The popular conception of dinosaurs is one of hugeness. But dinosaurs came in all sizes, and shapes were extremely diverse, much like today’s birds. They ranged in size from the gigantic sauropods, like Brachiosaurus, to small, chicken-sized ones like Compsognathus, and every size in between. Because we have found relatively few fossils—compared to how many dinosaurs scientists believed once inhabited Earth—it is hard to give an “average” size for dinosaurs.