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'Polar bear lizard' was the tiny T. rex of the Arctic

'Polar bear lizard' was the tiny T. rex of the Arctic

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Fiorillo, Tykoski (PLOS ONE)

When the fossils of Nanuqsaurus hoglundi were discovered in the Arctic three decades ago, scientists thought they belonged to a whale, reports the AFP. But a second, more recent look from researchers in Texas revealed that the fossils actually belonged to a diminutive Tyrannosaurus rex relative that roamed Alaska's north over 66 million years ago.

23 feet from tooth to tail

Found 400 miles northwest of Fairbanks, Alaska, this miniature tyrannosaurine measured 6.5 feet at the hip and almost 23 feet from tooth to tail. This may seem rather tall, but if you compare its size with a T. rex, an animal whose hips were 13 feet above the ground, N. hoglundi — nicknamed the "polar bear lizard" — does seem just a tad tiny.

Scientists think that its small size may have been advantageous in the harsh Arctic conditions because the scarce resources in the area would not have been enough to satisfy a larger animal. But the researchers didn't figure that out until later: Ronald Tykoski, fossil preparator at the Perot Museum of Nature and Science in Dallas and co-author of the study published in PLOS ONE yesterday, admitted to the Guardian that it took him a while to realize that he was looking at "a mature individual of something new," and not the remains of a youngster. "It is absolutely a pygmy tyrannosaur," he said.

"But there's still a possibility that it's a young one."

Other scientists, however, question whether the polar bear lizard was fully-grown. "It's certainly a small individual," Roger Benson, a vertebrate paleontologist at Oxford University who did not participate in the study, told the Guardian. "But there's still a possibility that it's a young one." Benson said that despite the adult features highlighted in the study, the researchers still need to look at cross sections of the bone, which "would give them growth lines" that would tell them "fairly reliably if something is mature or not."

The researchers hope that further trips to Alaska will yield more fossils. Along with other recent discoveries in the area, including a horned herbivorous dinosaur named P. perotorum, the scientists believe that this discovery will help them gain a better understanding of prehistoric life in the Arctic.