Late Miocene three-toed horse Protohippus (Mammalia, Equidae) from southern Alabama

Abstract

Dental and postcranial remains of a donkey-sized, three-toed, primitive horse were collected from the “Undifferentiated Miocene” Ecor Rouge Sand (which underlies the widespread Citronelle Formation) from the Mauvilla site in southern Alabama. These fossils probably pertain to a single individual of Protohippus gidleyi Hulbert, 1988. This represents an exceedingly rare occurrence of a late Tertiary land mammal from the central Gulf Coastal Plain and allows comparisons with better-known, contemporaneous land-mammal assemblages from Florida. Based on the known biochronology of Protohippus gidleyi from other localities, and the stratigraphic position of the Mauvilla record, the age of: 1) the Ecor Rouge Sand is late Miocene (latest Clarendonian to early Hemphillian landmammal “age”), between 9.0 to 6.5 Ma; and 2) the overlying Citronelle Formation near its type locality in southern Alabama is therefore late Miocene or younger.