Miocene and Pliocene artiodactyls, Texas Gulf Coastal Plain

Abstract

Describes 27 species of fossil artiodactyls from a series of vertically successive mammalian. assemblages in Miocene and Pliocene deposits of the Texas Gulf Coastal Plain and discusses their systematic positions. Among the new forms represented are two camel genera: Australocamelus, the probable Aepycamelus ancestor, and Nothotylopus, a very unusual member of the Protolabis-Pliauchenia lineage. The Floridagulinae are now seen to have had a trans-Coastal Plain distribution extending in time from the middle Hemingfordian Garvin Gully Fauna through the Barstovian Cold Spring Fauna. The Gulf Coast species of the Synthetoceratinae are discussed and the phylogeny of the subfamily outlined. Evidence from this study indicates that the Gulf Coastal Plain constituted a distinct faunal province throughout most of the Tertiary. Whereas many striking similarities exist between the faunas of the Texas Coastal Plain and those of the Great Plains, several groups are true Gulf Coast autochthons. Others, which are distributed in both regions, contain species endemic to the Gulf Coastal Plain. The ages of the Texas Gulf Coastal Plain faunas are revised and correlated with those from the Great Plains.