With its huge feet, long neck, and fondness for plants, the Diplodocus is perhaps one of history’s greatest vegetarians. But research has found that the ancestors of sauropods may have had a taste for meat.
Scientists examining the teeth of some of the earliest dinosaurs to roam the earth say they’ve found telltale clues about what they ate.
dr Antonio Ballell Mayoral, the lead author of the study from the University of Bristol, said that while omnivores, herbivores and carnivores existed in the Triassic period, their ancestors didn’t necessarily share the same diet.
“The earliest members of the two main lineages of vegetarian dinosaurs were not exclusively herbivores,” he said.
Ballell and colleagues report in the journal Science Advances how they analyzed the teeth of 11 early dinosaurs, including Ngwevu intloko, a long-necked ancestor of the sauropods and Lesothosaurus Diagnosticusan early dinosaur with “bird hips,” both of which lived about 200 million years ago.
“Teeth can give good clues as to what an animal is eating because they are our tools to break down food,” Ballell said.
The team not only studied the shape and function of the dinosaurs’ teeth, but also created computer models of how the stress of biting is distributed to them.
The team then fed the results into machine learning algorithms based on the dental traits and feeding habits of 47 living reptiles, including iguanas, geckos, snakes and crocodiles. This allowed researchers to examine the types of food the early dinosaurs were likely to have eaten.
The results show that Ngwevu intloko and other early relatives of the sauropods were probably herbivores, those who lived even earlier – such as Buriolestes schultziroaming up to 237 million years ago—appear to have been carnivores based on their curved and bladed teeth resembling those of modern-day Komodo dragons, and the way those teeth dealt with feeding-related forces.
It also appears that the ancestors of the avian hipsaurids are known as ornithischians — a largely herbivorous clade that includes horn-faced dinosaurs like Triceratops and armored dinosaurs like Stegosaurus — may also have been familiar with the taste of meat. As the authors note, Lesothosaurus Diagnosticus had teeth that exhibited greater mechanical resistance than those typical of carnivores, suggesting that while it may be herbivorous, it is also omnivorous.
The early dietary diversity of dinosaurs was fundamental to their rise and eventual dominance, as it allowed them to adapt to changing climates and food resources, the researchers wrote.
Ballell said that although the very first dinosaurs were traditionally thought to be carnivores, recent discoveries have called this into question. However, Bristol research suggests that carnivores are likely ancestors.
Prof Steve Brusatte, a paleontologist at the University of Edinburgh who was not involved in the work, described the research as innovative and inspiring.
“We’ve long wondered how the earliest dinosaurs were able to outlast their competitors and sweep the world. This new study uses cutting-edge methods to examine the diets of the oldest dinosaurs in unprecedented detail,” he said.
“It looks like the first dinosaurs were likely carnivores and that different groups of dinosaurs changed their diets over time, and this may have helped drive their diversification,” Brusatte added. “Some of the oldest dinosaurs were already experimenting with a variety of foods and feeding styles, and I’m sure this must have played an important role in dinosaurs being able to fill so many niches and become so successful.”