Araeoscelidia

Araeoscelidia or Araeoscelida is a clade of extinct tetrapods (traditionally classified as diapsid reptiles) superficially resembling lizards, extending from the Late Carboniferous to the Early Permian.

They differ from other, earlier sauropsids by their slender limbs, their elongated tail, and of course by the presence of two temporal openings, the feature defining the diapsid condition.

In Araeoscelis, only the upper temporal opening remains, thus resulting in a derived euryapsid condition.

Araeoscelidia includes well-known genera such as Araeoscelis Williston 1910,[1][2] Petrolacosaurus Lane 1945[3][4] and Spinoaequalis,[5][6] known from virtually complete skeletons.

[16] Araeoscelidia are known from the Late Carboniferous in the United States (Petrolacosaurus, Spinoaequalis) to the Early Permian in France (Aphelosaurus), Germany (Kadaliosaurus) and the United States (Dictybolos, Zarcasaurus, Araeoscelis, Halgaitosaurus[17]).