Dinosaurs had more diversity, new study says

There’s more than one way to supersize a dinosaur. Scientists studying the ancient bones of sauropod relatives that walked the Earth more than 200 million years ago have found that they grew to multiton masses 30 million years before the appearance of their cousins, the titanosaurs.

The findings described in the journal Nature Ecology & Evolution could fill in a more complex portrait of the ecology of early dinosaurs and the evolution of sauropods and their relatives.

Think of a sauropod, and a species like Brachiosaurus may come to mind: Long-necked, longtailed, straight-legged with giant bodies and small heads. They arose from the sauropodomorphs, whose members included “the largest animals recorded in the history of life,” the study authors wrote.

Brachiosaurus, which plodded across the terrain 150 million years ago, could outweigh several elephants.

But the ancestors of these titans were different: they were small, nimble and walked on two leg.

In order to grow into massive eusauropoda, or “true sauropods,” these animals had to undergo some major modifications to their body plan, scientists say.

But there isn’t a lot of evidence to show what that transition looked like.

“It was long believed that acquisition of giant body size in this clade (over 10 tonnes) occurred during the Jurassic and was linked to numerous skeletal modifications present in Eusauropoda,” the study authors wrote.

A tonne is a metric ton, or 1.1 U.S. tons.

But two strange-looking sauropodomorphs offer a surprising twist to the story of gigantism in these iconic dinosaurs. Cecilia Apaldetti of the National University of San Juan in Argentina and her colleagues examined a new species, Ingentia prima, as well as a previously known species called Lessemsaurus sauropoides.

These so-called lessemsaurids lived 237 million to 201 million years ago, 47 million years before Brachiosaurus did, and yet they had already managed to grow to gigantic sizes — that is, 8 to 11 tons, about the size of a large elephant.

These animals didn’t just grow to massive sizes roughly 30 million years before true sauropods did — they also managed this feat with unexpected adaptations. Their legs were more bent rather than trunk-like, in spite of this great mass. And instead of growing continuously, they grew in short, intense bursts.

“That’s one freaky-looking animal,” said Matthew Lamanna, a dinosaur paleontologist who was not involved in the study.

The idea that such large dinosaurs developed so soon after the emergence of dinosaurs as a group 245 million years ago was also something of a surprise, he added.