One of the earliest dinosaurs, Herrerosaurus was a bipedal predator with a long and stiffened tail, three main fingers, two vestigial fingers, and sharp, serrated teeth. Its flexible lower jaw helped to grasp prey. Its long legs and hollow bones suggest it was a fast runner. Bite marks on skulls of these animals show they often battled one another, presumably over food or mates. The earliest forms were small, about 10-feet long; later ones were up to twice that length. This rare dinosaur was discovered in 1991 in the Ischigualasto Formation of Argentina.
References: text is from the park placard with minor edits. Information on “nictating membrane” is from an eponymous Wikipedia article.