It was another time. By the end of the Cretaceous, North America was beaten in two by a giant inland sea. Dinosaurs, near the end of their reign, still abound in this hot, wet place. But they had to watch their step, especially through the edge of the water.
In the shallow lake Deinosuchus: the ‘terror crocodile’. This giant extinct crocodile was the largest carnivore in its semi-aquatic environment – a powerful apex predator that would feed on dinosaurs even if they poached too close.
Deinosuchus fossils were first discovered in the US in the 1850s and have been studied for more than a century, but species classifications within the genus have long been debated.
In a new study, researchers from the University of Iowa looked at existing fossil evidence, and also looked at newly collected fossil specimens.
Deinosuchus swimmeri skull. (Cossette & Brochu, Journal of Vertebrate Paleontology, 2020)
The results of their phylogenetic re-evaluation suggest three distinct types of Deinosuchus can be distinguished in the fossil record: the kind that has the suggestion D. riograndensis, D. hatchery, and a newly identified species, D. schwimmeri.
“Deinosuchus was a giant who had to terrorize dinosaurs who came to the edge of the water to drink, “says lead researcher and paleontologist Adam Cossette, now with the New York Institute of Technology.
“Until now, the entire animal was unknown. These new specimens we examined revealed a bizarre, monstrous predator with teeth the size of bananas.”
While the oldest known Deinosuchus the specimen to date is about 82 million years old, the researchers say a common ancestral population for all different species is likely, and would have existed in North America before rising seas allowed the Western Interior Seaway to cut the continent in half cut.
When this happened, the researchers speculated that different environments on the east and west coasts led to evolutionary adjustments that resulted in the slightly different morphologies and body size of D. riograndensis, D. hatchery, en D. schwimmeri.
Artist’s impression of Deinosuchus. (Tyler Stone)
“It was a strange animal,” says paleontologist Christopher Brochu. “It shows that crocodiles are not ‘living fossils’ that have not changed since the age of dinosaurs. They have evolved just as dynamically as any other group.”
Based on the fossil evidence, D. riograndensis en D. hatchery spent their dinosaur hunting days in western North America, from Montana to northern Mexico. D. schwimmerimeanwhile lived along the Atlantic coast, between New Jersey and Mississippi.
Regardless of their coastal associations, however, these giant creatures – which ran up to 10 meters (33 ft) in length – were some of the largest and most terrifying crocodilians ever, and were closer in appearance to modern alligators than crocodiles.
“At the time it lived here in the eastern U.S., there was nothing bigger,” Columbus State University geologist and paleontologist David Schwimmer told the Ledger-Enquirer.
Schwimmer was not involved in the new study, but was the inspiration for the naming of D. schwimmeri, given his contributions to the field.
“We actually have bites of these guys on dinosaur tapes. Now, the only question you can ask is: Are they rattlesnakes or predators?” Be a swimmer.
“My judgment is predatory … This creature was large enough to take down most dinosaurs. Also interestingly, most of the bites we see are in paw bones and tailbones. If you are going to grab a dinosaur, then that’s the place you’ll pick them up. “
The findings are reported in Journal of Vertebrate Paleontology.
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