Eodromaeus

Eodromaeus was a diminutive predatory dinosaur that roamed northwestern Argentina during the Late Triassic, roughly 230 million years ago. 2 metres in length and weighing only about five kilograms, this lithe hunter possessed hollow bones and long, bird-like running legs. Its skull was equipped with curved, serrated teeth suitable for capturing insects and small vertebrates. For years, contemporary Eoraptor was regarded as the definitive basal theropod, but the discovery of Eodromaeus revealed true theropod features, prompting researchers to reclassify Eoraptor as an early sauropodomorph. Eodromaeus therefore represents one of the earliest authentic members of the theropod branch, offering critical clues regarding the ancestral morphology and hunting adaptations that ultimately led to giants like Allosaurus and Tyrannosaurus.

Its discovery helped clarify that Eoraptor was a basal sauropodomorph rather than a theropod.

Where and when

Eodromaeus lived in the Late Triassic, from 231.4 to 228 million years ago (Carnian age). Its remains come from Argentina, in the Ischigualasto Formation.

The numbers

Length 1.4 m (estimates run from 1.2 to 1.5 m). Mass about 4.9 kg. Hip height about 0.45 m. That is 0.8 human-lengths, or 0.13 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Eodromaeus with a bus Place on the timeline