Sanjuansaurus

Sanjuansaurus was an early carnivorous dinosaur found in the famed Ischigualasto Formation of San Juan Province, Argentina. Known from a partial skeleton that includes jaw fragments, vertebrae, pelvic bones, and limbs, it belongs to the herrerasaurids, one of the earliest clades in dinosaur history. In life, Sanjuansaurus measured around three metres in length, comparable in size and general proportions to its close contemporary Herrerasaurus. It moved bipedally on sturdy hind legs and possessed robust forelimbs fitted with sharp claws for grappling prey. Its pointed, recurved teeth indicate an exclusively carnivorous lifestyle, feeding upon small to medium-sized reptiles such as cynodonts and rhynchosaurs. The discovery of Sanjuansaurus demonstrated that herrerasaurid dinosaurs were more diverse than previously thought, successfully coexisting as top terrestrial predators within the lush river valleys of Late Triassic South America.

It was discovered in the same rocks as Herrerasaurus, proving two distinct herrerasaurid species shared the ecosystem.

Where and when

Sanjuansaurus 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 3 m (estimates run from 2.8 to 3.2 m). Mass about 61 kg. Hip height about 0.9 m. That is 1.8 human-lengths, or 0.27 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Sanjuansaurus with a bus Place on the timeline