H. matthewi group and Hipparion sp. from Q5.
The type skull (Abel 1926 ; Sondaar 1971, pl.IVa) belongs to the Budapest collections (UGR OK 557). The exact origin of the skull is unknown. There is a cast of it at the British Museum in London.
The specimen is very small, with a very short muzzle, a short naso-incisival notch, and a very faint preorbital fossa (POF). Although it belonged to an old male, there is something ‘juvenile’ in the rounded cranium. On the whole, it looks like a miniature of the Darmstadt or Chicago H. dietrichi crania but with a narrower muzzle.
At Q1, four more or less fragmentary specimens (AMNH 20625, 20626, 20628, and 94906) are slightly larger but show approximately the same proportions as H. matthewi. Forsten did not relate them to H. matthewi as I do (probably because their POF are more marked than in the type H. matthewi) but distinguished them from H. detrichi, putting them in a separate group. AMNH 94905 is a subadult specimen with a weak fossa and a long muzzle.
At Q5, six small skulIs (albeit not as small as the type) have been referred to H. matthewi both by Forsten and Sondaar. Sondar (1971, p.423) remarked that their muzzles are considerably longer than in the type but interpreted that as a matter of individual variation.
However, the dimensions of the mandibular diastema (Sondaar 1971, tab. II) fall clearly into two groups : short in type H. matthewi and Q1 specimens AMNH C5 and A, longer in AMNH 22898 and 22928 of the same quarry. I believe that only the first (and smaller) mandibles represent H. matthewi in Q1 whereas the other mandibles belong to the Hipparion of Q5, which is intermediate in size between H. matthewi and H. dietrichi but not related to either of them.