[MM] Sinodelphys szalayi
DESCRIBER Luo, Ji, Wible & Yuan, 2003
TIME Cretaceous Early
FOSSILSITE Yixian Formation, Liaoning Province, China
Sinodelphys szalayi gen. et sp. nov. is distinguishable from all mammals previously known from the Yixian Formation [125 million years ago (Ma)] by a long list of apomorphies. Numerous dental and skeletal apomorphies also distinguish Sinodelphys from all Cretaceous eutherians (including Eomaia from the Yixian Formation). Sinodelphys is also more derived than the stem boreosphenidans outside the therian crown group (metatherians eutherians) in several dental apomorphies, but is less advanced than other metatherians including Deltatheridium in dental formula. Hairs are preserved as carbonized filaments and impressions around the torso of the holotype. The pelage appears to have both guard hairs and denser underhairs close to the body surface.