First Dinosaurs Ate Pretty Much Everything

A team of University of Bristol paleobiologists has found that the earliest dinosaurs included carnivorous, omnivorous, and herbivorous species.
The scientists looked at the tooth shapes of the earliest dinosaurs and compared them to living reptiles and their diets. They found that many groups of plant-eating dinosaurs were ancestrally omnivorous and that the ancestors of long-necked herbivores, such as Diplodocus, ate meat.
This ability to diversify their diets early in their evolution likely explains their evolutionary and ecological success. The earliest dinosaurs are not well understood in terms of their diets and ecology, but scientists know that something must have happened during the Triassic period that allowed dinosaurs to survive the Triassic-Jurassic mass extinction and adapt, becoming the dominant group for the rest of the Mesozoic era.
Lead author Dr. Antonio Ballell from the University of Bristol said “Soon after their origin, dinosaurs start to show an interesting diversity of skull and tooth shapes. For decades, this has made paleontologists suspect that different species were already experimenting with different kinds of diets. They have compared them to modern lizard species and tried to infer what they ate based on the similarities in their teeth.
“We investigated this by applying a set of computational methods to quantify the shape and function of the teeth of early dinosaurs and compare them to living reptiles that have different diets. This included mathematically modeling their tooth shapes and simulating their mechanical responses to biting forces with engineering software.”
The scientists used computational methods to quantify the shape and function of the teeth of early dinosaurs and compare them to living reptiles with different diets. They also used machine learning models to classify the earliest dinosaurs in different diet categories based on their tooth shape and mechanics.
The study found that ornithischians, which include many plant-eating species, started off as omnivores and that the earliest sauropodomorphs, ancestors of long-necked sauropods like Diplodocus, were carnivores. This shows that herbivory was not ancestral for either group or that the diets of early dinosaurs were diverse.