59.4  Jan. 7  A Systematic Revision of the Agriochoeridae (Cetartiodactyla: Oreodontoidea) LUDTKE, JA; San Diego State University joshualudtke@gmail.com

Oreodonts, despite being a common component of Tertiary North American terrestrial faunas, lack a firm phylogenetic placement within Cetartiodactyla. Most workers agree that they are an early diverging`group, but disagreement exists as to whether oreodonts are more closely related to ruminant, suid, or tylopod artiodactyls. The earliest appearing branch of Oreodontoidea is the clade Agriochoeridae, which is defined by the retention of several ancestral character states, such as an incomplete postorbital bar and a lack of lacrimal fossae. Some members of this clade are unique among Cetartiodactyla in developing clawed ungual phalanges. As currently defined, Agriochoeridae is paraphyletic, as it contains basal oreodonts, true agriochoerid oreodonts, and basal members of the highly successful oreodontid oreodonts. In addition, the named genera within Agriochoeridae, Protoreodon, Diplobunops, and Agriochoerus, are in need of taxonomic revision. Protoreodon contains several independent evolutionary lineages, Diplobunops might simply be early species of Agriochoerus, and several other species are known but lack a published diagnosis, definition, or name.

Reorganization of the species and supra-species level systematics of the Agriochoeridae is necessary to allow the proper placement of Oreodontoidea in cetartiodactylan systematics. This investigation uses measurements and observations of dental, cranial, and postcranial morphology to diagnose and describe members of Agriochoeridae at the species level. At least fifteen species in this clade can be distinguished, mostly by a combination of dental row size and the cusp development of the upper and lower fourth premolar. These characters are used to place the agriochoerid species into a phylogenetic taxonomy. This information will be used to further refine the placement of Agriochoeridae and Oreodontoidea within Cetartiodactyla.