THIS ancient animal hunted and ate the dinosaurs, reveals study

Deinosuchus , one of the biggest crocodilians that ever lived, had a body as long as a school bus and teeth the size of bananas. From 82 to 75 million years ago, this giant predator lived in rivers and estuaries across North America. Though it had a broad snout like an alligator, scientists now say Deinosuchus was something else entirely.

According to a new study published Wednesday in Communications Biology, Deinosuchus was not part of the alligator family after all. The research team used fossil evidence and DNA from living crocodilians to build a new family tree. It shows that Deinosuchus is more closely related to crocodiles than to alligators.

Modern crocodiles have salt glands that help them survive in seawater. Deinosuchus had those glands, too, but alligators do not. That detail is key. Salt tolerance would have allowed Deinosuchus to swim across the Western Interior Seaway—a vast sea that once split North America in two during a time of high global sea levels.


“With salt glands, Deinosuchus could go where alligators couldn’t,” said Dr. Márton Rabi, a senior study author and lecturer at the University of Tübingen in Germany. “We are talking about an absolutely monstrous animal. Definitely around 8 meters (26 feet) or more total body length,” Rabi told CNN.

Toothmarks on dinosaur bones show Deinosuchus hunted or scavenged them. “No one was safe in these wetlands when Deinosuchus was around,” Rabi said.

Fossils of Deinosuchus have been found on both sides of the ancient seaway. The largest species, Deinosuchus riograndensis, lived along the eastern edge of an island called Laramidia, which made up less than a third of the North American landmass. The other large landmass was known as Appalachia.

For a long time, scientists believed Deinosuchus was part of the alligatoroid group. But this didn’t make sense. Alligators only live in freshwater today. How could Deinosuchus cross a sea more than 1,000 kilometers wide? One theory was that early alligators once had salt glands and later lost them. But that idea had little evidence and depended on Deinosuchus being an alligator relative.


The fossil record didn’t support the idea that Deinosuchus spread across North America before the sea formed, either. “The picture wasn’t very coherent,” Rabi said.

To fix that, the researchers added data from extinct crocodilians that hadn’t been used in previous studies. These “missing links” helped clarify the evolution of salt tolerance and other traits.

“Our analysis found that saltwater tolerance is a fairly ancient trait of many crocodilians, and was secondarily lost in the alligatoroids,” Rabi said.


The researchers also found that the first alligators were smaller than other crocodilians of the time. They didn’t grow large until about 34 million years ago—long after Deinosuchus lived.

Rabi said the smaller size of early alligatoroids is another clue that Deinosuchus was not one of them. “Dwarfism in early alligatoroids was another clue that giant Deinosuchus was no ‘greater alligator.’”

The study also found that huge crocodilians like Deinosuchus evolved again and again over the past 120 million years, even during ice ages. According to Rabi, “Giant crocs are more like the norm of any time.”