectus
** †Inoceramus flavus
** †Inoceramus grandis
** †Inoceramus longealatus
** †Inoceramus muelleri - or unidentified loosely related form
** †Inoceramus oblongus
** †Inoceramus pictus
** †Inoceramus prefragilis
** †Inoceramus rutherfordi – or unidentified comparable form
** †Inoceramus tenuistriatus – tentative report
* †Ischyrhiza
** †Ischyrhiza avonicola – or unidentified comparable form

## J

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* Fossilized shell of the Late Cretaceous ammonoid cephalopod Jeletzkytes †Jeletzkytes
** †Jeletzkytes brevis
** †Jeletzkytes dorfi
** †Jeletzkytes nodosus
* †Jensensispermum
** †Jensensispermum redmondii
* Jupiteria
** †Jupiteria scitula

## K

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* †Kepodactylus – type locality for genus
** †Kepodactylus insperatus – type locality for species

## L

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* †Laosaurus – report made of unidentified related form or using admittedly obsolete nomenclature
* Laternula
* Lepisosteus – tentative report
** †Lepisosteus occidentalis
* †Leptalestes – tentative report
** †Leptalestes cooki
* Restoration of a school of the Middle Triassic-Early Cretaceous bony fish Leptolepis †Leptolepis – or unidentified comparable form
* †Lewyites
** †Lewyites oronensis
* Lima
** †Lima janetae – type locality for species
* †Lingula
* †Lioestheria
** †Lioestheria tendagurensis – or unidentified comparable form
* †Lisserpeton
** †Lisserpeton bairdi
* †Lonchidion
** †Lonchidion selachos
* †Lucina
* †Lyropecten

## M

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* Diagram illustrating the known fossil material of two specimens of the Late Jurassic crocodile relative Macelognathus †Macelognathus
** †Macelognathus vagans
* †Magadiceramus
** †Magadiceramus complicatus
** †Magadiceramus crenelatus
** †Magadiceramus soukupi - or unidentified loosely related form
** †Magadiceramus subquadratus
* †Magnoavipes
** †Magnoavipes caneeri – type locality for species
* †Marmarthia – or unidentified comparable form
** †Marmarthia pearsonii
* †Marshosaurus – or unidentified comparable form
* Fossilized skull of the Late Cretaceous multituberculate mammal Meniscoessus †Meniscoessus
** †Meniscoessus collomensis – type locality for species
** †Meniscoessus conquistus
** †Meniscoessus robustus – or unidentified comparable form
* †Mesadactylus – type locality for genus
** †Mesadactylus ornithosphyos – type locality for species
* †Mesembrioxylon
** †Mesembrioxylon carterii – type locality for species
* †Mesodma
** †Mesodma formosa – or unidentified comparable form
* †Mesojassoides – type locality for genus
** †Mesojassoides gigantea – type locality for species
* †Mesolanistes
** †Mesolanistes reesidei
* †Metengonoceras
** †Metengonoceras dumbli
* †Metoicoceras
** †Metoicoceras geslinianum
* †Micrabacia
** †Micrabacia radiata
* †Micropycnodon
** †Micropycnodon kansasensis
* †Modiolus
** †Modiolus kremmlingensis – type locality for species
** †Modiolus meeki
* †Moremanoceras
** †Moremanoceras scotti
* †Morosaurus
** †Morosaurus laticollis – type locality for species
* †Morrolepis
** †Morrolepis schaefferi – type locality for species
* †Myledaphus
** †Myledaphus bipartitus
* Mounted fossilized skeleton of the Late Jurassic armored dinosaur Mymoorapelta †Mymoorapelta – type locality for genus
** †Mymoorapelta maysi – type locality for species
* Myrica
** †Myrica torreyi
* †Mytiloides
** †Mytiloides duplicostatus – or unidentified related form
** †Mytiloides latus – or unidentified comparable form
** †Mytiloides mytiloides
** †Mytiloides opalensis
** †Mytiloides stantoni – or unidentified comparable form
** †Mytiloides submytiloides – or unidentified related form

