An Ancient Mystery in Every Step
For decades, paleontologists puzzled over how sauropods—some of the largest land animals to ever live—managed to circulate blood up their towering necks. With some species like Mamenchisaurus sporting necks up to 40 feet long, the challenge was clear: how did blood make the long journey to the brain without modern-day circulatory shortcuts?
The solution may not have been in their hearts at all—but in the neck itself. New findings suggest the motion of walking dinosaurs provided a mechanical boost to blood flow, thanks to specialized anatomy that made their necks more than just long.
The Discovery in the Desert
Michael Habib, a paleontologist at the University of Southern California, began exploring this idea after examining the fossilized neck of a giant titanosaur found in New Mexico. The bones included extremely long cervical ribs—bony rods nearly six feet in length.
Unlike rigid bones, these structures were made of a flexible material. Habib compared them to biological springs. As the dinosaur walked, its long neck risked swaying uncontrollably. But the cervical ribs acted as shock absorbers, steadying the massive structure with each step.
A Built-In Blood Booster
Habib proposed a second, more surprising function for these springy bones. Based on the arrangement of known muscles, blood vessels, and air sacs in both fossils and living animals, he suggested that the flexing of the cervical ribs compressed muscles and air sacs around the main artery.
This movement may have acted like a secondary pump. Each stride helped squeeze blood upward through the neck, easing the workload on the heart. Habib presented this hypothesis at the Society of Vertebrate Paleontology meeting in Dallas, Texas.
From Theory to Function
Previous theories to explain blood flow in sauropods included massive two-ton hearts and complex siphon systems, but none were supported by fossil evidence. Habib’s model relies on only the preserved bones and the expected anatomy surrounding them. Even a small contribution from neck motion—just one to three percent of muscle force—could have reduced the necessary heart size by more than a quarter.
The longer the neck, the more muscle, and the stronger the pumping effect. This could explain how extreme-necked dinosaurs managed circulation without needing unpreserved organs. As Habib put it, the neck itself did part of the work: it paid for itself with every move.
Some dinosaurs had necks so long it raised a question no one could ignore—how did they get blood all the way to their brains?
With some sauropods stretching over 40 feet (12 meters), their anatomy held a secret that might explain how nature solved a colossal problem…🧵👇 pic.twitter.com/23nGTDAZyt
— Detective Tiger's Stories (@TigerDetective) June 5, 2025