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發表於 2025-5-14 06:35:46
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An ancient ‘terror crocodile’ became a dinosaur-eating giant. Scientists say they now know why
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A massive, extinct reptile that once snacked on dinosaurs had a broad snout like an alligator’s, but it owed its success to a trait that modern alligators lack: tolerance for salt water.
Deinosuchus was one of the largest crocodilians that ever lived, with a body nearly as long as a bus and teeth the size of bananas. From about 82 million to 75 million years ago, the top predator swam in rivers and estuaries of North America. The skull was wide and long, tipped with a bulbous lump that was unlike any skull structure seen in other crocodilians. Toothmarks on Cretaceous bones hint that Deinosuchus hunted or scavenged dinosaurs.
Despite its scientific name, which translates as “terror crocodile,” Deinosuchus has commonly been called a “greater alligator,” and prior assessments of its evolutionary relationships grouped it with alligators and their ancient relatives. However, a new analysis of fossils, along with DNA from living crocodilians such as alligators and crocodiles, suggests Deinosuchus belongs on a different part of the crocodilian family tree.
Unlike alligatoroids, Deinosuchus retained the salt glands of ancestral crocodilians, enabling it to tolerate salt water, scientists reported Wednesday in the journal Communications Biology. Modern crocodiles have these glands, which collect and release excess sodium chloride.
Salt tolerance would have helped Deinosuchus navigate the Western Interior Seaway that once divided North America, during a greenhouse phase marked by global sea level rise. Deinosuchus could then have spread across the continent to inhabit coastal marshes on both sides of the ancient inland sea, and along North America’s Atlantic coast.
The new study’s revised family tree for crocodilians offers fresh insights into climate resilience in the group, and hints at how some species adapted to environmental cooling while others went extinct.
With salt glands allowing Deinosuchus to travel where its alligatoroid cousins couldn’t, the terror crocodile settled in habitats teeming with large prey. Deinosuchus evolved to become an enormous and widespread predator that dominated marshy ecosystems, where it fed on pretty much whatever it wanted.
“No one was safe in these wetlands when Deinosuchus was around,” said senior study author Dr. Marton Rabi, a lecturer in the Institute of Geosciences at the University of Tubingen in Germany. “We are talking about an absolutely monstrous animal,” Rabi told CNN. “Definitely around 8 meters (26 feet) or more total body length.” |
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