Eodromaeus (meaning "dawn runner") is an extinct genus of probable basal theropod dinosaurs from the Late Triassic of Argentina.

Like many other of the earliest-known dinosaurs, it hails from the Carnian-age (~230 Ma) Ischigualasto Formation, within the Ischigualasto-Villa Unión Basin of northwestern Argentina.

Upon its discovery, it was argued to be one of the oldest true theropods, supplanting its contemporary Eoraptor, which was reinterpreted as a basal sauropodomorph.

[1] A press release estimated that its total length reach about 1.2 meters (3.9 feet) from nose to tail, with a weight of about 4.5 to 6.8 kg (9.9 to 15.0 lb).

[4] The animal was lightly built and had long hindlimbs, suggesting that it was well-built for running even by the standards of most early dinosaurs.

The cranium had a relatively low number of knife-shaped teeth (fifteen in total) which were longest in the front half of the maxilla.

[1] The cervicals (neck vertebrae) were significantly more elongated than those of Eoraptor, and those near the shoulders had large pits which would have housed air sacs.

Eoraptor had previously been regarded as a theropod, but Martinez et al. (2011) instead concluded that it likely represented one of the most basal sauropodomorphs, the group that includes animals like Apatosaurus.

[1] There is still a small amount of debate over the position of Eoraptor, with a few studies reclaiming it as a theropod alongside Eodromaeus.

Other putative theropods such as Tawa, Chindesaurus, Daemonosaurus, and herrerasaurids fall even further stemwards than Eodromaeus according to this study and derived works.

[17][18] A subsequent response to that critique, by Baron et al. (2017), placed Eodromaeus as a basal herrerasaurian and simultaneously shifted the entire family Herrerasauridae outside of Dinosauria.