Opinions from E. C. Galbreath 1953
- 'Aceratherium megalodum is recombined as Aphelops megalodus'
- 'Aceratherium profectum is recombined as Aphelops profectus'
- 'Aciprion belongs to Iguanidae'
- 'Ammodon potens is recombined as Archaeotherium potens'
- 'Anchisodon is a subjective synonym of Subhyracodon'
- 'Ankylodon progressus belongs to Ankylodon'
- 'Apternodus iliffensis belongs to Apternodus'
- 'Archaeotherium belongs to Entelodontidae'
- 'Archaeotherium mortoni belongs to Archaeotherium'
- 'Bathornis belongs to Bathornithidae'
- 'Bunaelurus is a subjective synonym of Palaeogale'
- 'Bunaelurus lagophagus is recombined as Palaeogale lagophaga'
- 'Buteo belongs to Accipitridae'
- 'Caenopus persistens is recombined as Diceratherium persistens'
- 'Calamagras belongs to Boidae'
- 'Canis gregarius is recombined as Pseudocynodictis gregarius'
- 'Canis hartshornianus is recombined as Daphoenus hartshornianus'
- 'Canis lippincottianus is recombined as Pseudocynodictis lippincottianus'
- 'Canis lippincottianus is recombined as Pseudocynodictis lippincottianus' according to Schlosser 1902
- 'Canis lippincottianus is recombined as Galecynus lippincottianus' according to Cope 1884
- 'Canis temerarius is recombined as Tomarctus temerarius'
- 'Canis vafer is recombined as Leptocyon vafer'
- 'Cervus warreni is recombined as Merycodus warreni'
- 'Cosoryx is a subjective synonym of Merycodus'
- 'Cosoryx furcatus is recombined as Merycodus furcatus'
- 'Cremastosaurus belongs to Sauria'
- 'Cynodictis hylactor is a subjective synonym of Pseudocynodictis lippincottianus'
- 'Cynodictis paterculus is recombined as Pseudocynodictis paterculus'
- 'Cynodictis paterculus is recombined as Pseudocynodictis paterculus' according to Clark 1937
- 'Cynodictis temnodon is recombined as Pseudocynodictis temnodon'
- 'Cynodictis temnodon is recombined as Pseudocynodictis temnodon' according to Matthew 1918
- 'Daptophilus squalidens is recombined as Dinictis squalidens'
- 'Diacium belongs to Sauria'
- 'Diacium unipedalis is recombined as Cremastosaurus unipedalis' according to E. D. Cope 1874
- 'Diplolophus parvus is recombined as Proheteromys parvus'
- 'Dipoides curtus is recombined as Monosaulax curtus'
- 'Domnina compressa belongs to Domnina'
- 'Drassonax belongs to Amphicyonidae'
- 'Drassonax harpagops belongs to Drassonax'
- 'Elotherium bathrodon is a subjective synonym of Archaeotherium ramosus'
- 'Elotherium crassum is recombined as Archaeotherium crassum'
- 'Elotherium ramosum is recombined as Archaeotherium ramosus'
- 'Exostinus belongs to Iguanidae'
- 'Exostinus serratus belongs to Exostinus'
- 'Glyptosaurus belongs to Anguidae'
- 'Gopherus belongs to Testudinidae'
- 'Gymnoptychus minutus is recombined as Adjidaumo minutus'
- 'Gymnoptychus trilophus is recombined as Paradjidaumo trilophus'
- 'Heloderma belongs to Helodermatidae'
- 'Herpetotherium is a subjective synonym of Peratherium'
- 'Herpetotherium fuzax is recombined as Peratherium fugax'
- 'Herpetotherium fuzax is recombined as Peratherium fugax' according to Cope 1884
- 'Herpetotherium huntii is recombined as Peratherium huntii'
- 'Herpetotherium huntii is recombined as Peratherium huntii' according to Cope 1884
- 'Hipparion coloradense is recombined as Neohipparion coloradense'
- 'Hippotherium paniense is recombined as Merychippus paniensis'
- 'Hippotherium sphenodus is recombined as Merychippus sphenodus'
- 'Hyaenodon horridus belongs to Hyaenodon'
- 'Hypohippus osborni belongs to Hypohippus'
- 'Hyporhina belongs to Hyporhinidae'
- 'Hyracodon apertus is a subjective synonym of Hyracodon nebraskensis'
- 'Hyracodon arcidens is a subjective synonym of Hyracodon nebraskensis'
- 'Hyracodon leidyanus is a subjective synonym of Hyracodon nebraskensis'
- 'Hyracodon quadriplicatus is a subjective synonym of Subhyracodon occidentalis'
- 'Hyracodon selenidens is a subjective synonym of Hyracodon nebraskensis'
- 'Ischyromys pliacus is a subjective synonym of Ischyromys typus'
- 'Leidymys vetus is a subjective synonym of Eumys exiguus'
- 'Leptauchenia calcarata is recombined as Hypertragulus calcaratus'
- 'Leptauchenia minima is recombined as Hypisodus minimus'
- 'Machairodus primaevus is recombined as Hoplophoneus primaevus'
