Gravigrade xenarthrans from the early Pleistocene Leisey Shell Pit 1A, Hillsborough County, Florida

Abstract

Two taxa of ground sloths are present at Leisey Shell Pit 1A Nothrotheriops texanus and Paramylodon harlani. The Irvingtonian sample of Nothrotheriops is sufficiently distinct morphologically to warrant separation from the Rancholabrean species, N. shastensis, and is referred to Nothrotheriops texanus (Hay) (new combination). Individuals of the Irvingtonian P. harlani average smaller than those of the Rancholabrean and there is a general size increase in the lineage from the Blancan to Rancholabrean with only minor morphological changes. Use of Paramylodon instead of Glossotherium for the species P. harlani is nomenclaturally correct.