Why Sauropods Grew So Huge

About this drawing

A giant brachiosaurus raises a great question: how could anything on land get that big? Sauropods, the group it belongs to, were the largest animals ever to walk the Earth. No land mammal has come anywhere close to their size, and the African elephant looks small by comparison.

Part of the answer lies in what they didn't do, which is chew. Because they swallowed plants almost whole, their heads could stay small and light, and that made a very long neck possible. With that reach, they could graze a huge area without moving their bodies, saving a ton of energy.

Breathing helped as well. They had a bird-style system of air sacs that worked better than mammal lungs, and the same system lightened the skeleton by filling bones with air pockets. Without that weight savings, their legs would have had a much harder job.

Reproduction played a part, too. Sauropods laid many eggs, and the young grew fast, so populations could bounce back from heavy losses among hatchlings. An elephant, on the other hand, has one calf after a very long pregnancy. Add in warm Jurassic weather and lots of plants, and you get a combination that nature has never repeated.

• dinosaurs
• brachiosaurus
• giants
• adult coloring