Opinions from R. C. Hulbert and F. C. Whitmore 2006
- 'Aphelops belongs to Rhinocerotidae'
- 'Aphelops mutilus belongs to Aphelops'
- 'Artiodactyla belongs to Mammalia'
- 'Borophaginae belongs to Canidae'
- 'Camelidae belongs to Artiodactyla'
- 'Canidae belongs to Carnivora'
- 'Canis (Epicyon) was reranked as Epicyon and belongs to Borophaginae'
- 'Canis (Epicyon) haydeni is recombined as Epicyon haydeni'
- 'Carnivora belongs to Mammalia'
- 'Cetacea was reranked as a suborder and belongs to Cete'
- 'Cete belongs to Mammalia'
- 'Cormohipparion belongs to Hipparionini'
- 'Cormohipparion emsliei belongs to Cormohipparion'
- 'Dicotyles serus is recombined as Prosthennops serus'
- 'Dromomerycidae was reranked as the subfamily Dromomerycinae and belongs to Palaeomerycidae'
- 'Equidae belongs to Perissodactyla'
- 'Equus (Protohippus) was reranked as Protohippus and belongs to Protohippini'
- 'Equus eurystylus is recombined as Neohipparion eurystyle'
- 'Gelocidae belongs to Artiodactyla'
- 'Gomphotheriidae belongs to Proboscidea'
- 'Hipparion (Nannippus) was reranked as Nannippus and belongs to Hipparionini'
- 'Hipparionini belongs to Equidae'
- 'Lamini belongs to Camelidae'
- 'Nannippus aztecus belongs to Nannippus'
- 'Neohipparion belongs to Hipparionini'
- 'Odontoceti was reranked as a unranked clade and belongs to Cetacea'
- 'Palaeomerycidae belongs to Artiodactyla'
- 'Pediomeryx belongs to Dromomerycinae'
- 'Perissodactyla was reranked as a order and belongs to Mammalia'
- 'Platanistina was reranked as the family Platanistidae and belongs to Odontoceti'
- 'Pleiolama belongs to Lamini'
- 'Pliauchenia vera is recombined as Pleiolama vera'
- 'Pomatodelphis belongs to Platanistidae'
- 'Pomatodelphis inaequalis belongs to Pomatodelphis'
- 'Proboscidea belongs to Mammalia'
- 'Prosthennops belongs to Tayassuidae'
- 'Protoceratidae belongs to Artiodactyla'
- 'Protohippini belongs to Equinae'
- 'Protohippus gidleyi belongs to Protohippus'
- 'Pseudoceras belongs to Gelocidae'
- 'Rhinocerotidae belongs to Perissodactyla'
- 'Synthetoceras belongs to Synthetoceratinae'
- 'Synthetoceras davisorum belongs to Synthetoceras'
- 'Synthetoceratinae belongs to Protoceratidae'
- 'Taperidae is corrected as Tapiridae and belongs to Perissodactyla'
- 'Tapirus belongs to Tapiridae'
- 'Tayassuidae belongs to Artiodactyla'
- 'Teleoceras belongs to Rhinocerotidae'