Scientists discover what was on the menu of the first dinosaurs

According to a team of paleobiologists from the University of Bristol, the earliest dinosaurs included carnivorous, omnivorous, and herbivorous species.

By looking at the tooth shapes of the earliest dinosaurs and simulating their tooth function with computer models, experts were able to compare them to living reptiles and their diets. Their findings, published December 16 in scientific advances, show that many groups of herbivorous dinosaurs were omnivores by nature, and that the ancestors of our famous long-necked herbivores like Diplodocus ate meat. This ability to diversify their diet early in their evolution likely explains their evolutionary and ecological success.

The earliest dinosaurs are puzzling: they were much smaller than their later relatives and were overshadowed by crocodile-like reptiles for most of the Triassic. It is unknown how diverse they were in terms of diet and ecology, but scientists do know that something must have happened in the Triassic that allowed dinosaurs to survive and adapt to the aftermath of the Triassic-Jurassic mass extinction event to become the dominant group for the remainder of the Mesozoic period.

lead author dr Antonio Ballell of the University of Bristol said: “Dinosaurs exhibit an interesting variety of skull and tooth shapes soon after they are formed. This has led paleontologists to suspect for decades that different species were already experimenting with different species, comparing them to modern species of lizards and trying to deduce what they were eating from the similarities in their teeth.

“We investigated this by using a range of computational methods to quantify the shape and function of early dinosaur teeth and comparing them to living reptiles, which feed differently. This included mathematically modeling their tooth shapes and simulating their mechanical responses to biting forces using engineering software.”

Professor Mike Benton, co-author of the study, said: “Using this set of methods, we were able to numerically quantify how similar early dinosaurs were to modern animals, providing solid evidence for our dietary conclusions. Theropod dinosaurs have pointed, curved, and blade-like teeth with tiny prongs that behaved like those of modern monitor lizards. In contrast, the serrated teeth of ornithischians and sauropodomorphs more closely resemble modern omnivores and herbivores such as iguanas.

The study is also innovative in using machine learning models to classify the earliest dinosaurs into different dietary categories based on their tooth shape and mechanics. For example, Thecodontosaurus, the Bristol dinosaur, had teeth that were well-adapted to a plant-based diet.

Professor Emily Rayfield, senior co-author, said: “Our analyzes show that ornithischians – the group that includes many herbivorous species such as the horned dinosaurs, armored ankylosaurs and duckbilled dinosaurs – started out as omnivores. Another interesting discovery is that the earliest sauropodomorphs, ancestors of long-necked vegetarian sauropods like Diplodocus, were carnivores. This shows that neither of these two lineages were ancestral to herbivores, contradicting traditional hypotheses, and that the diets of early dinosaurs varied widely was. “

dr Ballell concluded: “It appears that one of the things that made the first dinosaurs so special is that they evolved different diets during the Triassic, and we think this may have been key to their evolutionary and ecological success.” “

Dinosaurs ruled the land during the Mesozoic Era until their extinction 66 million years ago. These included huge vegetarian groups like the long-necked sauropods and carnivorous species like Tyrannosaurus rex and its relatives. However, their origins were much more humble, dating back to the Triassic when the first definitive dinosaurs appeared around 235 million years ago.