## N

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* †Nanosaurus – type locality for genus
** †Nanosaurus agilis – type locality for species
** †Nanosaurus rex
* Multiple views of a fossilized shell belonging to a Natica moon snail Natica
* †Nemodon
** †Nemodon adkinsi
** †Nemodon harriesi – type locality for species
* †Neocardioceras
** †Neocardioceras densicostatum – type locality for species
** †Neocardioceras juddii
** †Neocardioceras laevigatum
** †Neocardioceras minutum
** †Neocardioceras uptonense
* †Neocrioceras
* †Neoptychites
** †Neoptychites cephalotus
* †Neurankylus
* †Nigericeras
** †Nigericeras scotti – type locality for species
* †Nonactaeonina
** †Nonactaeonina deflexa
** †Nonactaeonina triticea
* †Nortedelphys
** †Nortedelphys jasoni
* Restoration of several species of the Late Cretaceous ammonoid cephalopod Nostoceras †Nostoceras
** †Nostoceras approximans – or unidentified comparable form
** †Nostoceras larimerense – type locality for species
** †Nostoceras monotuberculatum
** †Nostoceras obtusum – or unidentified comparable form
** †Nostoceras splendidum – or unidentified comparable form
* Nucula
** †Nucula percrassa
* Nuculana
* †Nymphalucina
** †Nymphalucina bourni – type locality for species
** †Nymphalucina cleburni

## O

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* †Octopodichnus
* †Odaxosaurus
** †Odaxosaurus piger
* †Oligoptycha
** †Oligoptycha concinna
* †Opertochasma
** †Opertochasma cuneatum
* †Opisthias
* †Opisthotriton
** †Opisthotriton kayi
* †Ornitholestes – tentative report
* †Ornithomimipus
** †Ornithomimipus angustus – or unidentified comparable form
* Fossilized skeleton of the Late Cretaceous ostrich dinosaur Ornithomimus †Ornithomimus – type locality for genus
** †Ornithomimus velox – type locality for species
* Ostrea
** †Ostrea beloiti
** †Ostrea subradiata
* †Othnielia – tentative report
* †Othnielosaurus
** †Othnielosaurus consors
* †Oxybeloceras
** †Oxybeloceras crassum
* †Oxytoma

## P

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* Fossilized skull of the Late Cretaceous dome-headed dinosaur Pachycephalosaurus †Pachycephalosaurus
* †Pachyrhizodus
** †Pachyrhizodus minimus
* †Palaeobalistum
* †Palaeopteryx – type locality for genus
* †Paleonelumbo
** †Paleonelumbo macroloba
* †Parabrontopodus – type locality for genus
** †Parabrontopodus mcintoshi – type locality for species
* †Parallelodon
* †Paramacellodus
* †Parapleurites
** †Parapleurites morrisonensis – type locality for species
* †Paressonodon – type locality for genus
** †Paressonodon nelsoni – type locality for species
* †Parikimys – type locality for genus
** †Parikimys carpenteri – type locality for species
* †Parviraptor
* Life restoration of the Late Cretaceous horned dinosaur Pentaceratops †Pentaceratops
** †Pentaceratops sternbergii
* †Pentasauropus
* †Petropteron – type locality for genus
** †Petropteron mirandum – type locality for species
* †Phelopteria
** †Phelopteria linguaeformis
** †Phelopteria ruppii – type locality for species
* †Phlycticrioceras
** †Phlycticrioceras trinodosus
* †Pinna
* †Placenticeras
** †Placenticeras meeki
** †Placenticeras placentum
** †Placenticeras syrtale
* †Plastomenus – tentative report
** †Plastomenus insignis – type locality for species
** †Plastomenus punctulatus – type locality for species
* †Platanites
** †Platanites marginata
* Fossilized shell of the Cretaceous marine bivalve Platyceramus †Platyceramus
** †Platyceramus ahsenensis
** †Platyceramus cycloides
** †Platyceramus mantelli - or unidentified loosely related form
** †Platyceramus platinus
* †Platyognathus
* †Plesiobaena
** †Plesiobaena antiqua – or unidentified comparable form
* †Polyonax – type locality for genus
** †Polyonax mortuarius – type locality for species
* †Preprismatoolithus
** †Preprismatoolithus coloradensis
* †Priacodon
** †Priacodon fruitaensis – type locality for species
* †Prionocyclus
* †Probaena
** †Probaena sculpta – type locality for species
* Fossilized skull of the Late Cretaceous mosasaur Prognathodon †Prognathodon
** †Prognathodon overtoni
** †Prognathodon stadtmani – type locality for species
* Propeamussium
** †Propeamussium simplicus
* †Protalphadon
* †Protexanites
** †Protexanites shoshonensis
* †Protocardia
** †Protocardia barneyi – type locality for species
* †Protocupressinoxylon
** †Protocupressinoxylon medlynii – type locality for species
* †Protolambda
** †Protolambda hatcheri
* Life restoration of the Late Cretaceous bony fish Protosphyraena †Protosphyraena
* Prunus
** †Prunus corrugis
* †Pseudaspidoceras
** †Pseudaspidoceras collignoni
* †Pseudobaculites
* †Pseudocalycoceras
** †Pseudocalycoceras angolaense
** †Pseudocalycoceras dentonense
* †Pseudoisurus
** †Pseudoisurus tomosus – or unidentified comparable form
* †Pseudoperna
** †Pseudoperna bentonensis
** †Pseudoperna congesta
** †Pseudoperna inflatum – type locality for species
* †Pseudotetrasauropus – tentative report
* †Pteraichnus
* †Ptychodus
** †Ptychodus anonymus
** †Ptychodus decurrens
** †Ptychodus occidentalis
** †Ptychodus whipplei
* †Puebloites
** †Puebloites spiralis
* Pycnodonte
** †Pycnodonte newberryi

