A comprehensive new study explores the diets of early dinosaurs and, not surprisingly, finds that they included carnivores, herbivores and omnivores. What is surprising, however, is that the ancestors of many of the most famous herbivores, such as Triceratops and Brachiosaurus, originally ate meat.
When we think of dinosaurs, most people think of classic giants: the fearsome Tyrannosaurus Rex, the horned Triceratops, and the long-necked Brachiosaurus. But all of these iconic species emerged fairly late in the game, towards the end of dinosaurs’ reign on Earth. They were generally much smaller when they first evolved about 170 million years ago.
Not much is known about these early dinosaurs, including what many species ate. For the new study, researchers at the University of Bristol investigated the diets of 11 early species from his three major lineages of ornithischians, sauropods and theropods.
Teeth are the biggest clues to the diet of extinct animals. Carnivores have sharp, butcher-like teeth that help them pierce and tear meat, while herbivores usually have broad, flat teeth that help them grind up plants. This is how Bristol scientists conducted their research.
“We explored this by applying a suite of computational methods that quantify the shape and function of early dinosaur teeth and compare them to living reptiles with different diets,” said the study’s lead author. One Dr. Antonio Burrell said: “This involved mathematically modeling the tooth geometry and using engineering software to simulate the mechanical response to bite forces.”
From this, the team found some pretty compelling evidence of a diverse diet for these early dinosaurs, including carnivores, herbivores, and omnivores. For example, early theropods had blade-like teeth similar to modern monitor lizards, which mostly ate meat. Given that later theropods included famous carnivores like T-rex and raptors, this is not at all surprising.
But more unexpected news came from two other groups. Both later evolved into a wide variety of herbivores, but many of their ancestors seem to have started eating meat in some way.
“Our analysis reveals that the Ornithischians — a group that includes many plant-eating species such as horned dinosaurs, crustaceans and platypus dinosaurs — began as omnivores.” One interesting finding is that the earliest sauropods, ancestors of vegetable long-necked sauropods like Diplodocus, were carnivores. It shows that animals are not the ancestors of either of these two lineages, and that the diets of early dinosaurs were very diverse.”
This diversity in diet is likely why dinosaurs were able to thrive for so long, the researchers say. When they first appeared, they were second only to another large group of reptiles.
“One of the things that made the first dinosaurs so special was that they evolved different diets throughout the Triassic, and I suspect that this was the key to their evolutionary and ecological success. “It’s been a long time coming,” said Ballell.
A study was published in a journal scientific progress.
Source: University of Bristol