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1 April 2009 Skeletal Morphology of a New Genus of Eocene Insectivore (Mammalia, Erinaceomorpha) from Utah
Rachel H. Dunn, D. Tab Rasmussen
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A new genus and 2 new species of erinaceomorph insectivores from the Eocene of Utah are named and described. Both come from Member B of the Uinta Formation, which consists of terrestrially deposited rocks of Early Uintan age. The best specimen consists of dentaries, a few teeth, and several associated elements of the postcranial skeleton; additional dental and postcranial remains also have been recovered. Dentally, the new genus resembles the smaller erinaceomorphs known from earlier in the Rocky Mountain region of North America rather than the contemporary large ones from southern California, indicating that large body size and omnivory evolved independently in different regions of North America during the Eocene. The new genus is primitive in lacking many specializations of the ankle seen in extant erinaceids and other Eocene insectivores. The morphology of the forelimb suggests some digging behavior in having an expanded entepicondyle and the presence of distinct tubercles for insertion of the extensor carpi radialis on the bases of metacarpals II and III. The hind limb exhibits a mosaic of features typical of terrestrial runners, such as anteroposteriorly deep femoral condyles and a deep patellar groove, along with features seen in arboreal climbers, such as a medially and plantarly inflected calcaneal heel. We conclude that the new genus was terrestrial, perhaps moving rapidly over an uneven substrate such as a littered forest floor, but it could probably dig and climb as well.

Rachel H. Dunn and D. Tab Rasmussen "Skeletal Morphology of a New Genus of Eocene Insectivore (Mammalia, Erinaceomorpha) from Utah," Journal of Mammalogy 90(2), 321-331, (1 April 2009).
Received: 27 February 2008; Accepted: 1 July 2008; Published: 1 April 2009

functional morphology
locomotor behavior
Mammalian evolution
Uinta Formation
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