How Dinosaurs Evolved the World's Longest Necks While Giraffes Fell Short

Giraffes may have long necks, but theirs are nothing when compared to the ones that dinosaurs possessed millions of years ago. Yet how did these creatures evolve longer necks than any other creature that has ever lived since? New research shows exactly how dinosaurs managed it, and why it hasn't happened again.

The largest creatures to have ever set foot on our planet were the long-necked, long-tailed dinosaurs known as the sauropods. They once roamed the Earth millions of years ago, and included titans such as the Brachiosaurus, Diplodocus and Apatosaurus (once known as the Brontosaurus). As vegetarians, they used their long necks in order to reach and grab food from the tops of trees, though recent research shows that the dinosaurs may have kept their necks low while grazing in order to reduce the energy expenditure needed to pump blood to such heights.

Even so, these necks reached up to 50 feet in length, which is six times longer than the giraffe and at least five times longer than any other animal that has lived on land. Sauropods themselves were enormous, reaching about 10 times the size that elephants do.

The size, while interesting, wasn't nearly as baffling as the dinosaurs' necks. How could they support such a long feature? In order to find that out, scientists analyzed other long-necked creatures and compared the anatomy of sauropods to their nearest living relatives--birds and crocodilians.

What exactly did they find? Michael Taylor and his colleagues discovered that sauropods possessed a number of distinct traits that allowed them to support their long necks. Air actually made up about 60 percent of their necks, with some as light as birds' bones. This allowed the dinosaurs to more easily support the massive size of their necks since they were far lighter than they might have otherwise been. In addition, the muscles, tendons and ligaments were positioned around the neck vertebrae in order to help maximize leverage and make neck movements more efficient.

It wasn't only the features that the dinosaurs' necks possessed that helped them, though. The dinosaurs' massive torsos and four-legged stances also provided a stable platform in order to support their necks. In comparison, giraffes have relatively small torsos, which is why their necks are not nearly as impressive as the dinosaurs', according to Livescience.com. It's also likely that sauropods could also breathe like birds, drawing fresh air through their lungs continuously as opposed to breathing out before having to breathe in to fill their lungs. This may have helped them get vital oxygen down their long necks and to their lungs.

In the future, researchers hope to look at further adaptations that may have allowed the sauropod to have such a long neck. For example, the Apatosaurus had strange neck vertebrae. The adaptation may have occurred when the dinosaurs used their necks in combat between males for females.

The study was published in the journal PeerJ.