The easternmost occurrence of the Late Miocene schizotheriine chalicothere Ancylotherium pentelicum at the classical locality of Maragheh (Iran)

Abstract

The renowned Late Miocene locality of Maragheh (northwest Iran) has yielded ample material of chalicotheres, most of which has never been described in detail. The present study concerns the taxonomic evaluation of this material and its attribution to the large schizotheriine Ancylotherium pentelicum. This allows a detailed comparison to schizotheriine material from other localities, and based on this, we provide an overview of the diagnostic features of Ancylotherium that separate it from all other chalicotheres. This improves our understanding of the type species A. pentelicum. Additionally, we discuss the palaeobiogeography of the species, which is best known from the Balkan Peninsula. Maragheh marks the easternmost occurrence of A. pentelicum, but its presence has even been suggested in Africa. Lastly, we discuss the existence of sexual size dimorphism in the species, based on the herein described material along with previously described specimens of A. pentelicum from other fossil sites, such as the famous Late Miocene localities Pikermi and Samos (Greece). Specifically, it is shown that many postcranial elements exhibit great size variability that is most probably associated with significant sexual dimorphism.