Hyopsodus wortmani (replica)

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Hyopsodus was a small mammal that differs from all living mammals. Fossil remains attributed to this genus are restricted to Eocene strata, with multiple species known (Archibald, 1998). Hyopsodus ranged in size from a rat to a raccoon and had an elongated body, short legs, and a protruding rostrum with sharp incisors at the tip of its skull. The latter features suggest it likely had a rooting habit while foraging for food on the ground (Gazin, 1968). Hyopsodus is one of the most common land mammal found in Eocene layers of North America, but most of these abundant fossil finds consist of fragmentary remains (e.g., teeth or small skeletal fragments)(Gazin, 1968). Paradoxically, only one specimen of Hyopsodus is known from the Green River Formation (reproduced in this replica), but it is articulated and fairly complete (Grande, 2013). Therefore, exceptional conditions of preservation make even single specimens invaluable in filling knowledge gaps that would otherwise remain open. Fossils of this genus have been found in the United States, Canada, Mexico, Europe, China, Mongolia and Japan (Paleobiology Database, n.d.).

References:

Archibald, J.D., 1998. Archaic ungulates (“Condylarthra”). In: C.M., Janis, K.M., Scott, and L.L., Jacobs (eds.), Evolution of Tertiary Mammals of North America. Volume 1: Terrestrial Carnivores, Ungulates, and Ungulatelike Mammals. Cambridge University Press, Cambridge. pp. 292–331.

Gazin, C.L., 1968. A study of the Eocene condylarthran mammal Hyopsodus. Smithsonian Miscellaneous Collections. 153(4). pp. 1-90.

Grande, L., 2013. The lost world of Fossil Lake: Snapshots from deep time. University of Chicago Press. p. 425.

Paleobiology Database, (no date). Hyopsodus. The Paleobiology Database. Available at: https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=42250 (Accessed: March 2025).