Pliocene Three-toed Horses From Louisiana. With Comments on the Citronelle Formation

Abstract

Teeth and metacarpals of early Pliocene (latest Hemphillian land-mammal age) three-toed (hipparionine) horses are described from the Tunica Hills of West Feliciana Parish in east-central Louisiana. An upper molar pertains to Nannippus minor, known from the Hemphillian of Central and North America, and two teeth and two distal metacarpals pertain to a recenlly described species of Cormohipparion, C. emsliei, known only from Pliocene (latest Hemphillian and Blancan land mammal ages) sites in peninsular Florida. The material represents the first record of Pliocene non-marine fossils from Louisiana as well as the first record of' a fossil horse from the state other than Pleistocene Equus. Found in surface stream gravels, the horses probably were derived from the otherwise almost nonvertabrate-bearing Citronelle Formation.