Supersaurus lived about 155 to 145 million years ago, during the late Jurassic period. Its name means “super lizard”. And it was! Supersaurus is one of the longest and largest land animals ever discovered. It was first found in 1972. Before it was discovered, people believed that Apatosaurus was the largest of the sauropods. But Supersaurus was even bigger. It was a huge dinosaur with a long neck and a long, whip-like tail. It grew to be about 138 feet long and 54 feet tall. This is about the size of an airplane. Its neck was about 40 feet long. It may have weighed up to 55 tons. Its front legs were shorter than its back legs. This meant that it kept its head close to the ground to look for plants that didn’t grow very tall. Because of the big bones in its neck, it might not have been able to move its head very easily. All its legs had elephant-like feet, with five toes and fleshy pads to protect them. One toe on each foot had a thumb claw. This was probably used for protection against hunting carnivores. It may also have used its tail to whip predators away.
Supersaurus lived in the forests. It was an herbivore, meaning that it ate only plants. It had to eat lots and lots of plants every day – about 300 pounds - to keep itself alive! It used its small, blunt teeth to rip leaves off plants. It mainly ate conifers, but it also ate the leaves from gingko trees, ferns, cycads, mosses and horsetails. Like many huge sauropod dinosaurs, Supersaurus swallowed leaves whole, without chewing them. It didn’t have cheeks or grinding back teeth, which a dinosaur needs for chewing. Instead, it swallowed small stones called gastroliths. These stones stayed in the creature’s gizzard to grind the tough plant leaves into mush. When the food was soft enough, it would move on to the stomach where it could be digested.
Supersaurus moved slowly on four legs and might have walked in herds, or large groups. If one Supersaurus can eat so much in one day, imagine how much an entire herd of these dinosaurs would eat! Once a herd of Supersaurus had eaten all the food in one area, they would migrate – or move – together as a group to a new area. Baby Supersaurus hatched from eggs like all other dinosaurs. Their eggs have been found in lines along the ground. This means that mothers probably laid their eggs while they were walking. They did not look after the eggs once they were laid. The babies had to fend for themselves after they hatched. If they survived, a Supersaurus could live to be 100 years old. It had a small brain compared to its huge body. It was not a very intelligent dinosaur. We know this by studying this creature’s skull: the smaller the space in its skull, the smaller the brain! The first Supersaurus fossil was found in western Colorado, North America. We don’t know very much about this dinosaur because only one Supersaurus skeleton has ever been found, and it is not complete. Two shoulder bones, ribs, neck vertebrae (which are the bones in its neck), and a hip bone are all that have been found.