It is widely understood that crocodiles are not to be messed with! One glance at their sharp teeth is enough to send their prey running. However, they weren’t always so vicious. In fact, scientists recently discovered that some ancient crocodiles were herbivores! This means that they mainly ate plants. While these ancient crocs were still robust creatures, they did not possess the same predatory nature as today’s carnivorous crocodiles.

photo of a modern day crocodile

the study

Two paleontologists, Keegan Melstrom and Randall Irmis, recently shared their findings on these ancient crocodiles. They scanned 146 teeth from 16 extinct crocodiles. Melstrom and Irmis studied the scans and gave the teeth a score based on their complexity. Carnivores, or meat-eaters, have sharp, pointy teeth. These teeth scored lower on the paleontologist’s scale. Herbivores have flatter teeth with larger surface areas and more nooks and crannies. These teeth scored higher. The study showed that the teeth of the ancient crocodiles were flat and not very sharp or pointy, meaning they most likely belonged to herbivores.


Melstrom and Irmis’ study concluded that three independent groups of ancient crocodiles in the Mesozoic Era did, in fact, evolve to be herbivores! Scientific evidence shows these ancient crocodiles lived in a variety of environments: saltwater, freshwater, and even on land! Evolving to eat plants was probably a way to survive in these very different environments.


Herbivore: an herbivore is an animal who mainly eats plants.

Carnivore: a carnivore is an animal who mainly eats meat.

Paleontologist: a paleontologist is a scientist who studies the fossils of ancient animals to understand how they have evolved over time.

Mesozoic Era: the Mesozoic Era lasted from 252 million to 66 years ago. This is the same era that dinosaurs lived in.


K.M. Melstrom and R.B. Irmis. Repeated evolution of herbivorous crocodyliforms during the age of dinosaursCurrent Biology. Published online June 27, 2019.

Vernimmen, Tim. “Plant-Eating Crocodiles Thrived in Dinosaur Times.” National Geographic, 27 June 2019,

Wilke, Carolyn. “Ancient Crocodiles May Have Preferred Chomping Plants, Not Meat.” Science News for Students, 29 July 2019,