Palaeosyops fontinalis ( Cope 1873a )

Mader, Bryn J., 2010, A species-level revision of the North American brontotheres Eotitanops and Palaeosyops (Mammalia, Perissodactyla), Zootaxa 2339, pp. 1-43 : 38-39

Species Palaeosyops fontinalis ( Cope 1873a)

= P. huerfanensis ( Osborn 1919)

Holotype: AMNH 5107, a fragmentary juvenile skull with the right DP4 and M1–2 preserved. Referred specimens: AMNH 17411, AMNH 17412 (type of P. huerfanensis ), AMNH 17425, UW 3039, UW3091.

Diagnosis: Small-sized species of Palaeosyops (based on AMNH 17411, UW 3039, and UW 3091, length of P2 to M3 is approximately 123 to 144 mm) that may be distinguished from P. paludosus and P. robustus by its smaller size and perhaps by the more plesiomorphic structure of P2 and relatively small fronto-parietal dome.

Discussion: As indicated in the Discussion section for the genus Palaeosyops , I provisionally recognize specimens of Palaeosyops from Bridger A as being taxonomically distinct from P. paludosus from Bridger B. The size range of P. fontinalis overlaps with that of P. paludosus , however, and the P 2 in one specimen referred to P. fontinalis (UW 3039) is not as plesiomorphic as that of UW 3091. The type of P. fontinalis is from Bridger A, and I tentatively refer all of the Palaeosyops material from this level to that species. Additional statistical and morphological analysis will be required to confirm whether P. fontinalis is valid and, if valid, whether all of the material from Bridger A can be referred to this taxon.

I also tentatively refer specimens of Palaeosyops from the Huerfano Formation to P. fontinalis because of their relatively small size and because there is no basis at present for distinguishing them from specimens of Palaeosyops from Bridger A. Assignment of the Huerfano specimens to P. fontinalis must be regarded as very uncertain, however, until more material is available for examination. As noted in the Discussion section for the genus Palaeosyops , above, if it should later prove that the Huerfano specimens represent a distinct species, then the name P. huerfanensis (Osborn) may apply.