Hyopsodontidae is an extinct
family of primitive
mammals initially assigned to the order
Condylarthra, living from the
Paleocene to the
Eocene in
North America and
Eurasia. Condylarthra is now thought to be a
wastebasket taxon; hyopsodontids have occasionally been speculated to be related to
Afrotheria,[1] but the most recent consensus is that they are related to
Perissodactyla. Analysis of the inner ear shows shared characteristics with the Equoidea (horses and paleotheres);[2] they may be a basal
ungulate group near to perissodactyls.[3]
They were generally small
omnivores, like many early mammals. The most common genus is Hyopsodus.
Members of the family were small by modern standards, ranging in size from a small rat to a raccoon. The hyopsodontids had many primitive mammal characteristics, including five-toed feet with claws and a complete dentition: a full set of incisors, canines, premolars, and molars. During the Paleocene in Europe, they reached a high diversity level, starting with Louisina and Monshyus in
Hainin, Belgium, and following in the
Cernaysian beds with Tricuspiodon, Paratricuspiodon, and Paschatherium.[4] High levels of diversity are also seen in Western North America in the Eocene within the genus Hyopsodus, with up to 18 named species, some of which are specific to particular locations over short spans of geologic time. This pattern suggests that at least some hyosodontids became quite specialized for specific ways of life. The group was not especially long-lived, but highly successful for its time, with fossil material in some areas suggesting large numbers of individuals.[5]
^Kihm, A.J.; Hartman, J.H. (December 2004). "A reevaluation of the biochronology of the Brisbane and Judson local faunas (late Paleocene) of North Dakota". Bulletin of Carnegie Museum of Natural History. 2004 (36): 97–107.
doi:
10.2992/0145-9058(2004)36[97:AROTBO]2.0.CO;2.
^Thewisson, J.G.M. (1991). "Limb Osteology and function of the primitive Paleocene ungulate Pleuraspidotherium with notes on Tricuspiodon and Dissacus (Mammalia)". Geobios. 24 (4): 483–495.
doi:
10.1016/S0016-6995(06)80249-4.