List of the Mesozoic life of Wyoming

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

A

• †Abielites
  • †Abielites angusticarpus

• 

  Acipenser
  • †Acipenser eruciferus
• †Acutostrea
  • †Acutostrea plumosa
• †Adocus
• †Agathaumas – type locality for genus
  • †
    Agathaumas sylvestris
    – type locality for species
• †Agerostrea
  • †Agerostrea mesenterica
• †Agialopous – type locality for genus
  • †Agialopous wyomingensis – type locality for species

• 

  †Albanerpeton
  • †
    Albanerpeton galaktion
  • †
    Albanerpeton nexuosus
    – type locality for species
• †Albertosaurus – or unidentified comparable form
• †Alethesaurus – type locality for genus
  • †Alethesaurus quadratus – type locality for species
• †Aletridelphys
  • †Aletridelphys florencae – type locality for species
  • †Aletridelphys hatcheri
• †Allacodon
  • †Allacodon lentus – type locality for species
  • †Allacodon pumilis – type locality for species
• †Allognathosuchus

• 

  †Allosaurus – type locality for genus
  • †
    Allosaurus fragilis
    – type locality for species
  • †
    Allosaurus jimmadseni
• †Alostera
  • †Alostera saskatchewanensis – type locality for species
• †Alphadon
  • †
    Alphadon attaragos
    – type locality for species
  • †
    Alphadon halleyi
  • †
    Alphadon marshi
  • †
    Alphadon sahnii
• †Altacreodus
  • †
    Altacreodus magnus
• †Alzadites
  • †Alzadites westonensis – type locality for species
• †Amblotherium – type locality for genus
  • †Amblotherium gracilis – type locality for species
• †Amborellites – type locality for genus
  • †Amborellites wyomingensis – type locality for species

• Amia

  • †Amia fragosa
  • †Amia uintaensis

• †Amphicoelias
  • †
    Amphicoelias brontodiplodocus
    – type locality for species
• †Amphidon – type locality for genus
  • †
    Amphidon superstes
    – type locality for species
• †Anaklinoceras
  • †Anaklinoceras mortoni
• †Anaschisma – type locality for genus
  • †Anaschisma brachygnatha – type locality for species
  • †Anaschisma browni – type locality for species
• †Anceptophyllum – type locality for genus
  • †Anceptophyllum pulcrum – type locality for species
• †Anchura – tentative report
• †Ancorichnus
• †Andromeda
  • †Andromeda grayana
• †Anemia
  • †Anemia fremonti
  • †Anemia subcretacea

• 

  †Angistorhinus – type locality for genus
  • †
    Angistorhinus aeolamnis
    – type locality for species
  • †
    Angistorhinus gracilis
    – type locality for species
  • †
    Angistorhinus grandis
    – type locality for species
  • †
    Angistorhinus maximus
    – type locality for species
• †Anisoceras
• †Anisomyon
  • †Anisomyon borealis
  • †Anisomyon centrale
  • †Anisomyon patelliformis
  • †Anisomyon subovatus – or unidentified related form
  • †Anisomyon subovulatus
• †Ankistrorhynchus
  • †Ankistrorhynchus washakiensis – type locality for species

• 

  †Ankylosaurus
  • †
    Ankylosaurus magniventris
• †Anomalofusus – tentative report
• Anomia
  • †Anomia tellinoides
• Anona
  • †Anona robusta – tentative report
• †Anthrotaxopsis
  • †Anthrotaxopsis tenuicaulis
• Antrimpos
• †Apatodonosaurus
  • †Apatodonosaurus grayi
• †Apatosaurinae
  • †Apatosaurinae – type locality for genus – informal

• 

  †Apatosaurus
  • †
    Apatosaurus louisae
  • †
    Apatosaurus minimus
• †Apeibopsis – tentative report
  • †Apeibopsis discolor
• †Aploconodon – type locality for genus
  • †
    Aploconodon comoensis
    – type locality for species
• Aporrhais
  • †Aporrhais biangulata
• †Aquilina – type locality for genus
  • †Aquilina grossidentata – type locality for species
• Aralia
  • †Aralia veatchii
• †Araliaephyllum
  • †Araliaephyllum artocarpoides

