Just when you think you know someone, they surprise you. Alligators and crocodiles are dreaded carnivores that kill at least 1,000 people every year, according to the Gates Foundation. However, new research suggests that the ancestors of these tooth-like reptiles favor plants in some places in their 200-million-year evolutionary history. In fact, during the Mesozoic era, when some crocodile-related predators raided from the half-water, others lived on land and more omnivorous on the palate, modern reptiles known as crocodile-shaped have both all-consuming and herbivorous eating habits. The authors of the paper, Keegan Melstrom, a student at the University of Utah, and Randall Irmis, chief curator of the Natural History Museum of Utah, came to this conclusion after conducting a thorough analysis of fossilized crocodile-shaped teeth. In total, their research teams studied 1
"We see all of these tooth forms in the history of reptile development and some of them are quite simple, but others simply have no comparison," said Irmis in a press release from the Natural History Museum of Utah.
The researchers then did highly detailed digital scans of the different teeth and analyzed them using a method called Orientation Patch Count Rotated (OPCR) that "quantifies the complexity of the occlusal tooth surface in distantly related animals," as explained in the paper. Essentially, OPCR treats teeth as miniature mountains and measures the topographic complexity of each tooth. Previous studies have shown that the more complex a tooth is, the more animal it consumes.
"Some of the crocodiles that were considered herbivores are more insectivores and omnivores," said Irmis.
There were a few surprises. A crocodile named Notosuchus from Argentina was considered an herbivore. "My work, however, strongly suggests that it is a carnivore."
The results provide more insight into how an environment affects evolution, but not what you think. For example, herbivorous reptiles do not always develop in environments where no herbivorous mammals are present to fill a niche.
"This tells me you do not need a single special environment for it … It's something that's a nutritional strategy that's really successful," Melstrom noted.