Associated Upper and Lower Cheek Teeth
KNM ER 2652 are an upper right Premolar and the mesial half of a left Premolar (Fig.53).
Both are very plicated thus differing strongly from all the Koobi Fora specimens younger than NS zone. The pli caballin is wide at its base. Both teeth remind of Sussemiones .
Other Upper Cheek Teeth
Unlike the precedent, the teeth belonging to the fragment of palate KNM ER 1457 (Fig. 54) are not plicated. Post-protoconal valleys are shallow, protocones are short, symmetrical and lingually grooved.
They may belong to the larger form described and referred to ?Allohippus sp. above (see KNM ER 2691 from MA zone in Fig. 31). If the post-protoconal grooves were deeper, they would look like Ass teeth. One isolated premolar, KNM ER 2684, Area 6A, has indeed a deep groove (Fig. 55). FS 101, without origin, has a similar pattern. But on the molar KNM ER 2066, the groove is shallow.
Lower Cheek Teeth
There are no other lower cheek teeth than the specimen illustrated on Fig. 54.