Just when you think you know someone, they turn out to surprise you. Alligators and crocodiles are much-feared carnivores who kill at least 1,000 people a year, according to the Gates Foundation. Yet new research suggests that these toothy reptiles' ancestors may have preferred to eat plants at some points in their 200-million-year evolutionary history. Indeed, it turns out that during the Mesozoic Era, when some crocodile relatives were semi-aquatic ambush predators, others lived on land and had more omnivorous palates.
New research published in Current Biology provides more evidence that the ancient group in which modern reptiles descended from, known as crocodyliforms, adapted both to all-female and herbivorous diets. The authors of the paper, University of Utah degree student Keegan Melstrom and Natural History Museum of Utah Chief Curator Randall Irmis, reached this conclusion after conducting a thorough analysis of the fossilized crocodyliform teeth. In total, their team of researchers studied 1
"We see all these tooth shapes in the history of reptile evolution, and some of they are fairly straightforward, but others just have no comparison, "said Irmis in a Natural History Museum in Utah.
Researchers then took highly-detailed digital scans of the various teeth and analyzed them through a method called Orientation Patch Count Rotated (OPCR), which "quantifies the complexity of the occlusal dental surface in distantly related animals", as the paper explains. In essence, OPCR treats the teeth as miniature mountains and measures how topographically intricate each tooth is. Previous studies have shown that the more complex and tooth is, the more plant material the animal eats.
"Some of the crocs that people thought were strict herbivores are more likely to be insectivores and omnivores," Irmis noted. There were some surprises. A crocodile called Notosuchus from Argentina was thought to be a herbivore, "but my work strongly suggests it's a carnivore," Melstrom said.
The results provide more insight into how an environment affects evolution, but not in the way one would think . For example, it is not always the case that herbivorous reptiles evolve in environments where herbivorous mammals are absent, to fill a niche
"What this says to me is that you do not need a single special environment for this to happen … It's something that's a really successful diet, "Melstrom remarked.