Scleromochlus

Scleromochlus (Greek for "hard fulcrum") is an extinct genus of small avemetatarsalian from the Late Triassic period. A lightly built cursorial animal, its phylogenetic position has been debated; as different analyses have found it to be either the basal-most ornithodiran, the sister-taxon to Pterosauria, or a basal member of Avemetatarsalia that lies outside of Ornithodira.

Description
Scleromochlus is a monotypic genus (single species), which is the type species S. taylori.

Scleromochlus taylori was about 181 mm (about 7.1 inches) long, with long hind legs; it may have been capable of four-legged and two-legged locomotion. Most recent studies about its gait suggest that it engaged in kangaroo- or springhare-like plantigrade hopping;[1][2][3] if Scleromochlus is indeed related to pterosaurs, this may offer insight as to how the latter evolved, since early pterosaurs also show adaptations for saltatorial locomotion.

Its fossils have been found in the Carnian Lossiemouth Sandstone of Scotland. The holotype is BMNH R3556, a partial skeleton preserved as an impression in sandstone; part of the skull and tail are missing.