In 1959, the remains of a Herrerasaurus—thought by some paleontologists to be the second oldest known dinosaur—was discovered in Argentina. It was found in a layer of rock known as the Ischigualasto formation; the area is located in the Ischigualasto Valley, or the “Valley of the Moon.” The discoverers were a goat herder named Victorino Herrera and paleontologist Osvaldo Reig. In 1988, a complete skull and skeleton of Herrerasaurus was found in the same area by Paul Sereno and Fernando Novas. This 10-to 20-foot (3-to 6-meter) reptile had numerous characteristics enabling it to succeed at its carnivorous lifestyle, such as recurved teeth, powerful hind limbs, a bipedal stance, and strong arms. It was excavated from rock laid down during the beginning of the Late Triassic period, approximately 230 million years ago.