Orovenator mayorum (Reisz, Modesto and Scott 2011) Early Permian~290 mya, was considered the oldest diapsid after the appearance of Petrolacosaurus and Araeoscelis. Ford and Benson 2018 Here Orovenator considered varanopids to be derived from araeoscelids with Orovenator nesting between them. Here the order is reversed with Orovenator nesting between basal protodiapsids and araeoscelids.

Ford DP and Benson RBJ 2018. A redescription of Orovenator mayorum (Sauropsida, Diapsida) using high-resolution µCT, and the consequences for early amniote phylogeny. Papers in Palaeontology 2018:1–43.

Reisz RR, Modesto SP and Scott DMT 2011. A new Early Permian reptile and its significance in early diapsid evolution. Proceedings of the Royal Society, London B
doi:10.1098/rspb.2011.0439

wiki/Orovenator