Romeriscus perialllus (Baird and Carroll 1967, Early Pennsylvanian (Westphalian A, 306 mya, YPM-PU16 482) was originally considered a limnoscelid reptile and the earliest and most primitive reptile known in 1967. Laurin and Reisz (1992) considered it a tetrapod of unknown affinity and they considered limnoscelids as anamniotes. They were unable to distinguish the various skull elements, but reinerpreted several of the interpretations of Baird and Carroll.
Using DGS I was able to identify most of the bones on the plate. In the large reptile tree this reconstruction nests with Gephyrostegus watsoni.
Distinct from G. watsoni, Romeriscus was twice as large overall and with a more erect occiput. The orbit was 2x longer than tall. The naris was larger. The fore and hind limbs were similar in size. The frontals were wider and the parietals were narrower. The hind limb was narrower than the forelimb.