Earliest eutherian mammal skull, from the Late Cretaceous (Coniacian) of Uzbekistan

We describe a partially crushed skull and dentaries of a sub-adult individu al of Daulestes nessovi sp. n., from the Coniacian of Uzbekistan. This is t he earliest known eutherian skull (about 87 Ma) and the sixth genus of Cret aceous eutherians in which a skull is available. Because the skull of D. ne ssovi is sub-adult, certain plesiomorphic features may be ontogenetic and s hould be interpreted with caution. Four upper premolars and five lower prem olariform teeth were in use (possibly to become four lowers when fully adul t). The upper cheek-teeth have winged conules; M2 has large parastylar and small metastylar projections. Pre- and postcingula are lacking on DP4 and t he upper molars. The talonids of dp4-m2 are about 90% as wide as the trigon ids, with widely separated entoconid and hypoconulid. The skull has a large sphenorbital fissure, no foramen rotundum, and apparently no pterygoid pro cess of the sphenoid. A large orbital wing of the palatine prevents maxilla -frontal contact within the orbit. The zygomatic arch is slender. The cochl ea has one full turn, with an expanded apex, which suggests that a lagena m ight have been present. A large malleus with a robust anterior process, and a large promontorium may be due to young age of the individual or a primit ive retention, as in the platypus. Because of the similarity to Asioryctida e in both cranial structure and dentition, we assign Daulestes tentatively to Asioryctitheria Novacek et al. 1997, family incertae sedis.