Ekgmowechashala (Mammalia, ?Primates) from the Gulf Coastal Plain

Abstract

A single, small, water-worn tooth from the “middle” Arikareean Toledo Bend Local Fauna of the Gulf Coastal Plain closely resembles the lower fourth premolar of the questionable primate Ekgmowechashala. The only known species of the genus, Ekgmowechashala philotau Macdonald (1963), was originally recovered from the early Arikareean Sharps Formation of South Dakota, but is also known from similar aged strata of the John Day Formation, Oregon. Although the Toledo Bend specimen differs somewhat in morphology from the p4 of E. philotau, a new species is not named in this report because of such limited material and because the specimen is incomplete. Unfortunately, the specimen does not provide information that helps clarify current arguments regarding the affinities of Ekgmowechashala with primates or plagiomenids. It does, however, provide (1) a temporal range extension for the genus to the early late Arikareean, or about four million years younger than previously known, and (2) a geographic extension east and considerably south of its prior distribution. If Ekgmowechashala is ultimately determined to belong to the Primates, then the Toledo Bend species would become the last known North American representative of the order.