Natural Trap, Large Amerhippus, Text


 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).


Two MC of the same individual may or may not belong to the same species (Fig.11).