Ungulates of the Toledo Bend Local Fauna (Late Arikareean, Early Miocene), Texas Coastal Plain

Abstract

The Toledo Bend Local Fauna includes the most diverse assemblage of mammals yet reported from the earliest Miocene Gulf Coastal Plain. Faunal affinities with the Buda Local Fauna of northern Florida, as well as with faunas of the northern Great Plains and Oregon, suggest a "medial" to late Arikareean age. Of 26 mammalian taxa represented, the 17 ungulates are discussed in this report; the carnivores, small mammals, and lower vertebrates are discussed elsewhere. All ungulate taxa are browsers rather than grazers, and many have not previously been recorded from the Gulf Coastal Plain. Riparian forms such as anthracotheres and tapirs account for a large percentage of mammalian remains recovered, although horses, rhinoceroses, and a small, new species of protoceratid, Prosynthetoceras orthrionanus sp. nov., are also common. Other ungulates include a small chalicothere, a new small rhinoceros, Gulfoceras westfalli gen. et sp. nov., and a giant entelodonts. The abundance of protoceratids, tapirs, anthracotheres, and rhinoceroses, the absence of oreodonts, and the rarity of camelids at Toledo Bend contrasts with Arikareean faunas in Florida where protoceratids and anthracotheres are absent, tapirs and rhinos are extremely rare, oreodonts are present, and camelids are relatively common.