200 million years ago, crocodiles had a different diet to what we know today - instead of eating meat, they were vegetarians.
How did the researchers discover the ancient crocodiles' dietary preferences? By donning their dentists' robes and analyzing their teeth.
Tooth fossils gave the clue to their penchant towards vegetarianism.
Tooth fossils and vegetarianism
It turns out that three to six branches of the crocodile and the alligator family had teeth specialized for plant chewing.
Incredibly, the researchers were able to reconstruct the diet of these plant eaters merely by analyzing these fossilized teeth. The team looked at 146 teeth from 16 different crocodile types.
Keegan Melstrom, the author of the study, said: "Carnivores possess simple teeth whereas herbivores have much more complex teeth."
He continued: "Our study indicates that complexly-shaped teeth, which we infer to indicate herbivory, appear in the extinct relatives of crocodiles at least three times and maybe as many as six. "
The fossils of the teeth used in the study clearly demonstrated that these were non-meat eating reptilians.
Melstrom and Dr. Randall Irmis, chief curator of paleontology at the Natural History Museum in Utah, were able to discover what these animals ate by comparing the tooth complexity of the now-extinct crocodiles with present-day ones.
200 million-year-old teeth
By analyzing the fossilized teeth, the team was able to deduce that at least three to six of the crocodyliforms roamed the Earth during the Mesozoic Era, around 200 million years ago.
The researchers' study enabled them to find out more information about crocodiles in general.
Melstrom said, "Some crocodyliforms were similar to living crocodylians and were primarily carnivorous, others were omnivores (eating both meat and plants), and still others specialized in plants."
He pointed out that "The herbivores lived on different continents at different times, some alongside mammals and mammal relatives, and others did not."
"This suggests that an herbivorous crocodyliform was successful in a variety of environments," he finished.
Quite the change from the crocodylians we know today.