Fossil reveals “crocodile of terror” that hunted dinosaurs

An extinct gigantic reptile that used to feed on dinosaurs had a wide muzzle like a alligator, but was due to a characteristic that modern alligators do not have: saltwater tolerance. The discovery was reported in a study published on Wednesday (23) on Wednesday in Communications Biology magazine.

THE Deinosuchus It was one of the largest crocodilians ever, with a body almost as long as a bananas -size bus and teeth. Approximately 82 to 75 million years ago, this dominant predator swam in North America rivers and estuaries.

The skull was wide and long, with a bulbous protuberance at the tip, unlike any cranial structure seen in other crocodilians. Tooth marks on bones of the Cretaceous suggest that the Deinosuchus He hunted or fed on dinosaurs.

Despite its scientific name, which means “crocodile terror”, the Deinosuchus It is commonly called “greater alligator”, and previous evaluations of its evolutionary relationships grouped it with alligators and their old relatives. However, a new analysis of fossils, along with living DNA of living crocodilians such as alligators and crocodiles, suggests that the Deinosuchus It belongs to a different part of the Crocodilian genealogical tree.

Unlike the aligatororoids, the Deinosuchus kept the salt glands of the ancestral crocodilians, allowing to tolerate salt water, scientists reported in the study. Modern crocodiles have these glands, which collect and release excess sodium chloride.

Tolerance to salt would have helped the Deinosuchus Navigating Western Setern Seaway, which once divided North America during a greenhouse phase marked by the overall rising sea level. THE Deinosuchus He could then have spread across the continent to inhabit coastal swamps on both sides of the old inner sea and along the Atlantic coast of North America.

The revised genealogical tree of the new crocodilian study offers new insights on the group’s climate resilience and suggests how some species adapted to environmental cooling while others were extinguished.

With salt glands that allowed the Deinosuchus Traveling where their aligatoroid cousins ​​could not, the terror crocodile established itself in habitats full of large prey. THE Deinosuchus He evolved to become a huge and disseminated predator who dominated swamp ecosystems, where he fed on practically everything he wanted.

“No one was safe in these swamps when the Deinosuchus It was around, ”says senior study author Dr. Marton Rabi, professor at the Institute of Geosciences at the University of Tübingen, Germany.“ We are talking about an absolutely monstrous animal, ”Rabi tells Rabi to CNN . “Definitely about 8 meters or more in full length.”

An atypical case among alligators

Since the mid -nineteenth century, fossils of Deinosuchus They were found on both sides of the old sea and belong to at least two species. The largest of them, Deinosuchus riograndensislived on the west side, along the east coast of an island called Laramidia. Limited to the west by the Pacific Ocean, Laramidia made up less than a third of North America. The other island portion of the continent was known as apalaches.

Although the Deinosuchus It has long been classified as a relative of alligator, its distribution on both sides of this vast sea channel was an unresolved riddle. If it were an aligatoroid – a group that today lives only in freshwater – like the Deinosuchus Could you cross a sea over 1,000 kilometers long? One hypothesis suggested that the first alligators were tolerant to saltwater and later lost this feature. But this interpretation did not have much evidence to support it; depended only on the inclusion of Deinosuchus In the group of aligatoroid, Rabi explained.

Another possible explanation would be that the Deinosuchus He dispersed in North America before the formation of the Western inner sea, dividing Western and Eastern populations. However, the fossil registration does not prove it. The sea viae came about 100 million years ago, which makes it approximately 20 million years older than the first known fossils of Deinosuchus.

“The image was not very coherent,” says Rabi.

For the new analysis, the researchers incorporated data from extinct crocodilians who were not sampled into the group’s previous genealogical trees. These “lost links” helped the team connect species that were previously not recognized as related and to reassemble the order in which certain traits arose in the group.

“Our analysis found that saltwater tolerance is a very old feature of many crocodilians, and has been secondarily lost in aligatoroids,” says Rabi.

Having a moderate tolerance to salt would have greatly benefited the former relatives of crocodiles as climate change reshaped their habitats, according to Evon Hekkala, professor and head of the Fordham University Department of Biological Sciences in New York.

“This ecological feature would have allowed crocodile strains in the past to be more opportunistic at times when drastic environmental changes, such as rising sea level, were causing extinctions in less tolerant species,” says Hekkala, who did not participate in the study.

It is not a “bigger alligator”

The researchers also built a new crocodilian genealogical tree using molecular data from modern crocodilians to clarify characteristics shared by all aligatororoids. The first alligators were much smaller than other crocodilians who lived at the same time, the team discovered.

Alligators began to evolve into the larger body sizes seen today about 34 million years ago, after the weather cooled and its competition was extinguished. But when the aligatororoids first appeared, the Deinosuchus It would have been a case apart due to its huge mass, according to the new study.

Dwarfism in the first aligatororoids was another clue that the giant Deinosuchus It was not a “big alligator”, and probably diverged to a different branch of the family tree before the aligatororoids evolved, according to Rabi.

The study approach – combining a new molecular tree with morphology, or analysis of body and cranial forms in crocodilians – paints a clearer picture of how Deinosuchus Evolved, says Hekkala. Ward off Deinosuchus Of the aligatororoids “it fits much better with our current understanding of ecological flexibility among extinct and living crocodiles,” he adds. “This new article really reaches both the evolutionary and ecological role of this amazing animal.”

Although the Deinosuchus It was one of the greatest crocodilians, was not the only giant. Massive crocodilians have evolved independently in aquatic environments over a dozen times in the last 120 million years during all types of global climate phase – including glacial ages, according to the study. Even in living species, reports of individuals measuring 7 meters or more persisted until the nineteenth century, suggesting that the huge Deinosuchus It was the rule and not the exception.

Fossils reveal as reptiles of the time of dinosaurs flew

This content was originally published in fossil reveals “crocodile of terror” that hunted dinosaurs on the CNN Brazil website.

Source: CNN Brasil

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