<i>Mammut pacificus</i>sp. nov., a newly recognized species of mastodon from the Pleistocene of western North America

Abstract

A new species of mastodon from the Pleistocene of western North America, <i>Mammut pacificus</i> sp. nov. is herein recognized, with specimens identified throughout California and from two localities in southern Idaho. This new taxon differs from the contemporaneous <i>M. americanum</i> in having narrower teeth, most prominently in M3/m3, as well as six sacral vertebrae, femur with a proportionally greater mid-shaft diameter, and no mandibular tusks at any growth stage. All known Pleistocene <i>Mammut</i> remains from California are consistent with our diagnosis of <i>M. pacificus</i>, which indicates that <i>M. americanum</i> was not present in California.