Dental variation in the molars of Mammuthus columbi var. M. imperator (Proboscidea, Elephantidae) from a Mathis gravel quarry, southern Texas

Abstract

A large sample ( N = 149 ) of Mammuthus columbi molars was excavated from a gravel quarry of Rancholabrean North American Land Mammal Age (NALMA) near Mathis, San Patricio County in southern Texas. This attritional assemblage, which also includes Xenarthra, Equidae, Camelidae, Cervidae, and Bovidae, was recovered from fluvial point-bar deposits. Standard mammoth dental measurements and metrics (enamel thickness, plate width, plate number, and lamellar frequency) from a minimum of 25 individuals vary widely. The number of plates in the tooth (PN) is the most reliable measurement in the identification of the molar to the species level. Enamel thickness and lamellar frequency suggest that the Mathis sample represents a local population of Mammuthus columbi that approaches molar morphologies found in Irvingtonian NALMA populations usually placed in M. imperator.