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(CNN) – A massive and extinguished reptile which once nibbled dinosaurs had a large muzzle like an alligator, but it owed its success to a lack that is lacking in modern alligators: tolerance for salt water.
Deinosuchus was one of the greatest crocodilians who ever lived, with a body almost as long as a bus and teeth in the size of bananas. About 82 million years ago, the first predator swam in the rivers and estuaries of North America. The skull was wide and long, tilted with a bulbous bump that did not look like any skull structure observed in other crocodilians. The teeth on the Cretaceous bones suggest that Deinosuchus has driven or recovered dinosaurs.
Despite its scientific name, which translates into “terrorist crocodile”, Deinosuchus has generally been called “biggest alligator”, and previous assessments of its evolutionary relations have gathered it with alligators and their former parents. However, a new analysis of fossils, as well as the DNA of living crocodilians such as alligators and crocodiles, suggests that Deinosuchus belongs to a different part of the Crocodilian family tree.
Unlike alligatoroids, Deinosuchus has retained the salt glands of ancestral crocodilians, allowing it to tolerate salt water, scientists reported on Wednesday in the journal Communications biology. Modern crocodiles have these glands, which collect and release an excess of sodium chloride.
Salt tolerance would have helped deinosuchus to sail in the Western inner maritime route which once divided North America, during a greenhouse phase marked by the world elevation of sea level. Deinosuchus could then have spread through the continent to live in the coastal marshes of the two sides of the ancient inner sea and the Atlantic coast in North America.
The revised genealogical tree of the new study for Crocodilians offers new information on climate resilience in the group and alludes to the way in which certain species have adapted to environmental cooling while others have turned off.
The salt glands allowing Deinosuchus to travel where its alligators cousins could not, the terrorist crocodile settled in habitats teeming with great prey. Deinosuchus has evolved to become a huge and widespread predator that dominated marshy ecosystems, where he fed about everything he wanted.
“No one was safe in these wetlands when Deinosuchus was there,” said Dr. Márton Rabi, author of the study, a speaker from the Institute of Geosciences at the University of Tübingen in Germany. “We are talking about an absolutely monstrous animal,” Rabi told CNN. “Certainly about 8 meters (26 feet) or more the total length of the body.”
Since the middle of the 19th century, deinosuchus fossils have been found on both sides of the old Marine vore and belong to at least two species. The largest of them, deinosuchus riograndensis, lived on the west side, along the east coast of an island called Laramidia. Bordered to the west by the peaceful ocean, Laramidia made up less than a third of the land mass in North America. The other island part of the continent was known as the Appalache.
While Deinosuchus had long been classified as a parent of alligator, his distribution on both sides of this vast seaway was an unresolved puzzle. If it was an alligatoroid – a group that only lives in fresh water – how deinosuchus today could cross a sea covering more than 620 miles (1,000 kilometers)? One hypothesis suggested that the first alligators were tolerant with salt water and then lost the line. But this interpretation did not have much evidence to support it; He only relied on deinosuchus included in the Alligator group, Rabi explained.
Another possible explanation was that Deinosuchus dispersed through North America before the Western inner maritime route formed and divided Western and Eastern populations. However, the fossil file does not support it. The seaway appeared approximately 100 million years ago, which makes it approximately 20 million years more than the first known fossils of deinosuchus.
“The photo was not very consistent,” said Rabi.
For the new analysis, the researchers incorporated data from extinguished crocodilians which were not sampled for the group’s previous family trees. These “missing links” helped the team connect species that were not recognized before to be linked and to reflect the order in which certain traits have emerged in the group.
“Our analysis has revealed that salt water tolerance is a fairly old line of many crocodilians, and has been secondly lost in the alligators,” said Rabi. Even having a moderate tolerance for salt would have greatly benefited the former parents of crocodiles while climate change resumed their habitats, said Dr. Evon Hekkala, professor and president of the Department of Biological Sciences at Fordham University in New York.
“This ecological trait would have enabled crocodile lines in the past to be more opportunistic at times when drastic environmental changes, such as elevation of sea level, caused extinctions in less tolerant species,” said Hekkala, who was not involved in the study.
Researchers have also built a new Crocodilian family tree using modern crocodilian molecular data to clarify the characteristics shared by all alligators. The first alligators were much smaller than the other Crocodilians who lived at the same time, noted the team. The alligators began to develop the largest body sizes seen today about 34 million years ago, after the climate has cooled and their competition died. But when the alligators appeared for the first time, Deinosuchus would have been an aberrant value because of its massive volume, according to the new study.
Nanism in the first alligatoroids was another clue according to which the giant deinosuchus was not a “biggest alligator”, and it probably diverged in a different branch of the family tree before the alligators were evolving, said Rabi.
The study approach – combining a new molecular tree with morphology, or analysis of body forms and skulls in crocodilians – paints a clearer image of the way Deinosuchus has evolved, Hekkala said. The distance of deinosuchus of the alligatoroids “much better corresponds to our current understanding of ecological flexibility among the extinct and alive crocodiles,” she added. “This new document really reaches the evolutionary and ecological role of this amazing animal.”
While Deinosuchus was one of the greatest crocodilians, he was not the only giant. Massive crocodilians have evolved independently in aquatic environments more than a dozen times in the last 120 million years in all types of global climate phases – including ice age, according to the study. Even in living species, relationships of individuals measuring 23 feet (7 meters) or more persisted until the 19th century, suggesting that the huge deinosuchus was the rule rather than the exception.
“Giant fangs are more like the standard – at any time,” said Rabi.
Mindy Weisberger is a scientific writer and media producer whose work has appeared in Live Science, Scientific American and How It Works Magazine.