Unaysaurus, meaning “black water lizard,” is a genus of sauropodomorph dinosaur from the Carnian to Norian ages of the Late Triassic Period (225 to 200 million years ago). It was discovered in southern Brazil, which at that time was connected to northwest Africa. During the reign of Unaysaurus, the world was united as the supercontinent Pangaea, which was just starting to break up into the Laurasia and Gondwana continents.
The type species, U. tolentinoi, was named after Tolentino Marafiga, who discovered the fossils by the side of a road in 1998. The new species was officially described and published in the Oct 18, 2004 issue of the scientific journal Zootaxa.
Marafiga found the fossils in the southern Brazilian state of Rio Grande do Sul, near Santa Maria. It was recovered from the Caturrita Formation. The oldest dinosaurs in the world have been found in this area and in nearby Argentina, suggested that the first dinosaurs may have originated from this area.
Unaysaurus was the first prosauropod discovered in Brazil. Prosauropods were semi-bipedal, herbivorous dinosaurs that are related to the later and more advanced sauropods, which include some of the largest creatures ever to walk the Earth, like Brachiosaurus.
Though Unaysaurus is among the oldest dinosaur fossils in the world is similar to others found in the area, its closest relative is not from South America at all. It is most closely related to the Plateosaurus, which lived about 210 million years ago in Germany. These findings indicates these species were able to migrate easily across the continent Pangaea.
Unaysaurus was relatively small and walked on two legs. It stood about 2 to 3 feet tall and was about 8.2 feet long. It weighed approximately 155 pounds.
Unaysaurus fossils are well preserved. They consist of an nearly complete skull, complete with lower jaw, and a partial skeleton with many bones still connected to each other in their natural positions. It is one of the most complete dinosaur skeletons, and the most complete skull, ever recovered in Brazil.