Lagerpetidae

Lagerpetidae (/ˌlæɡərˈpɛtɪdeɪ/; originally Lagerpetonidae) is a family of basal avemetatarsalians (early-diverging members of the reptile lineage leading to birds and other dinosaurs). Though traditionally considered the earliest-diverging dinosauromorphs (archosaurs closer to dinosaurs than to pterosaurs), fossils described in 2020 suggested that lagerpetids are instead an early branch of pterosauromorphs (closer to pterosaurs than to dinosaurs). Lagerpetid fossils are known from the Triassic of San Juan (Argentina), Arizona, New Mexico, and Texas (United States), Rio Grande do Sul (Brazil), and Madagascar. Scleromochlus, a minuscule archosaur from Scotland, is sometimes regarded as a lagerpetid or close relative of the family.

Lagerpetids were generally small and lightly-built animals; the largest include Dromomeron gigas (from Argentina) and an indeterminate Dromomeron specimen from the Santa Rosa Formation of Texas, reaching a femoral length of 15–22 cm (5.9–8.7 in). Lagerpetid fossils are rare; the most common finds are bones of the hindlimbs, which have a number of distinctive features. Remains from other parts of the body have accumulated more frequently since the late 2010s. Several species are now known to possess both small densely-backed teeth and a toothless beak at the tip of the snout.