Although "brontosaurus" is a better-known name, scientists now refer to this giant, plant-eating dinosaur as an "apatosaurus" because the name was first used to identify the beast, and the first name used holds throughout. They are five-toed, long-necked dinosaurs, who were the dominant herbivores of their time. Stegosaurus is a plated dinosaur that had a blimp-like body, long hind legs, short front legs, and a small head. Its long, heavy tail carried several pairs of long, bony spikes. The midline of its back had two rows of unpaired bony plates. Allosaurus was a large carnivorous dinosaur that had a weight exceeding four tons. It walked on only two legs, using its long, heavy tail for balance.