• 

  Araucaria
• †Araucarites
  • †Araucarites cuneatus – type locality for species
  • †Araucarites longifolia
  • †Araucarites wyomingensis – type locality for species
• Arca – report made of unidentified related form or using admittedly obsolete nomenclature
• †Arcellites
  • †Arcellites disciformis
• †Archaeotriakis
  • †Archaeotriakis ornatus – type locality for species
  • †Archaeotriakis rochelleae
• †
  Archaeotrigon
  – type locality for genus
  • †Archaeotrigon brevimaxillus – type locality for species

• 

  †Arcticoceras
• †Arenicolites
• †Aristolochites
  • †Aristolochites brittoni
• †Ascarinites – type locality for genus
  • †Ascarinites communis – type locality for species
• Aspideretes
• †Aspideretoides
  • †Aspideretoides foveatus – or unidentified comparable form
• †Asplenites
  • †Asplenites tenellum

• 

  †Asplenium
  • †Asplenium haguei
  • †Asplenium neomexicanum
  • †Asplenium occidentale
• †Astandes
  • †Astandes densatus
• †
  Astarta
  • †Astarta packardi
• Astarte
  • †Astarte gregaria
  • †Astarte livingstonensis
  • †Astarte meeki
  • †Astarte morion
• †Athrotaxopsis
  • †Athrotaxopsis tenuicaulis
• † Atira – tentative report
  • †Atira nebrascensis
• †Atokatheridium – or unidentified comparable form

• 

  †Aublysodon
  • †
    Aublysodon mirandus
• †Austrotindaria
  • †Austrotindaria antiqua
  • †Austrotindaria canalensis
  • †Austrotindaria svalbardensis
• †Avernalia – type locality for genus
  • †Avernalia solida – type locality for species

B

• 

  †Baculites
  • †
    Baculites asper
  • †
    Baculites asperiformis
  • †
    Baculites baculus
  • †
    Baculites clinolobatus
  • †
    Baculites cobbani
  • †
    Baculites codyensis
  • †
    Baculites crickmayi
  • †
    Baculites elaisi
  • †
    Baculites eliasi
  • †
    Baculites gilberti
  • †
    Baculites grandis
  • †
    Baculites gregoryensis
  • †
    Baculites haresi
  • †
    Baculites jenseni
    – or unidentified comparable form
  • †
    Baculites mariasensis
  • †
    Baculites mclearni
  • †
    Baculites obtusus
  • †
    Baculites perplexus
  • †
    Baculites reesidei
  • †
    Baculites rugosus
  • †
    Baculites scotti
• †Baena
  • †Baena hatcheri – type locality for species
  • †Baena hayi – type locality for species
  • †Baena marshi – type locality for species
• †Baieropsis
  • †Baieropsis adiantifolia
  • †Baieropsis pluripartita
• †Baptanodon
  • †Baptanodon discus
  • †Baptanodon reedi – type locality for species
  • †Baptanodon robustus – type locality for species
• Barbatia – tentative report

• 

  †Barosaurus
  • †
    Barosaurus lentus
• †Basilemys
  • †Basilemys sinuosa
• †Batodon
  • †Batodon tenuis – type locality for species
• †Belonostomus
  • †
    Belonostomus longirostris
• Berenicea
• Bombur
• †Borealosuchus
  • †
    Borealosuchus sternbergii
    – type locality for species
• †Boremys
• †Borissiakoceras
  • †Borissiakoceras orbiculatum
• Botula
  • †
    Botula ripleyana

• 

  Brachaelurus
  • †Brachaelurus bighornensis – type locality for species
• †Brachiosaurus
• †
  Brachybrachium
  – type locality for genus
  • †
    Brachybrachium brevipes
    – type locality for species
• †Brachychampsa
  • †
    Brachychampsa montana
• †Brachyphyllum
  • †Brachyphyllum crassum
• †Brontopodus – or unidentified comparable form
  • †Brontopodus birdi

