Want to learn how to draw a Allosaurus in few easy steps. The Allosaurus is a member of the dinosaur group and the scientific term for them is A. fragilis. Their Greek name “allo-saurus” means “different-lizard” in English. The Latin word “fragilis” means “fragile” in English, because this animal possessed delicate framework in its skeleton. Despite this disadvantage, the large two-legged predators were therefore not too heavy for running quickly. Another aspect that contributed to its lightweight body was small arms, but the tail was very large for maintaining balance.