Brachiosaurus, brak ee uh SAWR uhs or bray kee uh SAWR uhs, was a gigantic, plant-eating dinosaur that lived about 150 million years ago in what are now Africa and North America. The name Brachiosaurus means arm lizard. Unlike most dinosaurs, Brachiosaurus had arm bones that were longer than its leg bones. These long arm bones placed the shoulders higher than the hips, and so the body sloped down from the base of the neck to the tail.