Vaughnictis smithae (formerly Mycterosaurus smithae; Lewis and Vaughn 1965, Brocklehurst et al. 2016; early Permian, MCZ 2985) was originally considered a species of Mycterosaurus, then a sister to Eothyris. In the large reptile tree it nests as the last common ancestor to all synapsids and diapsids, derived from Protorothyris. It is the most primitive taxon in this clade with a lateral temporal fenestra. The fang set is reduced to a single fang. The orbit rises slightly above the rostrum. The palate (see below) is the most complex among tetrapods, which sets Vaughnictis apart from the more plesiomorphic hypothetical ancestor — with the side note that we don't have palate data for the sister taxa shown above.