Eutherian mammals from the Early Cretaceous of Mongolia

A collection of eutherian mammals consisting of 39 specimens (teeth and jaw fragments) from the ?Aptian or Albian Khoboor Beds in the Gobi Desert, Mongolia, is described. It contains 3 taxa: Prokenna1estes gen.n., assigned to the Otlestidae Nessov, new rank, with 2 shrew size species; P. trofimovi sp.n. and P. minor sp.n.; a heavily worn larger lower molar which will be described elsewhere. It cannot be excluded that P. trofimovi and P. minor are only sexual morphs within the same species. Prokennalestes and Bobolestes Nessov are possibly the oldest known eutherian mammals, but Prokennalestes is morphologically more primitive than Bobolestes. It has a labial mandibular foramen, 5 premolars and 3 molars, 3 cusps in parastylur region, paracone larger than metacone, unwinged conules, no pre- and posteingula, and lower molars with a 3-cusped talonid, which is narrower than the trigonid, Otlestes and Kennalestes may be derived with little modification from Prokennalestes. Prokennalestes gen.n. is congeneric with Prokennalestes Trofimov and Prozalambdalestes Trofimov, which are both nomina nuda.