'Most dinosaurs were vegetarian'

The study, published in the journal Proceedings of the National Academy of Sciences, was carried out on the food diets of 90 species of theropod dinosaurs.

All theropod dinosaurs, a group of bipedal dinosaurs including the iconic hunter Tyrannosaurus Rex, were commonly believed to be flesh-eating beasts.

However, the new study has found out there are many plant-eating dinosaurs among the theropod species known as Coelurosaurs.

Coelurosaurs are also believed to be the closest ancestors of today's birds.

"Most theropods are clearly adapted to a predatory lifestyle, but somewhere on the line to birds, predatory dinosaurs went soft," The Telegraph quoted Dr. Lindsay Zanno of the Chicago Field Museum as saying.

Previously, researchers could only deduce the diets of most Coelurosaurs since only the fossilized bones and teeth of them were left for scientists to work with.

However, recent discoveries of fossilized dinosaur dung, stomach contents, tooth marks, and the presence of stones within the stomach, which serve as a gastric mill for digesting vegetation, helped shed light on the evolution of diets in most Coelurosaurs.

Anatomical features statistically linked to herbivory food habits such as a toothless beak were also found

The evolved vegetarian diet of most Coelurosaurs is believed to have helped the animals survive and exploit new environments and become the most successful group of dinosaurs throughout the Cretaceous Period, 145-65 million years ago.

"The ability to eat plant materials may have played a pivotal role in allowing Coelurosaurian dinosaurs to achieve such remarkable species diversity,” Zanno said.

Since such giant hunters as T Rex and Velociraptor also belong to the Coelurosaurian species, their carnivorous food eating habits is now considered as “exceptions.”