The Aucasaurs is a smaller Theropod that is a primary character in Alpha's Egg.
An Aucasaurs was one of the top predators in South America next to Giganotosaurs, Mapusaurus, and Tyrannotitan. Similar to other predators it had large jaws capable of killing other dinosaurs. Interestingly Aucasaurus had very short arms that are deemed useless.
During the episode listed above, Dragonfly, is one of the main characters of the episode. During said episode he meets Alpha a female Saltasaurus multiple times during their lives. After growing up, Dragon procedes to leave his family and start his own. Culminating in a final battle between Alpha and the two. Ultimately Dragonfly's skull is crushed underneath her weight.