Learn how to draw a Brachiosaurus in few easy steps. The Brachiosaurus is a member of the dinosaur group and the scientific term for them is Baltithorax. Their Greek name “brachio-saurus” means “arm-lizard” in English, referring to its unusually long arms. The Latin word “alti-thorax” means “tall-chest” in English, because of the great depth of its rib cage. It was the largest of all dinosaurs.