The exotic pet trade brings millions of animals into the U.S. every year. One of these animals, the tegu, is a popular reptile import thanks to its flashy looks and docile personality. Once it grows to its full 5-foot, 10-pound size, however, it often ends up escaping or being set free into the wild. In Florida, it is considered an invasive species and is of special interest to wildlife biologists and conservationists since it’s a menace to local ecosystems. 

Recently, the tegu has become of special interest to another group in Florida – paleontologists from the Florida Museum of Natural History. 

“We have all of these fossil bones, so I was digging through, and I kept coming across this one vertebra. I could not figure out what it was,” said Jason Bourque, a fossil preparator in the museum’s vertebrate paleontology division, in a press release. “I put it away for a while. Then I’d come back and say: Is it a lizard? Is it a snake? In the back of my mind for years and years. It just sat there.” 

The fossil in question turned out to be from a prehistoric tegu. This find confirms that tegus aren’t so invasive after all and were roaming the Florida shores millions of years before their modern counterparts got shipped over in the 1990s.

Read More: Giant Tegu Lizards Are Moving Into Georgia — and They’re Not Welcome

Solving a Tegu Fossil Mystery

This new breakthrough in the tegu’s story, published in the Journal of Paleontology, came from a single, half-wide vertebra fossil. The fossil was found in a clay mine just north of the Florida border that was scheduled to be closed and filled in. Scientists were alerted to the fossil and had to excavate as many fossils as possible before the mine’s quickly approaching closing date. The tegu fossil was one of the collected specimens and was transported back to the museum in a box that sat in storage, unidentified for twenty years. 

While doing some unrelated research years after finding the fossil in storage, Bourque came across an image of a tegu vertebra. He recognized the image right away. But since there was no fossil record of tegus existing in North America, he needed more evidence to support his find.

Bourque and colleagues used machine learning to help solve the puzzle of the tegu vertebrae. Using CT scans of the fossil, they carefully mapped the vertebrae and then compared their results to over 100 modern tegu vertebrae images in the museum’s database.

The fossil was enough of a match to confirm it belonged to a tegu. However, it wasn’t an exact match, which led the team to an exciting conclusion: they had discovered a new species.

A New Species of Tegu

This new species of tegu would’ve been around during the Middle Miocene Climatic Optimum. During this period, Earth’s temperatures were exceptionally warm, and sea levels were high. At the time, Florida would’ve been mostly underwater, with the historic coastline being near where the fossil was found.

Tegus are land-dwellers, but they are also very strong swimmers, so it isn’t too hard to believe that they swam across from South America to enjoy the high temperatures. Their time in North America didn’t last long, however, as the temperatures dropped and the tegus would’ve struggled to produce or hatch eggs.

“We don’t have any record of these lizards before that event, and we don’t have any records of them after that event. It seems they were just here for a blip, during that really warm period,” said Bourque in the press release.

Finding More Prehistoric Lizard Fossils

The team hopes to find more tegu fossils from this period to help fill in the missing pieces about the prehistoric lizard’s short visit to North America. There is worry that more tegu fossils are withering away in storage boxes, waiting to be found. 

The growing use of 3D modeling and artificial intelligence to identify fossils may help excavate these fossils from their stashed-away boxes. Advances in machine learning could even one day provide the technology to create a global fossil identification database, which would significantly speed up and simplify the process.

“There are boxes full, shelves full, of fossils that are unsorted because it requires a huge amount of expertise to identify these things, and nobody has time to look through them comprehensively,” said Edward Stanley, director of the museum’s digital imaging laboratory, in the press release. “[This discovery] is the first step towards some of that automation, and it’s very exciting to see where it goes from here.”

Read More: Iguanas Floated 5,000 Miles to Colonize Fiji Millions of Years Ago

Article Sources

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As the marketing coordinator at Discover Magazine, Stephanie Edwards interacts with readers across Discover’s social media channels and writes digital content. Offline, she is a contract lecturer in English & Cultural Studies at Lakehead University, teaching courses on everything from professional communication to Taylor Swift, and received her graduate degrees in the same department from McMaster University. You can find more of her science writing in Lab Manager and her short fiction in anthologies and literary magazine across the horror genre.