A REVISION OF NORTH AMERICAN EARLY EOCENE BRONTOTHERIIDAE (MAMMALIA, PERISSODACTYLA)

Graduate Thesis Or Dissertation

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/3197xn16j

Abstract

North American brontotheriid classification and phylogeny needs drastic revision. The earliest known brontotheriids, from the late early Eocene (late Wasatchian land mammal age) of Colorado and Wyoming, are poorly represented in the fossil record, but appear to lie near although not at the origin of this slowly evolving, dentally conservative perissodactyl family. Taxonomic revision here reduces five previously accepted species of Eotitanops to two, one of questionable validity, and reallocates these species to Palaeosyops. Palaeosyops becomes the oldest known brontotheriid genus. The type specimen of Palaeosyops fontinalis, from the lowermost Bridger Formation (Bridger A) of earliest middle Eocene age, is placed in synonymy with Palaeosyops paludosus from the immediately overlying Bridger B. Because of this synonymy, a new trivial name, huerfanensis, is required for latest Wasatchian Palaeosyops from the upper faunal assemblage of the Huerfano Formation, Huerfano Basin, Colorado.

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