The menu for the first dinosaurs – New Scientist

The first dinosaurs had a surprisingly varied diet. This is shown by extensive research into the shape of their teeth.

The first dinosaurs lived about 230 million years ago, during the Triassic period. These predecessors to more famous dinosaurs such as Tyrannosaurus rex were small, slender bipeds, less than two meters tall. They had a long tail. Little was known about their diet until now.

Steak knife

Most early dinosaurs had sharp, backward-curved teeth with sharp edges that were often serrated. “They had little zigzags, like a steak knife,” says paleontologist Mike Benton of the University of Bristol. ‘Therefore a diet of meat and insects is assumed for the smallest dinosaurs. The problem with these assumptions is that they are guesswork. Reasonable guesses, but not supported by strong evidence.’

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Benton and his colleagues believe they have now found evidence. In the journal Science, they describe how they examined the teeth of the first dinosaurs more extensively, and how, to their surprise, the diet was more varied than expected. Benton: ‘We expected almost all of them to be primarily carnivores. But there is evidence for a mixed, omnivorous diet in many species.’ The early dinosaurs were probably able to eat meat, insects and even plants.

3D scans and crocodile teeth

To understand the diet of sixteen different early dinosaurs, the researchers used two techniques. They tested the mechanical properties of the teeth and compared them to the teeth of modern reptiles such as lizards and crocodiles. It is well known what they eat.

Early dinosaurs and their diet. Lesothosaurus is an omnivore, Buriolestes is a carnivore, and Thecodontosaurus is a herbivore. Photo: Gabriel Ugueto

They determined the mechanical properties of dinosaur and reptile teeth by measuring the shape and other properties of the teeth. To do this, they used accurate 3D scans of the teeth, which they could subject to simulated stress tests in a computer program. This made it possible to determine how the teeth exerted forces on the food and how large those forces were. The researchers combined this information with data on the diet and teeth of today’s reptiles to find out which type of food, which teeth are best suited for. For this analysis they also used machine learninga form of artificial intelligence (AI).

‘It showed that all carnivores had teeth with maximum stress at the tip. The herbivores showed much lower stress values ​​across the tooth,’ says Benton. This means that carnivores can exert more force on a smaller surface area with their teeth. This is useful when they bite hard into their prey to kill the animal or tear the flesh from the dead carcass.

Balanced diet

The research found that the pointed, curved teeth with small serrations of the group of dinosaurs Theropods similar to modern wasps. So, like lizards, they probably ate mainly meat, in the form of small animals and insects. The long-necked teeth Sauropodomorpha more similar to those of modern omnivores and herbivores, such as iguanas.

The results show that later herbivorous species of the group ornithischian, like Edmontosaurus, descended from omnivores. The ancestors of the long-necked sauropod dinosaurs, such as Diplodocus, were primarily carnivores.

This rather varied diet of the early dinosaurs may have been the key to their success. Dinosaurs grew in the later Jurassic and subsequent Cretaceous into the large imposing animals seen in movies and books (not always depicted correctly).

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