Eucritta melanolimnetes (Clack 1998, 2007; Viséan, Early Carboniferous, 340 mya; ~25cm in length) was originally considered a loxomatid amphibian, due to keyhole shaped orbits (I don't see them here). Eucritta nests as a basal reptilomorph between Eoherpeton and Seymouriamorpha, like Kotlassia and Utegenia.
Five specimens are known. Another skull is shown below. Eucritta grew isometrically wth greater ossification in larger specimens, including longer ribs.