Surprising study finds ancestors of most herbivorous dinosaurs ate meat

A comprehensive new study has examined the diets of the earliest dinosaurs and found that, unsurprisingly, they included carnivores, herbivores and omnivores. But what is surprising is that the ancestors of many of the most famous herbivores – like Triceratops and Brachiosaurus – originally ate meat.

When you picture dinosaurs, most people think of the classic giants – the fearsome Tyrannosaurus rex, the horned Triceratops, or the long-necked Brachiosaurus. But these iconic species all arose fairly late in the game, towards the end of the dinosaurs’ reign on Earth – when they first evolved about 170 million years earlier, they were generally much smaller.

Not as much is known about these early dinosaurs, including what many species ate. So for the new study, researchers at the University of Bristol investigated the eating habits of 11 early species from the three main lineages – ornithischians, sauropodomorphs and theropods.

The biggest clue to an extinct animal’s diet is its teeth. Carnivores have pointed teeth like butcher’s knives, to help them pierce and tear through flesh, while herbivores usually have broad, flat teeth that help them grind up plant matter. And this is how the Bristol scientists conducted their study.