Full reference: M. C. McKenna. 1975. Toward a phylogenetic classification of the Mammalia. Phylogeny of the Primates, Plenum Publishing, New York 21-46
Parent taxon: Panperissodactyla according to T. J. D. Halliday et al. 2017
See also Archibald 1998, Gheerbrant et al. 2001 and McKenna 1975
Sister taxa: Panameriungulata, Perissodactylamorpha
Subtaxa: Olbitherium Phenacodontidae
Ecology: scansorial insectivore
Distribution:
• Eocene of Belgium (2 collections), China (2), France (3), Germany (1), Mexico (2), the United Kingdom (1), United States (469: California, Colorado, Mississippi, New Mexico, Texas, Utah, Wyoming)
• Cf2 of United States (2: Wyoming)
• Cf3 of United States (2: Wyoming)
• Cf1 of United States (1: Wyoming)
• Clarkforkian of United States (281: Colorado, Montana, Wyoming)
• Paleocene to Eocene of United States (2: California, Wyoming)
• Paleocene of Canada (15: Alberta, Saskatchewan), United States (189: California, Colorado, Maryland, Montana, New Mexico, North Dakota, Texas, Wyoming)
• Tertiary of Spain (1)
Total: 973 collections including 1290 occurrences