Natural Trap, Large Amerhippus, Text
LARGE AMERHIPPUS
– A fragmentary skull, KU 51330, resembles one specimen from Tarija, Bolivia: the basicranial proportions are similar, and like in most Amerhippus the muzzle is very wide (Fig.1).
– The upper premolars of KU 56806 are similar to another specimen from Tarija. I refer to the same species an upper P2, KU 26472 (Fig.2).
– In the lower cheek teeth associated with the skull the M1 and M2 have elongated and bilobated metaconids as frequently occurs in Amerhippus (Fig.3); I refer to the same species the P2-M3 KU 41528 and the P2-P4 42589.
– A first anterior phalanx, KU 26478, is almost identical to the mean of A. occidentalis of Rancho La Brea (Fig.4).
– I refer to the same species one tibia (Fig.5), five or six tali (Fig.6,7), and one calcaneum (Fig.8,9).
– Given the data I have, the sorting of Ph3 into anterior and posterior is almost impossible. Among the large Ph3, the specimen KU 50821 could be a posterior Ph3 of a Caballine or an anterior of A. occidentalis. Others could belong to a very large A. occidentalis (Fig.10).
LARGE ?AMERHIPPUS
Two MC of the same individual may or may not belong to the same species (Fig.11).