A new atoposaurid crocodylomorph from the Morrison Formation (Upper Jurassic) of Wyoming, USA

  • John R. Foster Utah Field House of Natural History State Park Museum
Keywords: Upper Jurassic, Morrison Formation, Theriosuchus, atoposaurid, crocodylomorph

Abstract

A left mandible of a small crocodyliform found in the Upper Jurassic Morrsion Formation of northeastern Wyoming represents the first occurrence of the atoposaurid Theriosuchus in North America. The specimen demonstrates lower jaw morphology, including heterodonty (as indicated by alveolus shape), similar to Theriosuchus and Knoetschkesuchus, but autapomorphies and a unique combination of characters among these taxa indicate that it is a distinct, new species of Theriosuchus.

The Little Houston Quarry (Mammal Pit), in the lower middle right of the photograph, is in the Morrison Formation of the northwestern Black Hills, Crook County, Wyoming, which yielded the crocodyliform jaw described here.
Published
2018-12-21
How to Cite
Foster, J., 2018, A new atoposaurid crocodylomorph from the Morrison Formation (Upper Jurassic) of Wyoming, USA: Geology of the Intermountain West, v. 5, p. 287-295.