Brachiosaurus was one of the largest and most iconic sauropod dinosaurs that lived during the Jurassic period, approximately between 154 and 153 million years ago. Characterized by its long and inclined neck, which allowed it to reach the tops of the tallest trees, Brachiosaurus is known to be one of the largest dinosaurs known, measuring about 75 to 98 feet in length and weighing up to 50 tons.