- 'Martes ogygia is recombined as Plionictis ogygia'
- 'Mastodon merriami is recombined as Mammut merriami'
- 'Mastodon merriami is recombined as Mammut merriami' according to Hay 1930
- 'Mastodon merriami is recombined as Miomastodon merriami' according to Osborn 1942
- 'Mastodon merriami is recombined as Miomastodon merriami' according to Osborn 1926
- 'Mastodon proavus is recombined as Serridentinus proavus'
- 'Mastodon proavus is recombined as Serridentinus proavus' according to Osborn 1936
- 'Mastodon productus is recombined as Serridentinus productus'
- 'Megaceratops is a subjective synonym of Megacerops'
- 'Megaceratops acer is recombined as Megacerops acer'
- 'Menotherium lemurinum is recombined as Stibarus lemurinus'
- 'Merychippus eoplacidus belongs to Merychippus'
- 'Merychyus medius is recombined as Ustatochoerus medius'
- 'Merycochoerus magnus is a subjective synonym of Merycochoerus proprius'
- 'Merycodus gemmifer is recombined as Blastomeryx gemmifer'
- 'Merycodus osborni is recombined as Ramoceros osborni'
- 'Merycoidodon belongs to Merycoidodontidae'
- 'Merycoidodon culbertsonii belongs to Merycoidodon'
- 'Miothen is a subjective synonym of Domnina'
- 'Miothen crassigenis is a subjective synonym of Domnina gradata'
- 'Moropus matthewi is recombined as Macrotherium matthewi'
- 'Moropus matthewi is recombined as Macrotherium matthewi' according to Matthew 1929
- 'Moropus matthewi belongs to Moropus' according to Holland and Peterson 1913
- 'Mustela parviloba is recombined as Plionictis parviloba'
- 'Mylagaulus paniensis is recombined as Mesogaulus paniensis'
- 'Neurodromicus belongs to Crotalidae'
- 'Merycoidodon periculorum is a subjective synonym of Merycoidodon culbertsonii'
- 'Oreodon gracile is recombined as Merycoidodon gracilis'
- 'Oreodon major is recombined as Eporeodon major'
- 'Palaeocrex belongs to Rallidae'
- 'Palaeocrex fax belongs to Palaeocrex' according to Wetmore 1927
- 'Palaeogyps belongs to Cathartidae'
- 'Palaeogyps prodromus belongs to Palaeogyps' according to Wetmore 1927
- 'Palaeolagus turgidus is recombined as Megalagus turgidus'
- 'Paramys relictus is recombined as Prosciurus relictus'
- 'Pelonax is a subjective synonym of Archaeotherium'
- 'Peltosaurus belongs to Anguidae'
- 'Pelycomys belongs to Allomyidae'
- 'Pelycomys placidus belongs to Pelycomys'
- 'Pelycomys rugosus belongs to Pelycomys'
- 'Phalacrocorax belongs to Phalacrocoracidae'
- 'Phalacrocorax mediterraneus belongs to Phalacrocorax' according to Shufeldt 1915
- 'Phasmagyps belongs to Cathartidae'
- 'Phasmagyps patritus belongs to Phasmagyps' according to Wetmore 1927
- 'Platyrhachis rhambastes belongs to Platyrhachis' according to E. D. Cope 1884
- 'Plesiosminthus clivosus belongs to Plesiosminthus'
- 'Procamelus angustidens is recombined as Protolabis angustidens'
- 'Procamelus fissidens is recombined as Protolabis fissidens'
- 'Procamelus heterodontus is recombined as Protolabis heterodontus'
- 'Protohippus labrosus is a nomen dubium'
- 'Protohippus proplacidus is recombined as Merychippus proplacidus'
- 'Protomeryx campester belongs to Protomeryx'
- 'Protomeryx cedrensis is a subjective synonym of Protomeryx campester'
- 'Protosorex is a subjective synonym of Domnina'
- 'Protosorex crassus is a subjective synonym of Domnina gradata'
- 'Rhineura belongs to Amphisbaenidae'
- 'Rhinoceros nebraskensis is recombined as Hyracodon nebraskensis'
- 'Stylemys belongs to Emydidae'
- 'Testudo belongs to Testudinidae'
- 'Testudo cultrata is a nomen dubium' according to Williams 1950
- 'Testudo laticuneus [misspelled as Gopherus laticunea] belongs to Gopherus' according to Williams 1950
- 'Testudo pansa [misspelled as Gopherus pansa] belongs to Gopherus' according to Williams 1950
- 'Testudo quadratus is a nomen dubium' according to Williams 1950
- 'Trigonias cooki is a subjective synonym of Trigonias osborni'
- 'Trigonias hypostylus is a subjective synonym of Trigonias osborni'
- 'Trigonias precopei is a subjective synonym of Trigonias osborni'
- 'Trigonias preoccidentalis is a subjective synonym of Trigonias osborni'
- 'Trigonias taylori is a subjective synonym of Trigonias osborni'
- 'Trigonias taylori is a subjective synonym of Trigonias osborni' according to Figgins 1934
- 'Xestops belongs to Anguidae'