Saurischian dinosaur (Herrerasaurus ischigualastensis) skull fossil. Saurischian dinosaur (Herrerasaurus ischigualastensis) skull fossil. Herrerasaurus was a lightly built carnivore that had a long tail and a relatively small head. Adult specimens could have skulls measuring up to 56 centimeters in length and could reach a total body length of up to 6 meters. Notably, Herrerasaurus had a flexible joint in its lower jaw, allowing it to slide back and forth to deliver a powerful grasping bite. It also possessed large, serrated teeth designed for biting and consuming flesh. This fossil dates to the Triassic period, 230 million years ago. Found in Argentina.