• 

  †Brontosaurus – type locality for genus
  • †
    Brontosaurus excelsus
    – type locality for species
  • †
    Brontosaurus parvus
    – type locality for species
  • †
    Brontosaurus yahnahpin
    – type locality for species
• †Bryceomys
• †Bullopsis
  • †Bullopsis cretacea – or unidentified related form

C

• †Cadoceras
• Callista
  • †Callista deweyi
  • †Callista peplucida
• †Calycoceras
  • †Calycoceras canitaurinum

• 

  †Camarasaurus – type locality for genus
  • †Camarasaurus grandis – type locality for species
  • †Camarasaurus lentus – type locality for species
• †Camborygma
• Campeloma
• †Camptomus
  • †Camptomus amplus – type locality for species
• †Camptonectes
  • †Camptonectes bellistriatus
  • †Camptonectes distans – or unidentified comparable form
  • †Camptonectes platessiformis
  • †Camptonectes stygius

• 

  †Camptosaurus
  • †
    Camptosaurus dispar
    – type locality for species
• † Canna
  • †Canna magnifolia – tentative report
• †Capillirhynchia
  • †Capillirhynchia gallatinensis – type locality for species
• Cardium sp.
• †Carpites
  • †Carpites lancensis
  • †Carpites verrucosus
  • †Carpites walcotti
• †Carpolithus
  • †Carpolithus barrensis – type locality for species
  • †Carpolithus fasciculatus
  • †Carpolithus foenarius – type locality for species
  • †Carpolithus montiumnigrorum – type locality for species
  • †Carpolithus virginiensis
• †Carthaginites
  • †Carthaginites aquilonius – type locality for species
• †Cataceramus
  • †Cataceramus tenuilineatus
• †Cedrobaena
  • †Cedrobaena brinkman
• †Celastrophyllum
  • †Celastrophyllum gyminaefolium

• 

  †Celastrus – tentative report
  • †Celastrus taurinensis
• †Cemeterius – type locality for genus
  • †Cemeterius monstrosus – type locality for species
• †Centrophoroides
  • †Centrophoroides worlandensis – type locality for species
• †Cephalotaxopsis
  • †Cephalotaxopsis magnifolia
• †Ceramornis – type locality for genus
  • †
    Ceramornis major
    – type locality for species
• †
  Ceratodus
  • †Ceratodus frazieri
  • †
    Ceratodus guentheri

• 

  †Ceratosaurus
• Cercidiphyllum
  • †Cercidiphyllum arcticum
  • †Cercidiphyllum ellipticum
• †Cercomya
  • †Cercomya punctata
• †Ceritella
• Cerithium – tentative report
• †Chamops – type locality for genus
  • †Chamops segnis – type locality for species

• 

  †Champsosaurus
  • †Champsosaurus natator
• †Chelonipus – or unidentified comparable form
• Chiloscyllium
  • †Chiloscyllium missouriense
• †Chirotherium
  • †
    Chirotherium barthii
• Chlamys
  • †Chlamys nebrascensis
• †Chondroceras
• †Cimexomys
  • †
    Cimexomys minor
• †Cimolestes
  • †
    Cimolestes incisus
    – type locality for species
  • †
    Cimolestes stirtoni
    – type locality for species
• †Cimolodon
  • †
    Cimolodon nitidus
    – type locality for species
  • †Cimolodon peregrinus – type locality for species

• 

  †Cimolomys
  • †
    Cimolomys clarki
  • †
    Cimolomys gracilis
    – type locality for species
  • †
    Cimolomys parvus
    – type locality for species
• †Cimolopteryx
  • †
    Cimolopteryx maxima
    – type locality for species
  • †
    Cimolopteryx rara
• Cinnamomum
  • †Cinnamomum hesperium
• †Cissitis
  • †Cissitis rocklandensis
• Cissus
  • †Cissus lobato-crenata – tentative report
• †Cladoceramus
  • †Cladoceramus undulatoplicatus – or unidentified related form

