Brachiosaurus was one of the tallest and largest dinosaurs ever discovered. It lived during the middle to late Jurassic period, about 156 to 145 million years ago. It had a long neck, a small head and a short tail for its huge body. Like all the other sauropods, Brachiosaurus walked on four legs. Unlike most dinosaurs, its front legs were longer than its hind legs: this, together with its very long neck, made Brachiosaurus look a little like a giraffe. It also made it very tall. Brachiosaurus grew up to 85 feet tall and weighed about 70 tons. Each foot had five toes and thick pads. It had a claw on the first toe of each front foot and claws on the first three toes of each rear foot. Brachiosaurus had very large nostrils on the top of its head. Some paleontologists believe that it lived in the water and could breathe with its head underwater. But most believe that it just had a good sense of smell.
Brachiosaurus was an herbivore, meaning that it only ate plants. It probably ate the tops of tall trees with its large chisel-shaped teeth. It swallowed its food whole, without chewing it. Brachiosaurus was always looking for food. It would have needed about 400 pounds of food a day to stay alive! Like many large sauropods, Brachiosaurus swallowed small stones with its food. These stones were called gastroliths. The gastroliths went to the creature’s gizzard, where they mashed the tough plant food into mush. Then the food would pass on to the stomach where it was digested. Brachiosaurus probably traveled in large groups or herds. Once they ate all the food in one place, the entire group would move to another place, many miles away. When they were on the move, the larger, stronger adults walked along the edges of the group. The young stayed in the center to be protected against predators.
The best defense this dinosaur had was its size. It was so big that most carnivores stayed far away. It also had a thick tail that could whip away most big hunters. Brachiosaurus had leathery skin that was difficult to bite through. Brachiosaurus hatched from eggs, like all other dinosaurs. Their eggs have been found in a straight line along the ground. This might have meant that these creatures laid their eggs as they were walking and not in nests as many other dinosaurs did. Sauropod dinosaurs did not take care of their babies after they hatched. The babies were left to fend for themselves. They had clawed feet to help them protect themselves. Their eggs were very small compared to the large size of the adults. A baby Brachiosaurus would have been no larger than a cat, and would have grown quickly after that. After 12 years or so, it would be as large as its parents. As adults, they might have lived to be 100 years old! Many Brachiosaurus fossils have been found in Tanzania, Africa. They have also been found in many other places in Africa and North America.