How Dinosaurs Evolved the Longest Necks

By Samba Lampich

The discovery of sauropods, or longnecked dinosaurs, created excitement and wonder in the scientific world.  How and why did these gigantic creatures develop necks as long as 50 feet (six times longer than the giraffe)? Some scientists believe that sauropods, which were herbivores, evolved long necks in order to nibble on ground plants, but others believe they grazed on tall trees.

It's All Relative 

Michael Taylor, a vertebrate paleontologist at the University of Bristol in England, and his colleagues analyzed other long-necked creatures that were close relatives—birds and crocodilians. The secret, the researchers concluded, was that sauropods had mostly hollow neck bones.

“Extinct animals — and living animals, too, for that matter — are much more amazing than we realize,” Taylor told LiveScience. “Time and again, people have proposed limits to possible animal sizes, like the five-meter (16-foot) wingspan that was supposed to be the limit for flying animals. And time and again, they’ve been blown away. We now know of flying pterosaurs with 10-meter (33-foot) wingspans. And these extremes are achieved by a startling array of anatomical innovations.”

Adaptating To Support A Long Neck

Taylor and his team of paleontologists found that several adaptations supported long necks. Most notable was that sauropods’ necks were made up of 60 percent air with some as light as bird bones. Taylor believes that these lightweight bones made it easier for sauropods’ bodies to support long necks, and therefore to grow longer over time.

The positioning of the muscles, tendons and ligaments around the vertebrae was also significant in that it maximized leverage and allowed the dinosaurs to swivel their necks to eat what they needed before moving their massive bodies. Sauropods also had up to 19 neck vertebrae in contrast to the 7 vertebrae of nearly all mammals, which limit how long their necks can grow.

Sauropods also had small heads with no cheeks not clear how their swallowing and chewing is relevant. These small heads could be supported easily by long necks. In addition, the dinosaurs’ giant torsos and four-legged stances helped provide a stable platform for their necks.

Differing Conclusions

But Matthew Cobley, a paleontologist at the University of Utah, isn’t convinced that sauropods had flexible necks. Looking at the ostrich, Cobley found that cartilage and soft tissue reduced ostriches’ flexibility to the extent that dinosaurs wouldn’t have been able to swivel their heads to feed. However, ostriches may not be an ideal analogy because, unlike sauropods or giraffes, they walk on two legs. Further research would be needed to firmly conclude not just how — but also why — sauropods evolved to have such long necks.