• 

  Cladophlebis
  • †
    Cladophlebis parva
  • †
    Cladophlebis readi
    – type locality for species
  • †Cladophlebis readii
  • †
    Cladophlebis wyomingensis
    – type locality for species
• †Claraia
  • †
    Claraia clarai
  • †
    Claraia mulleri
  • †
    Claraia stachei
• †Clemensodon – type locality for genus
  • †
    Clemensodon megaloba
    – type locality for species
• †Clioscaphites
  • †Clioscaphites saxitonianus
  • †Clioscaphites vermiformis
• †Coahuilites
  • †Coahuilites sheltoni
• †Coelostylina
• †Coelosuchus – type locality for genus
  • †Coelosuchus reedii – type locality for species

• 

  †Coelurus – type locality for genus
  • †
    Coelurus fragilis
    – type locality for species
• †Collignoniceras
  • †
    Collignoniceras woollgari
• †Colpodontosaurus – type locality for genus
  • †Colpodontosaurus cracens – type locality for species
• †Comobatrachus – type locality for genus
  • †Comobatrachus aenigmaticus – type locality for species
• †Comodactylus – type locality for genus
  • †
    Comodactylus ostromi
    – type locality for species
• †Comodon – type locality for genus
  • †
    Comodon gidleyi
    – type locality for species
• †Comonecturoides – type locality for genus
  • †Comonecturoides marshi – type locality for species
• †
  Comotherium
  – type locality for genus
  • †Comotherium richi – type locality for species
• †Compsemys
  • †
    Compsemys victa
• †Confusionella
  • †Confusionella loczyi – type locality for species

• 

  †Coniophis – type locality for genus
  • †Coniophis precedens – type locality for species
• †Coniopteris – tentative report
• †Contogenys – or unidentified comparable form
• †
  Corax
• †Corbicella – tentative report
• Corbula
  • †Corbula crassimarginata
  • †Corbula kanabensis
  • †Corbula munda
• †Coriops
  • †
    Coriops amnicolus
• †Cornophyllum
  • †Cornophyllum wardii

• 

  †Corosaurus
  • †
    Corosaurus alcovensis
• Cossmannea
• Crassatella
  • †Crassatella evansi
• †Crassidenticulum
  • †Crassidenticulum aquilae – type locality for species
  • †Crassidenticulum decurrens
• Crenella
• †Cretorectolobus
  • †
    Cretorectolobus olsoni
• †Cryptometoicoceras – type locality for genus
  • †Cryptometoicoceras mite – type locality for species
• †Cryptorhytis
  • †Cryptorhytis cheyennensis
• †Ctenacodon – type locality for genus
  • †
    Ctenacodon laticeps
    – type locality for species
  • †
    Ctenacodon scindens
    – type locality for species
  • †
    Ctenacodon serratus
    – type locality for species
• †Cteniogenys – type locality for genus
  • †Cteniogenys antiquus – type locality for species
• †Ctenostreon
  • †Ctenostreon gikshanensis – or unidentified comparable form

• Cucullaea

  • †Cucullaea haguei
  • †Cucullaea shumardi

• †Cunningtoniceras
• Cuspidaria
  • †Cuspidaria variablis
• †Cycadeospermum
  • †Cycadeospermum rotundatum
• †Cyclurus
  • †Cyclurus fragosus
• †Cylindricum
• †Cymbophora
  • †Cymbophora canonensis – or unidentified comparable form
  • †Cymbophora formosa
  • †Cymbophora holmesi
• †Cyperacites
• †Czekanowskia
  • †Czekanowskia nervosa

D

• †Dakotasaurus – type locality for genus
  • †Dakotasaurus browni – type locality for species
• †Daspletosaurus

