Opinions from L. B. Radinsky 1966
- 'Allacerops belongs to Hyracodontidae'
- 'Amynodontidae belongs to Rhinocerotoidea'
- 'Ardynia belongs to Hyracodontidae'
- 'Colodon belongs to Helaletinae'
- 'Colonoceras is a subjective synonym of Hyrachyus'
- 'Cooperia is replaced by Forstercooperia'
- 'Dilophodon belongs to Helaletinae'
- 'Eggysodon belongs to Hyracodontidae'
- 'Eotrigonias belongs to Hyracodontidae'
- 'Ephyrachyus is a subjective synonym of Hyrachyus'
- 'Epiaceratherium belongs to Rhinocerotidae'
- 'Forstercooperia belongs to Hyracodontidae'
- 'Helaletes belongs to Helaletinae'
- 'Helaletidae belongs to Rhinocerotoidea'
- 'Helaletinae belongs to Helaletidae'
- 'Heptodon belongs to Helaletinae'
- 'Hyrachyidae was reranked as the subfamily Hyrachyinae and belongs to Helaletidae'
- 'Hyrachyus belongs to Hyrachyinae'
- 'Hyracodon belongs to Hyracodontidae'
- 'Hyracodontidae belongs to Rhinocerotoidea'
- 'Indricotherium belongs to Hyracodontidae'
- 'Juxia belongs to Hyracodontidae'
- 'Metahyrachyus is a subjective synonym of Hyrachyus'
- 'Pappaceras belongs to Hyracodontidae'
- 'Paraceratherium belongs to Hyracodontidae'
- 'Praeaceratherium belongs to Hyracodontidae'
- 'Prohyracodon belongs to Hyracodontidae'
- 'Prothyracodon belongs to Hyracodontidae'
- 'Rhinocerotidae belongs to Rhinocerotoidea'
- 'Trigonias belongs to Rhinocerotidae'
- 'Triplopus belongs to Hyracodontidae'
- 'Urtinotherium belongs to Hyracodontidae'