NEW DATA ON HESPERORNITHIDS (AVES: ORNITHURAE) FROM THE CAMPANIAN OF THE LOWER VOLGA REGION (LATE CRATACEOUS, RUSSIA)

Taxonomic diversity of the Late Cretaceous Hesperornithidae (Aves: Hesperornithidae) of the European part of Russia and Eastern Europe as a whole remain poorly understood, and the morphology of these large flightless birds is poorly known. New finds of Hesperornithidae in the Karyakino locality (Saratov oblast, Russia) confirm the coexistence of two forms of these flightless seabirds in the Campanian (mid-Late Cretaceous) of the Lower Volga region. For Hesperornis rossicus Nessov et Yarkov, 1993, a femur is described for the first time; it indicates a morphological distinctiveness of this large species as compared to the North American H. regalis Marsh, 1872.