• 

  †Deinonychus
  • †
    Deinonychus antirrhopus
• †Delphodon
  • †Delphodon comptus – type locality for species
• †Deltatheroides – or unidentified comparable form
• †Dennstaedtia
  • †Dennstaedtia fremonti
• Dentalium
  • †Dentalium gracile
  • †
    Dentalium pauperculum
• †
  Derrisemys
  • †Derrisemys sterea

• 

  †Desmatosuchus
• †Desmoscaphites
  • †Desmoscaphites bassleri
• †Dewalquea
  • †Dewalquea pulchella
• †Diastopora
  • †Diastopora cutleri – type locality for species
• †Dicellonema
  • †Dicellonema abrekensis
• †Dicotyledon

• 

  †Didelphodon
  • †Didelphodon vorax – type locality for species
• †Didymoceras
  • †Didymoceras nebrascense
  • †
    Didymoceras stevensoni
• †Dillenites
  • †Dillenites cleburni
• †Dinochelys
  • †
    Dinochelys whitei
• †Diospyros
  • †Diospyros stenosepala
• †Diploconcha
• †Diplocraterion
• †Diplodocinae
  • †Diplodocinae – type locality for genus – informal

• 

  †Diplodocus
  • †
    Diplodocus carnegii
    – type locality for species
  • †
    Diplodocus hallorum
  • †
    Diplodocus longus
• †Discoscaphites
• †Docodon – type locality for genus
  • †
    Docodon affinis
    – type locality for species
  • †
    Docodon crassus
    – type locality for species
  • †
    Docodon striatus
    – type locality for species
  • †
    Docodon superus
    – type locality for species
  • †
    Docodon victor
    – type locality for species
• †Dolichobrachium – type locality for genus
  • †Dolichobrachium gracile – type locality for species

• 

  †Dolichorhynchops
  • †
    Dolichorhynchops osborni
• †Dombeyopsis
  • †Dombeyopsis colgatensis
  • †Dombeyopsis obtusa
  • †Dombeyopsis platanoides
  • †Dombeyopsis trivialis
• †Doratodon – tentative report
• †Dorsetisaurus
• †Dosiniopsis
  • †Dosiniopsis deweyi
• †Drepanocheilus
  • †Drepanocheilus evansi
  • †Drepanocheilus nebrascensis
  • †Drepanocheilus obesus
  • †Drepanocheilus scotti – or unidentified comparable form
• †
  Drinker
  – type locality for genus
  • †
    Drinker nisti
    – type locality for species

• 

  †Dromaeosaurus
• †Dryandroides
  • †Dryandroides lanceolata
• †Dryolestes – type locality for genus
  • †
    Dryolestes priscus
    – type locality for species
  • †Dryolestes vorax
• †Dryophyllum – type locality for genus
  • †Dryophyllum lanceolatum
  • †Dryophyllum polymorphum – type locality for species
  • †Dryophyllum subfalcatum
• Dryopteris
  • †Dryopteris coloradensis
• †Dryosaurus
  • †
    Dryosaurus altus
    – type locality for species
• †Dryptosaurus – or unidentified comparable form
• †Dunveganoceras
  • †Dunveganoceras pondi
  • †Dunveganoceras problematicum
• †Dyslocosaurus – type locality for genus
  • †
    Dyslocosaurus polyonychius
    – type locality for species

E

• †Echidnocephalus – tentative report
• †Edmontonia
  • †
    Edmontonia rugosidens
    – or unidentified comparable form
• †Edmontosaurus

  • 

    †Edmontosaurus annectens – type locality for species
• †Egertonodus
• †Elaphrosaurus – tentative report
• †Elasmosaurus
• †Elatides
• †Ellipsoscapha
  • †Ellipsoscapha occidentalis
• †Emarginachelys
• †
  Empo
• †Enneabatrachus – type locality for genus
  • †
    Enneabatrachus hechti
    – type locality for species
• Entalis
  • †Entalis paupercula – tentative report
• †Entalophora
  • †Entalophora stokesi – type locality for species
• †Eobatrachus – type locality for genus
  • †Eobatrachus agilis – type locality for species
• †Eocephalites
  • †Eocephalites primus
• †Eokainaster – type locality for genus
  • †Eokainaster pewei

