Sarcodontidae Lopatin and Kondrashov, 2004

Missiaen, Pieter & Smith, Thierry, 2008, The Gashatan (late Paleocene) mammal fauna from Subeng, Inner Mongolia, China, Acta Palaeontologica Polonica 53 (3), pp. 357-378 : 367

Family Sarcodontidae Lopatin and Kondrashov, 2004 new rank

Type genus: Sarcodon Matthew and Granger, 1925 .

Genera included: Carnilestes Wang and Zhai, 1995 ; Hyracolestes Matthew and Granger, 1925 ; Metasarcodon Lopatin, 2006 ; Prosarcodon McKenna, Xue, and Zhou 1984 .

Revised diagnosis.—Small to medium−sized insectivores, characterised by the presence of only two lower and two upper molars with a straight centrocrista, and by a dentition with a carnassial tendency. Incisors small, canines large and caniniform. Premolariform p4, with a relatively strong metaconid and a short talonid with only one cusp. The p4 and lower molars characterised by a high trigonid with a strong paracristid and a weak to absent precingulid. Premolariform P4. Long, prominent metastylar crest on P4 and M1. Postcingulum very small to absent on P4 and M2, but relatively well−developed on M1. Upper molars transversely elongated, with twinned paracone and metacone, and developed conules.

Remarks.—The subfamily Sarcodontinae was named by Lopatin and Kondrashov (2004) to include Sarcodon , Prosarcodon , Metasarcodon , Carnilestes and, tentatively, Hyracolestes . We confirm the inclusion of Hyracolestes in this group, and moreover we elevate Sarcodontinae to family rank. We consider Sarcodontidae a natural group, clearly different from Micropternodontidae with which they were previously allied ( Van Valen 1967; McKenna and Bell 1997). Sarcodontidae are present in Asia from the earliest Paleocene until the middle Eocene, and are characterised by having only two molars and by the absence of a hypocone shelf on P4 and M2. Conversely, Micropternodontidae only appear in the middle Eocene, and have three molars and a hypocone shelf on P4 and the upper molars. After their separation from micropternodontids, we see no reason to continue to place sarcodontids in Soricomorpha . Instead, Sarcodontidae resemble cimolestans such as didymoconids, wyolestids, cimolestids and palaeoryctids, in the large, caniniform canines, in the transversely elongated upper molars with partially fused paracone and metacone, and in the high trigonid on the lower molars. They specifically resemble Didymoconidae in having only two molars. The lower molars of sarcodontids resemble those of Wyolestidae in the anteriorly placed paraconid, and those of Wyolestidae and Cimolestidae in the well−developed talonid cusps. Finally, they also resemble Palaeoryctidae by the strong metastylar crest on the upper cheek teeth, and by basicranial characters already noted by Butler (1988). Based on this, we consider Sarcodontidae as members of Cimolesta , with uncertain ordinal affinities.