Brachiosaur dinosaur. Artwork of a brachiosaur dinosaur walking in a rocky landscape by a river. This dinosaur was one of the largest-ever land animals, weighing up to 90 tonnes and measuring over 20 metres from head to tail. Like all sauropods, the brachiosaurs were herbivorous quadrupeds. Sauropods were present for millions of years, first appearing in the late Triassic period. They were widespread in the Jurassic period, and died out with the rest of the dinosaurs at the end of the Cretaceous period.