Yanoconodon alllini (Luo, Chen, Li and Chen 2007; Early Cretaceous, 122 mya; 13 cm in length) is known from a nearly complete and articulated crushed fossil and is traditionally considered a eutriconodont. That clade is paraphyletic in the large reptile tree. Here Yanoconodon was derived from a sister to Pachygenelus and a sister gave rise to the clade Mammalia, with the egg-laying Monotremata as the proximal descendant clade.

Yanoconodon had a semi-sprawling posture and a a long, robust torso with thick lumbar vetebrae with very short ribs. The limbs were short. The canines were quite narrow. The posterior jaw bones were still attached to the jaw. They had not yet become reduced to middle ear bones.