Staurikosaurus

Staurikosaurus is a genus of Upper Triassic theropod dinosaurs found in Brazil. It was a small, lightly built carnivore.
The rarity of "Staurikosaurus" remains may be a result of it being uncommon while alive, or because it lived in an environment such as a forest, where fossils rarely form.
Description.
At just , 80 centimetres tall (31 in), and weighing just 30 kilograms (66 lb), "Staurikosaurus" was small in comparison to later theropods like "Megalosaurus". "Staurikosaurus" and the related "Herrerasaurus" are definitely theropods and evolved after the sauropod line had split from the theropods.
The fossil record of "Staurikosaurus" is poor, but the skeletal structure of the legs is known. "Staurikosaurus" was a quick runner for its size. It also had just two vertebrae joining the pelvis to the spine, a distinctly primitive arrangement.
The available teeth for Staurikosaurus strongly suggest a carnivorous diet.
Tail.
The tail of "Staurikosaurus" was relatively long (with more than 40 vertebrae) compared to the rest of its body and was held straight and off the ground as it ran. The rear part of "Staurikosauruss tail is stiffened by features of the tail vertebrae. Ostrom thought this was a dynamic stabilizer to help balance while leaping and running.