Brachiosaurus was one of the largest and heaviest dinosaurs that ever lived. The top of a man’s head would have reached only to this giant creature’s knees. It had a huge body, a very long neck, a small head and a long tail.
The best-known Brachiosaurus skeleton in the world is now thought to be a different genus – Giraffatitan. However, an even bigger animal, Ultrasauros, found in the Dry Mesa Quarry in Colorado, is now regarded as a particularly big specimen of Brachiosaurus. The original Brachiosaurus was discovered as two partial skeletons in the Morrison Formation near Fruita in Utah in 1900 by Elmer G. Riggs.
Name: Brachiosaurus, meaning ‘tall-chested arm lizard’
Size: up to 23m long and 12m high
Food: leaves and shoots of trees
Lived: about 152-145 million years ago in the Late Jurassic Period in western North America
About half of the height of Brachiosaurus is due to the neck. This, with its long front legs and tall shoulders, meant that it could reach high up into the trees to feed. Even its front feet contributed to its high reach – the fingers are arranged long and pillar-like, and arranged vertically in the hand. Despite its fame, it is one of the rarest of the sauropods of the Morrison Formation.
A large, powerful heart pumped blood all the way up Brachiosaurus’ neck to its small brain. Some scientists believed it may have even have had several hearts to pump the blood around its massive body. Strong muscles along the neck bones helped to hold up its head. Unlike most dinosaurs, Brachiosaurus’ front legs were longer than its back legs. These helped to support the weight of its long neck.
Brachiosaurus browsed among the treetops that were out of reach for other herbivores. Using its long neck, it could pluck the highest leaves, in the same way that giraffes feed today. Brachiosaurus had strong jaws with teeth shaped rather like sharp-edged spoons for nipping off shoots and twigs. The position of the neck – whether it was vertical or horizontal – is an ongoing debate among scientists.
Brachiosaurus’ legs ended in short, thick toes. Underneath the bones of each foot was a pad which cushioned the legs against the jarring shock of its weight. Brachiosaurus held its legs straight underneath its body. This helped to support its enormous body weight. Elephants also hold their legs very straight beneath their bodies.
Brachiosaurus needed to eat an enormous amount to supply enough energy for its huge body to grow and move about. An elephant eats about 150kg of food a day. Brachiosaurus may have eaten as much as 1500kg of food a day – ten times as much as the average elephant. It probably travelled in herds and roamed over large areas of land each day to find fresh trees.
Because Brachiosaurus was so heavy, scientists once thought that it lived in lakes and rivers, where the water would support its massive weight. They believed that its legs would sink deep into the ground as it walked on land. Its nostrils were on the top of its head so it could probably keep its head above the water to breathe. In the water, Brachiosaurus would be safe from attack by fierce carnivores.
Nowadays however, scientists believe that Brachiosaurus lived only on land. The pressure of the water would have crushed its ribs, squashing its lungs. We now know, too, thats its legs were strong enough to carry the weight of its body as it lumbered through forests, along rivers and around lakes.