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The species of alligator roaming Florida's swamps and golf courses may be millions of years older than previously thought, scientists from the University of Florida said.

What's more, the sharp-toothed reptiles we see today may be almost biologically identical to their millennia-old ancestors -- an incredibly rare trait for most living species, according to a pair of studies shared with Mashablethis week.

"What we saw 8 million years ago in Florida is virtually the same thing as what we have there today," Evan Whiting, the studies' lead author and a vertebrate paleontologist, said by phone from Gainesville.

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Whiting and his research team compared the fossils of the American alligator (Alligator mississippiensis) with those of extinct alligator species. They found that the minute differences in each species' forms were instead just variations of the same singular species.

Greetings from your nightmares.Credit: RHONA WISE/AFP/Getty Images

Their findings extend the American alligator's lineage by about 6 million years, according to the study published in the Journal of Herpetology. Scientists had previously believed the species emerged about 2 million years ago, when the most recent Ice Age began.

"To hit this exact set of features in the American alligator, and for them to keep such a huge presence in the area that's now the Southeast U.S. for 7 to 8 million years, is nothing short of spectacular," Alex Hastings, the assistant curator of paleontology at the Virginia Museum of Natural History, told Mashable.

"The fact that their populations are doing pretty well today is a testament to their evolutionary success," said Hastings, who was not involved in the University of Florida studies.

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The Florida researchers also found that, millions of years ago, American alligators shared the Florida peninsula with a species of 20-foot-long crocodiles, according to a separate study in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

While the crocs fed mostly on marine-based prey, the alligators stuck to freshwater or terrestrial sources -- a trait that still persists in American alligators, which lack the salt-secreting glands needed to thrive in saltwater.

The Alligator mississippiensis has proved resilient to naturally occurring changes in the climate and environment over millions of years. But in the modern era, the species' survival is increasingly at risk.

Map of the modern continental U.S. showing the rough geographic range of the American alligator.. Nebraska inset (top right) shows approximate localities for Alligator thomsoni (1) and Alligator mefferdi (2) fossils. Florida inset (bottom right) shows approximate localities for the Alligator olseni (3) fossils and the location of the Moss Acres Racetrack Alligator (4).Credit: journal of herpetology/"Cranial Polymorphism and Systematics of Miocene and Living Alligator in North America"

Florida's booming population and sprawling real estate have steadily destroyed the alligators' habitat in recent decades. The reptiles landed on the U.S. endangered species list in the late 1960s, although the species was removed in the 1980s after the population recovered thanks to habitat protection efforts.

Encroaching on alligators' habitat has dangerous consequences for humans, as well. In June, an alligator killed a toddler visiting Walt Disney World in Orlando, marking the fourteenth deadly alligator attack in Florida since 2000.

Human-caused climate change poses another serious threat to the American alligator. Florida's low-lying landscape and porous bedrock make it particularly vulnerable to rising sea levels and saltwater intrusion, which could destroy the gators' freshwater dwellings along with homes and communities across the peninsula.

An American Alligator swims in Everglades National Park, Florida, on June 23, 2016.Credit: RHONA WISE/AFP/Getty Images

"With increasing sea levels, we may see the available habitat for American alligators disappear," Whiting said.

As Florida sinks underwater and global temperatures warm, the alligator may move north over centuries to perhaps as far north as modern-day South Dakota and Nebraska, where Alligator mississippiensis likely originated.

"These things could be recolonizing parts of the United States that they haven't occupied in millions of years," Hastings said.

(责任编辑：娛樂)