SKULL OF A NEW MESONYCHID (MAMMALIA, MESONYCHIA) FROM THE LATE PALEOCENE OF CHINA

Cranial remains of Mesonychidae are poorly known from the Paleocene of Asia. A well-preserved late Paleocene mesonychid skull from Anhui Pro vince in China is described here as a new genus and species, Sinonyx j iashanensis. The new species has a primitive dental formula of 3.1.4.3 /3.1.4.3 and distinctive cheek teeth; P3 is three-rooted, P4 lacks a m etacone, the buccal cingula are distinct on P4-M3, M3 lacks a metastyl e, the talonid of p3-4 is trenchant and square-shaped, and m1 and m3 l ack a metaconid. Resemblances of the new genus to Ankalagon, together with the common presence of Dissacus on both continents, suggest that North America and Asia shared a common mesonychid fauna during the lat e Paleocene. Comparison of the new skull to Hapalodectes supports remo val of Hapalodectinae from Mesonychidae, and suggests that mesonychids are closer to archaeocetes than either is to hapalodectids.