| Named By: | L. A. Leal, S. A. K. Azevodo, A. A. W. Kellner & A. A. S. da Rosa in 2004 |
| Time Period: | Late Triassic, 225 Ma |
| Location: | Brazil - Caturrita Formation |
| Size: | Estimated about 2.5 meters long |
| Diet: | Herbivore |
| Fossil(s): | Almost complete skull and partial post cranial remains |
| Classification: | | Chordata | Reptilia | Dinosauria | Sauropodomorpha | Plateosauria | Plateosauridae | |
Unaysaurus is a genus of sauropodomorph herbivore dinosaur. Discovered in southern Brazil, in the geopark of paleorrota, in 1998, and announced in a press conference on Thursday, December 3, 2004, it is one of the oldest dinosaurs known. It is closely related to plateosaurid dinosaurs found in Germany, which indicates that it was relatively easy for species to spread across the giant landmass of the time, the supercontinent of Pangaea.
Like most early dinosaurs, Unaysaurus was relatively small, and walked on two legs. It was only 2.5 meters long (8.2 ft), 70 to 80 centimeters tall (2 to 3 ft), and weighed about 70 kilograms (155 lb).
The fossils of Unaysaurus are well preserved. They consist of an almost complete skull, complete with a lower jaw, and partial skeleton with many of the bones still connected to each other in their natural positions. It is one of the most complete dinosaur skeletons (including complete skull) ever recovered in Brazil.