Ever wondered what the ancient relatives of modern day crocodiles were like? By looking at ancient crocodile teeth, researchers of a new study found that some of them were actually herbivores or omnivores.

Crocodile Teeth

Typically, carnivores have simple, conical teeth, while herbivores have more complex ones. The teeth of omnivores, or the creatures that eat both meat and plants, fall somewhere in between. When it comes to crocodiles, people often think of the apex carnivorous predators that they are today, with their sharp teeth that can easily cut through flesh. However, a new study found that some of crocodiles’ relatives were actually plant eaters, and that the herbivorous diet actually arose at least three times in their evolution.

In the study, researchers looked at 146 teeth from 16 extinct crocodyliforms. From the beginning, researchers already noticed the differences in the pattern of the teeth of the extinct species, and they were able to determine the diets of the creatures based on quantitative dental measurement as well as other morphological features.

Herbivorous Crocodyliforms

Interestingly, the researchers found that while some of the species were carnivorous just like modern day crocodiles, some had varied omnivorous diets, while others even had herbivorous diets. Those with the carnivorous diets had pointed teeth for killing and eating their prey, but those with herbivorous diets had broader and bumpier teeth that were perfect for grinding leaves and plants. Based on their analysis, herbivorous diets actually arose in some of the extinct species at least three times and up to six times in the Mesozoic crocodyliforms.

“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!” said lead researcher Keegan Melstrom.

What’s more, they also found that the plant-eating crocodyliforms appeared early in the group’s evolutionary history, just after the Triassic mass extinction, and until the end-Cretaceous mass extinction that killed off all dinosaurs.

Now, researchers are continuous in their reconstruction of the extinct creatures’ diets, also in hopes of understanding why the creatures greatly diversified after one mass extinction but not another.

The study is published in Current Biology.