With its huge feet, long neck and penchant for plants, the diplodocus may be one of history’s biggest vegetarians. But research has revealed the sauropod’s ancestors may have had a taste for flesh.
Scientists studying the teeth of some of the earliest dinosaurs to roam the Earth say they have uncovered telltale clues as to what they ate.
Dr Antonio Ballell Mayoral, the lead author of the research from the University of Bristol, said that while omnivores, herbivores and carnivores all existed by the Triassic period, their predecessors did not necessarily share the same diets.
“The earliest members of the two main veggie dinosaur lineages were not exclusively herbivorous,” he said.
Writing in the journal Science Advances, Ballell and colleagues report how they analysed the teeth of 11 early dinosaurs including Ngwevu intloko, a long-necked ancestor of sauropods, and Lesothosaurus diagnosticus, an early “bird-hipped” dinosaur, both of which lived about 200m years ago.
“Teeth can give good clues about what an animal eats because they are our tools to break down food,” said Ballell.
As well as looking at the shape and function of the dinosaurs’ teeth, the team made computer models of how stress would be distributed across them when biting.
The team then fed the results into machine-learning algorithms based on the dental features and diets of 47 living reptiles such as iguanas, geckoes, snakes and crocodiles. This allowed the researchers to investigate the types of food that the early dinosaurs were likely to have tucked into.
The results reveal that while Ngwevu intloko and other early relatives of sauropods were likely to have been herbivores, those that lived even earlier – such as Buriolestes schultzi, which roamed up to 237m years ago – appear to have been carnivores based on their curved and bladed teeth, similar to those of today’s Komodo dragon, together with how these teeth handled feeding-related forces.
It also seems that the ancestors of the bird-hipped dinosaurs known as ornithischians – a largely plant-eating group that includes horn-faced dinosaurs such as triceratops and armoured dinosaurs such as stegosaurus – might also have been familiar with the taste of meat. As the authors note, Lesothosaurus diagnosticus had teeth that had greater mechanical resistance than those typical of carnivores, suggesting that while it could have been a herbivore it is also possible it was an omnivore.
The early dietary diversity of dinosaurs was fundamental in their rise and later dominance, allowing them to adapt to changing climates and food resources, wrote the researchers.
Ballell said that while it had traditionally been thought the very earliest dinosaurs were carnivorous, more recent discoveries challenged this. However, the Bristol research suggests carnivory is likely to be ancestral.
Prof Steve Brusatte, a palaeontologist 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 around the world. This new study uses cutting-edge methods to study the diets of the oldest dinosaurs in never-before-seen detail,” he said.
“It looks like the first dinosaurs were probably meat-eaters, 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 already were experimenting with a wide variety of foods and feeding styles, and I am sure this must have played an important role in helping dinosaurs fill so many niches and become so successful.”