Staurikosaurus, meaning “Southern Cross lizard,” is a genus of dinosaur from the Carnian age of the Late Triassic Period (225 million years ago). The first known specimen was recovered from the paleontological site Jazigo Cinco of the Santa Maria Formation, in Rio Grande do Sul, Brazil. The genus name refers to the star constellation, “The Southern Cross,” pictured in the coat of arms of Brazil, which is only visible in the southern hemisphere. In 1970, when Staurikosaurus was first described, it was unusual to find dinosaurs in the southern hemisphere.
The specific name, S. pricei, honors the Brazilian paleontologist Llewellyn Ivor Price. It was described by Edwin Harris Colbert, working at the American Museum of Natural History. Remains of Staurikosaurus are rare, possibly because it may have been uncommon while alive, or maybe because it lived in an environment like a forest, where fossils are rarely found. It is also one of the earliest dinosaurs known.
At 6.5 feet in length, 2.5 feet tall, and weighing 66 pounds, Staurikosaurus was very small in comparison to later theropod like Megalosaurus. Further research confirms that Staurikosaurus and its relatives — Eoraptor and Herrerasaurus — are definite theropod and evolved after the sauropod line had split form Theropoda.
Although very little fossil material of Staurikosaurus is known, dating from such an early period in the dinosaurs’ history and being otherwise so primitive, most of Staurikosaurus’ features can be reconstructed. For example, it is usually depicted with five toes and five fingers — very simple features of an unspecialized dinosaur.
However, since the skeletal structure of the legs is known, it can be seen that Staurikosaurus was a quick runner for its size. It also had two vertebrae joining the pelvis to the spine, a uniquely primitive arrangement. The tail was long and thin and used for balance. Later sauropod had larger, shorter tails relative to their weight.