• 

  †Eopelobates
• †Equisetites
• †Equisetum
  • †Equisetum FF014 – informal
  • †Equisetum RS016 – informal
  • †Equisetum virginicum
• †Essonodon
  • †
    Essonodon browni
• †Estescincosaurus – type locality for genus
  • †Estescincosaurus cooki – type locality for species
• †Eubaena – type locality for genus
  • †Eubaena cephalica – type locality for species

• 

  †Eubostrychoceras
  • †Eubostrychoceras matsumotoi – type locality for species
• †Eubrachiosaurus – type locality for genus
  • †
    Eubrachiosaurus browni
    – type locality for species
• †Eucalycoceras
  • †Eucalycoceras templetonense
• †
  Eucrossorhinus
  • †Eucrossorhinus microcuspidatus
• †Eumorphotis
  • †Eumorphotis multiformis
• †Euomphaloceras
  • †Euomphaloceras merewetheri
• †Eurysalenia
  • †Eurysalenia minima
• †Euspira
  • †Euspira obliquata
• †Euthlastus – type locality for genus
  • †
    Euthlastus cordiformis
    – type locality for species

• 

  †Eutrephoceras
  • †Eutrephoceras montanaense
• †Eutretauranosuchus
  • †
    Eutretauranosuchus delfsi
• †Exiteloceras
  • †Exiteloceras jenneyi
• †Exogyra
  • †
    Exogyra costata
• †Exostinus – type locality for genus
  • †Exostinus lancensis – type locality for species

F

• †Falepetrus
  • †Falepetrus barwini – type locality for species

• 

  Fasciolaria
  • †Fasciolaria flexicostata – tentative report
• †Feistmantelia – type locality for genus
  • †Feistmantelia oblonga – type locality for species
• †Ficophyllum
  • †Ficophyllum serratum
• Ficus
  • †Ficus fremonti
  • †Ficus Fremontii
  • †Ficus inaequalis
  • †Ficus paryearensis
  • †Ficus planicosta
  • †Ficus planicostata
  • †Ficus rockvalensis
  • †Ficus trinervis
• †Filicites
  • †Filicites knowltoni
• †Forresteria
  • †Forresteria stantoni

• 

  †Fosterovenator – type locality for genus
  • †Fosterovenator churei – type locality for species
• †
  Foxraptor
  – type locality for genus
  • †Foxraptor atrox – type locality for species
• †Fraxinus
  • †Fraxinus denticulata
  • †Fraxinus leii

G

• 

  †Galeamopus
  • †
    Galeamopus hayi
  • †
    Galeamopus pabsti
    – type locality for species
• †Gargoyleosaurus
  • †
    Gargoyleosaurus parkpinorum
• †Geinitzia
  • †Geinitzia Jenneyi – type locality for species
• †Geonomites
  • †Geonomites schimperi
• Gerrhonotus – or unidentified comparable form
• †Gervillaria
  • †Gervillaria montanaensis
• †Gervillia
  • †Gervillia dolabrata
  • †Gervillia ussurica – or unidentified comparable form
• †Gilmoremys
  • †
    Gilmoremys lancensis
    – type locality for species
• Ginglymostoma
  • †Ginglymostoma globidens

• 

  Ginkgo
  • †Ginkgo adiantoides – tentative report
• †Glasbius
  • †Glasbius intricatus – type locality for species
• †Gleichenites
  • †Gleichenites sepulta
• †Glyptops – type locality for genus
  • †Glyptops pervicax
  • †Glyptops plicatulus – type locality for species
• Glyptostrobus
  • †Glyptostrobus brookensis

• 

  †Gobiconodon
  • †
    Gobiconodon ostromi
• †Goniomya
  • †Goniomya montanaensis
• †Goniopholis
• †Gracilimanus
  • †Gracilimanus obscurus
• †Grammatodon
  • †Grammatodon haguei
• †Graphidula
  • †Graphidula alleni – or unidentified comparable form