## R

* A
* B
* C
* D
* E
* F
* G
* H
* I
* J
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* L
* M
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* O
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* R
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* T
* U
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* W
* X
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* †Rhaeboceras
** †Rhaeboceras coloradoense – type locality for species
** †Rhaeboceras halli
** †Rhaeboceras subglobosum
* A living Rhinobatos guitar fish Rhinobatos
** †Rhinobatos incertus
* †Rhynchosauroides
* †Rosselia
* †Rotodactylus

## S

* A
* B
* C
* D
* E
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* H
* I
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* M
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* X
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* †Sabalites
** †Sabalites JC016 – informal
** †Sabalites LA042 – informal
* †Saurillodon
* †Scapherpeton
** †Scapherpeton tectum
* Fossilized shell of the Late Cretaceous ammonoid cephalopod Scaphites †Scaphites
** †Scaphites binneyi
** †Scaphites depressus
** †Scaphites hippocrepis – or unidentified comparable form
** †Scaphites nodosus
* †Schadipes – type locality for genus
** †Schadipes crypticus – type locality for species
* †Sciponoceras
** †Sciponoceras gracile
* †Scoyenia
* †Selaginella
** †Selaginella JC023 – informal
* Fossilized skeleton of the Late Triassic-Early Jurassic bony fish Semionotus †Semionotus
* †Solenoceras
** †Solenoceras larimerense
** †Solenoceras reesidei – or unidentified comparable form
** †Solenoceras texanum
* †Sphenodiscus
** †Sphenodiscus pleurisepta
* †Spiroxybeloceras
** †Spiroxybeloceras meekanum
* Squalicorax
** †Squalicorax curvatus
** †Squalicorax falcatus
** †Squalicorax pristodontus
* †Squatirhina
** †Squatirhina americana
* Restoration of the Late Jurassic stegosaur Stegosaurus †Stegosaurus – type locality for genus
** †Stegosaurus armatus – type locality for species
** †Stegosaurus stenops – type locality for species
** †Stegosaurus ungulatus
* †Steinerocaulis
** †Steinerocaulis radiatus
* †Stenomyti – type locality for genus
** †Stenomyti huangae – type locality for species
* †Stokesosaurus – or unidentified comparable form
* †Stramentum
** †Stramentum haworthi
* Sulcoretusa
** †Sulcoretusa dominici – type locality for species
* †Sumitomoceras
** †Sumitomoceras bentonianum
** †Sumitomoceras conlini
* Restoration in multiple views of the Late Jurassic sauropod dinosaur Supersaurus with an anachronistic human to scale †Supersaurus – type locality for genus
** †Supersaurus vivianae – type locality for species
* †Syncyclonema
** †Syncyclonema travisanus
* †Synorichthys – type locality for genus
** †Synorichthys stewarti – type locality for species

