How huge hollow bones helped them grow

A seismosaurus neck reconstructed with hollow bones

Dinosaurs, or more specifically sauropods, had the longest necks of any other creature that has ever lived on Earth. A sauropod could have a neck up to 50 feet long, six times longer than a giraffe’s neck, according to Live Science.

But how did their necks get so long?

Apparently, it had to do with their hollow bones.

In a recent study, led by paleontologist Michael Taylor and published in PeerJ, researchers found that 60 percent of sauropod necks consisted of air, and some necks were just as light as the bones of birds. It also helped that sauropods had large torsos, stood on four legs, and had up to 19 neck vertebrae. Additionally, sauropods had heads so small they were basically just mouths—and they didn’t even have cheeks! Because of this, they didn’t chew their food; they just swallowed it.

One good thing about being built like a bird is it allowed sauropods to continuously “draw fresh air through their lungs,” according to Live Science. This made it much easier to breath than if they had to breathe like mammals, meaning they would have to breathe out before breathing in again.

There are a few reasons why sauropods evolved to have long necks. Maybe they needed a long neck to reach leaves on tall trees, or maybe they swept their neck from side to side to graze on grass. Another theory is that long necks attracted potential mates. In Live Science, Taylor said he and his colleagues suspected that Apatosaurus males combated each other with their necks, probably to fight over females. Apatosaurus apparently had a bifurcated neck that made them extra wide and deep.