Late Neogene Neohipparion (Mammalia, Equidae) from the Gulf Coastal Plain of Florida and Texas

Abstract

Three successive species of Neohipparion are recognized from the Gulf Coastal Plain: N. affine from the early Clarendonian Lapara Creek Fauna of Texas; N. trampasense from the very late Clarendonian and early Hemphillian of Florida; and N. eurystyle from the late early and late Hemphillian of Florida. Numerous specimens from the Love Site, Alachua County, Florida, as well as from other faunas of similar age from Florida, Kansas, and Nebraska (e.g., the Xmas-Kat Quarries), are referred to N. trampasense. This species is ancestral to all later species of Neohipparion, as it shares with them many advanced dental characters, but often in a rudimentary or intermediate form. Five valid species constitute the monophyletic genus Neohipparion, which ranges from the late Barstovian to the latest Hemphillian (late Miocene through earliest Pliocene) in North America. A close phylogenetic relationship between Neohipparion and “Merychippus” republicanus and/or Pseudhipparion is proposed based on similarities of cranial and dental features.