## T

* A
* B
* C
* D
* E
* F
* G
* H
* I
* J
* K
* L
* M
* N
* O
* P
* Q
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* W
* X
* Y
* Z
* †Tanaocrossus – type locality for genus
** †Tanaocrossus kalliokoskii – type locality for species
* †Tanocrossus
* Tellina
* †Tenea
** †Tenea parilis
* Teredo
** †Teredo irregularis
* †Texanites
** †Texanites americanus
* Fossilized skeleton of the Late Cretaceous plesiosaur Thalassomedon †Thalassomedon – type locality for genus
** †Thalassomedon hanningtoni – type locality for species
* †Theiophytalia – type locality for genus
** †Theiophytalia kerri – type locality for species
* †Therangospodus – or unidentified comparable form
* †Thescelosaurus
* †Tibiaporrhais
** †Tibiaporrhais cooperensis
* †Titanosaurus
** †Titanosaurus montanus – type locality for species
* Fossilized skulls of the Late Cretaceous horned dinosaurs Torosaurus (A) and Triceratops (B) to scale †Torosaurus
** †Torosaurus latus
* †Torvosaurus – type locality for genus
** †Torvosaurus tanneri – type locality for species
* †Trachybaculites
** †Trachybaculites columna – or unidentified comparable form
* †Treptichnus
* †Triceratops
** †Triceratops galeus – type locality for species
** †Triceratops horridus
* †Trinacromerum – or unidentified comparable form
* Trochocyathus
** †Trochocyathus egerius
* †Turbinopsis
* Turritella
* †Turseodus
** †Turseodus dolorensis – type locality for species
* †Tylosaurus
** †Tylosaurus proriger
* Fossilized skeleton of the Late Cretaceous tyrannosaur Tyrannosaurus †Tyrannosaurus
** †Tyrannosaurus rex

## V

* A
* B
* C
* D
* E
* F
* G
* H
* I
* J
* K
* L
* M
* N
* O
* P
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* W
* X
* Y
* Z
* †Vanikoropsis
** †Vanikoropsis nebrascensis
* Fossilized shell of the Late Cretaceous ammonoid cephalopod Vascoceras †Vascoceras
** †Vascoceras birchbyi
* Viviparus
** †Viviparus reesidei
* †Volviceramus
** †Volviceramus grandis
** †Volviceramus involutus
* †Voysa

## W

* A
* B
* C
* D
* E
* F
* G
* H
* I
* J
* K
* L
* M
* N
* O
* P
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* R
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* T
* U
* V
* W
* X
* Y
* Z
* †Walteria – type locality for genus
** †Walteria jeffersonensis – type locality for species
** †Walteria jeffersoni – type locality for species
* †Watinoceras
** †Watinoceras coloradoense – type locality for species
* †Websteria
** †Websteria cretacea
* †Worthoceras

## X

* A
* B
* C
* D
* E
* F
* G
* H
* I
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* L
* M
* N
* O
* P
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* T
* U
* V
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* X
* Y
* Z
* †Xenoxylon
** †Xenoxylon moorei – type locality for species
* Life restoration of the Cretaceous bony fish Xiphactinus †Xiphactinus
** †Xiphactinus audax

## Z

* A
* B
* C
* D
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* F
* G
* H
* I
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* L
* M
* N
* O
* P
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* R
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* T
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* V
* W
* X
* Y
* Z
* †Zyziphus
** †Zyziphus fibrillosus
** †Zyziphus LA007 – informal
** †Zyziphus LA032 – informal