A reappraisal of Sarmatosminthus, the earliest member of lophocricetine jerboas (Rodentia, Dipodidae) from Eastern Europe

The subfamily Lophocricetinae is a diverse group of fossil dipodids, with the earliest known records dating back to the Late Oligocene and Early Miocene. Most members of the group are known from Asia, with only a few taxa documented from the Late Miocene of Eastern Europe. Currently, the earliest known European lophocricetine is the genus Sarmatosminthus , first described in 1981 from the Late Miocene of Moldova. However, the status and validity of the genus remained elusive for decades, as it has been either neglected or synonymized with Heterosminthus . We examined the type material of Sarmatosminthus , as well as new material from Vallesian sites of Moldova and Romania and compared it with other lophocricetine taxa. We suggest the synonymy of the genus with Heterosminthus is not supported, and Sarmatosminthus should be considered as a valid taxon. In comparison with the former, Sarmatosminthus lacks the connections between the hypocone and posterocone, and the mesoloph and mesostyle on the M1, and has a different configuration of the protostyle on the M1 and the hypoconid on the m1.