  • 

    †Graphidula culbertsoni
• †Grewiopsis
  • †Grewiopsis saportana
• †Gryphaea
  • †Gryphaea nebrascensis
  • †Gryphaea planoconvexa
• †Gypsonictops
  • †Gypsonictops hypoconus – type locality for species
  • †Gypsonictops lewisi
• †Gypsonicus
  • †Gypsonicus wyomingensis

H

• †Habrosaurus – type locality for genus
  • †
    Habrosaurus dilatus
    – type locality for species
• †Hadrosauropodus
• †Halymenites
  • †Halymenites major
• †Hamites
  • †Hamites cimarronensis
  • †Hamites novimexicanus
  • †Hamites salebrosus

• 

  †Haplocanthosaurus
• †Haptosphenus – type locality for genus
  • †Haptosphenus placodon – type locality for species
• †Haresiceras
  • †Haresiceras natronense
• †Harpactognathus – type locality for genus
  • †
    Harpactognathus gentryii
    – type locality for species
• †Hatcheritherium – type locality for genus
  • †Hatcheritherium alpha – type locality for species
• †Hausmannia
  • †Hausmannia AF017
• †Helopanoplia
  • †Helopanoplia distincta
• Hemiaster
  • †Hemiaster humphreysanus

• 

  †Heptasuchus – type locality for genus
  • †
    Heptasuchus clarki
    – type locality for species
• †Herpetarius
  • †Herpetarius humilis
• †Hesperornithoides – type locality for genus^[1]
  • †
    Hesperornithoides miessleri – type locality for species^[1]
• †Hesperosaurus – type locality for genus
  • †
    Hesperosaurus mjosi
    – type locality for species
• †Heteroceras
  • †Heteroceras cochleatum – tentative report
• †Homomya
  • †Homomya gallatinensis
• †Hoploscaphites^[2]
  • †
    Hoploscaphites birkelundae
    – type locality for species
  • †
    Hoploscaphites gilli
  • †Hoploscaphites macer^[2]
  • †
    Hoploscaphites nodosus
  • †
    Hoploscaphites plenus
  • †
    Hoploscaphites quadrangularis
• †Hummelichelys
  • †Hummelichelys beecheri – type locality for species

• 

  †Hybodus
  • †
    Hybodus montanensis
  • †
    Hybodus wyomingensis
    – type locality for species
• †Hyperodapedon
  • †
    Hyperodapedon sanjuanensis
    – or unidentified comparable form
• †Hypotodus
  • †Hypotodus grandis
• †Hypsodon – tentative report
  • †Hypsodon radiatulus

I

• 

  †Ichthyodectes
• †Icthyodectes – tentative report
• †Icthyodesctes – tentative report
• †Idiohamites
  • †Idiohamites bispinosus
• †Iguanavus
  • †Iguanavus teres – type locality for species

• 

  †Inoceramus
  • †
    Inoceramus agdjakendensis
    – or unidentified comparable form
  • †
    Inoceramus americanus
    – type locality for species
  • †
    Inoceramus anglicus
  • †
    Inoceramus balchii
  • †
    Inoceramus barabini
  • †
    Inoceramus crispii
  • †
    Inoceramus deformis
  • †
    Inoceramus dimidius
  • †
    Inoceramus erectus
    – or unidentified related form
  • †
    Inoceramus fibrosus
  • †
    Inoceramus fragilis
    – or unidentified related form
  • †
    Inoceramus gibbosus
  • †
    Inoceramus glacierensis
  • †
    Inoceramus grandis
  • †
    Inoceramus incurvus
  • †
    Inoceramus lundbreckensis
  • †
    Inoceramus perplexus
  • †
    Inoceramus prefragilis
  • †
    Inoceramus proximus
    – or unidentified related form
  • †
    Inoceramus sagensis
  • †
    Inoceramus subcircularis
  • †
    Inoceramus subcompressus
  • †
    Inoceramus sublaevis
  • †
    Inoceramus tenuirostratus
  • †
    Inoceramus tenuiumbonatus
    – or unidentified comparable form
  • †
    Inoceramus turgidus
    – or unidentified related form
  • †
    Inoceramus typicus
  • †
    Inoceramus umbonatus
  • †
    Inoceramus undabundus
• †Ischyrhiza

