Dinosaurs / Triassic / Herrerasaurus
Herrerasaurus
Triassic heh-RARE-uh-SAWR-us, “Herrera's lizard”
Herrerasaurus was one of the earliest predatory dinosaurs, stalking river floodplains in northwestern Argentina approximately 230 million years ago. Reaching up to six metres in length and weighing over two hundred kilograms, it was among the largest predators of its Triassic ecosystem, though still smaller than the giant non-dinosaurian rauisuchians of the time. Herrerasaurus possessed a primitive combination of traits, including only two sacral vertebrae and five fingers on each hand, alongside specialised adaptations such as a flexible hinge in its lower jaw to secure prey. Running swiftly on long hind limbs, it used curved, serrated teeth and sharp hand claws to hunt early synapsids and rhynchosaurs.
It possessed a flexible joint in the middle of its lower jaw that enabled it to grasp wriggling prey firmly.
Where and when
Herrerasaurus lived in the Late Triassic, from 231.4 to 225 million years ago (Carnian age). Its remains come from Argentina, in the Ischigualasto Formation.
The numbers
Length 4.5 m (estimates run from 3 to 6 m). Mass about 250 kg. Hip height about 1.4 m. That is 2.6 human-lengths, or 0.4 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.