We tend to think of crocodilians as relics of a bygone era – lesser reptiles that somehow managed to survive among the dinosaurs who found their stride in the age of mammals. Not so, says an international study: Scientists have found that 13 million years ago, as many as seven species of crocodilians were widespread across the Amazon region.
The findings are based on a treasure trove of fossils found in the western Amazon that indicate that seven species of crocodilians – including the well-known American Aligator – were once found coexisting in the same territories.
“It was a real crocodilian community,” study co-author Rodolfo Salas-Gismondi of the Museum of Natural History in Lima, Peru told USA Today. “To find seven species … is just amazing.”
The cavalcade of crocs also included species no longer on Earth today. Purussaurus neivensis was an apex predator that chowed on turtles and mammals, while Mourasuchus atopus was a giant thought to feed by filtering fish out of water through its teeth.
The biggest findings were three species previously unknown to scientists. All three are so-called “crushing crocs,” believed to feed by crushing the shells of buried molluscs with powerful jaws. Gnatusuchus, or “short-nosed crocodile” had a stubby, rounded snout and chunky back teeth particularly well-suited to the job. The two others, though different, appear to show a link between modern caimans and earlier ancestors.
“I didn’t really think of crocs as being clam-eaters before,” vertebrate paleontologist David Schwimmer of Georgia’s Columbus State University, who was not involved with the research, told USA Today. “It’s not exactly ferocious, hunting down the giant killer clam. Just think of the image.”
The immense crocodilian diversity is thought to be a product of the environment at the time: The area outside the Peruvian city of Iquitos would have been a warm, lush bountiful wetland at the time. There would have been plenty of prey to support multiple species of crocs, especially if some of them were resigned to digging clams out of the mud.
Today, the same area is home to just three species of crocodilians. Despite that, there are parts of the Amazon basin that, in the dry season, host the densest concentration of crocodilians found anywhere in the world. You may not have seven species to fear, but the region still very much belongs to the crocs.