  • Ischyrhiza avonicola

    – type locality for species

  • †
    Ischyrhiza basinensis
    – type locality for species
  • †
    Ischyrhiza mira
• Isocrinus
  • †Isocrinus knighti
  • †Isocrinus wyomingensis
• †Isocyprina
  • †Isocyprina cinnabarensis
• Isognomon
  • †Isognomon perplana – or unidentified comparable form
• Isurus – tentative report

J

• †Janumys
• †Jeletzkytes
  • †
    Jeletzkytes dorfi
    – type locality for species
• †Jensensispermum
• †Judithemys
  • †Judithemys backmani

K

• †Kaatedocus – type locality for genus
  • †
    Kaatedocus siberi
    – type locality for species
• †
  Koskinonodon
  – type locality for genus
  • †Koskinonodon perfectus – type locality for species

L

• †Lamarqueavis
  • †Lamarqueavis minima – type locality for species
  • †Lamarqueavis petra – type locality for species
• †Lamiasaura – type locality for genus
  • †Lamiasaura ferox – type locality for species
• †Lanceosaurus – type locality for genus
  • †Lanceosaurus compressus – type locality for species
  • †Lanceosaurus hatcheri – type locality for species
• †Laolestes – type locality for genus
  • †
    Laolestes eminens
    – type locality for species
  • †
    Laolestes goodrichi
    – type locality for species
  • †
    Laolestes oweni
    – type locality for species
• †Laopteryx – type locality for genus
  • †Laopteryx priscus – type locality for species
• †Laosaurus – type locality for genus
  • †
    Laosaurus celer
    – type locality for species
• †Laurophyllum
  • †Laurophyllum coloradensis
  • †Laurophyllum meeki
  • †Laurophyllum salicifolium
  • †Laurophyllum wardiana
• Laurus
  • †Laurus aspensis – type locality for species
• †Lepidotes – or unidentified related form
• Lepisosteus
  • †Lepisosteus occidentalis
• †Leptalestes
  • †
    Leptalestes cooki
    – type locality for species
  • †
    Leptalestes krejcii

• 

  †Leptoceratops
  • †
    Leptoceratops gracilis
• †Leptochamops
  • †Leptochamops denticulatus – type locality for species
  • †Leptochamops thrinax
• †Leptochondria
  • †Leptochondria occidanea
• †Leptostrobus
  • †Leptostrobus alatus – type locality for species
  • †Leptostrobus longifolia
  • †Leptostrobus longifolius
• †Lesterwardia – type locality for genus
  • †Lesterwardia palustris – type locality for species
• †Leucichthyops
  • †Leucichthyops vagans
• †Leucicthyops
  • †Leucicthyops vagans
• Lima
  • †Lima occidentalis
• Lingula
  • †Lingula nitida – or unidentified comparable form
• †Lingularia
  • †Lingularia borealis
• †Lioplacodes – or unidentified comparable form
• †Liostrea
  • †Liostrea strigilecula
• Liquidambar
  • †Liquidambar fontanella – type locality for species
• †Lisserpeton
  • †
    Lisserpeton bairdi

• 

  †Lissodus
  • †Lissodus griffisi – type locality for species
• †Litakis – type locality for genus
  • †Litakis gilmorei – type locality for species
• †Lonchidion – type locality for genus
  • †Lonchidion selachos – type locality for species
• †Lonchisaurus – type locality for genus
  • †Lonchisaurus trichurus – type locality for species
• †Lonchodytes – type locality for genus
  • †
    Lonchodytes estesi
    – type locality for species
  • †Lonchodytes pterygius – type locality for species
• †Lophochelys

• Lunatia moon sea snail

  Lucina