Why Are They All So Big? The Evolution of Giant Sauropod Dinosaurs – Nikkei Science

Of all the animals that once roamed the Earth, sauropods, the famous dinosaurs with long necks and tails, are unique. No other terrestrial animal comes close to its gigantic size. They pale in comparison to all other dinosaurs, including duck-billed hadrosaurs, horned ceratopsians, armored ankylosaurs, and predatory tyrannosaurs. The mightiest land mammals (such as mammoths and rhinos) weigh nearly twice as much as the largest living elephant, but are dwarfed by the largest sauropods.

From an evolutionary perspective, this peculiarity makes sauropods interesting and unusual. In the world of evolution, there are many examples of convergent evolution, where the same characteristics evolve over and over again in different groups of organisms. A classic example of convergent evolution is flapping flight. Wing flapping evolved in birds, bats, pterosaurs and insects, but the bones and other structures that make up wings differ between groups of animals, showing that their evolutionary origins were separate. Convergent evolution is so common in nature that this size, found only in sauropods, is unique in itself. Other terrestrial animals weighed less than a third of the largest sauropods. What made sauropods stand out from the crowd, both literally and figuratively?

Thanks to the discovery of a large number of sauropod fossils over the past 20 years or so, paleontologists have begun to uncover the full answer to this question. Analysis of the growing fossil record is revealing when and where sauropods became gigantic, and it is becoming clear what enabled them to evolve to gigantic sizes several times over the nearly 150 million years that they dominated. While the largest known sauropods are surprisingly gigantic, the newly discovered giant fossil suggests there may be something even bigger yet to be discovered.