Meet T. Rex’s New Pygmy Cousin: 'Nanuqsaurus Hoglundi,' Who Roamed The Arctic

By Gabrielle Jonas on March 12, 2014 4:59 PM EDT

It's A, in blue, and he or she is about half the size of its heftier cousin.
The Nanuqsaurus Hoglundi in dark blue, is about half the size of its heftier cousin.
Paleontologists have discovered a new genus and species of a pygmy tyrannosaur that once roamed the ancient Arctic lands of Northern Alaska. The dinosaur is called the Nanuqsaurus hoglundi.  Credit: Illustration by Karen Carr
Paleontologists have discovered a new genus and species of a pygmy tyrannosaur that once roamed the ancient Arctic lands of Northern Alaska. The dinosaur is called the Nanuqsaurus hoglundi. Credit: Illustration by Karen Carr

When paleontologists were excavating a site in northern Alaska eight years ago, they found the fossils of a horned dinosaur they later named after the family of 1992 independent presidential candidate, Ross Perot, who had given $50 million to their Perot Museum of Nature and Science in Dallas. Near Pachyrhinosaurus perotorum (Fiorillo and Tykoski, 2012), they found the  teeth of a  meat-eating dinosaur, as well as an occasional bone riddled with teeth marks.  "That led me to wonder who was eating the horned dinosaur," paleontologist Anthony Fiorillo told the International Science Times in an email interview. "Now we know. That dinosaur was the Nanuqsaurus that ate the Perot dinosaur."

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A few years later, Fiorillo found a piece of skull and some teeth. But that was enough to persuade paleontologist Tykoski, who specialized in dinosaur predators, to spend years extracting and analyzing the bones in Dallas before confirming that this was indeed, a relative of the Tyrannosaurus Rex. Though the bones look like nothing much to a novice, for Tykoski, the tell-tale signs were the sharp pinching of skull roof bones between enlarged jaw-closing muscles on the top of the skull, as well as teeth much thicker side to side than appear in most other carnivorous dinosaurs, and, a strong peg and socket contact between bones running along the top and side of the snout. Tykoski was even able to determine the fossil's age: The deep peg and socket contact between the bones of the top and sides of the snout only develops in relatively mature tyrannosaurs, he said.

"One can best think of this new species as a 'cousin' to Tyrannosaurus rex," Tykoski told the International Science Times in an interview.  "Both of the analyses we ran, found the new Alaskan species was very closely related to Tyrannosaurus Rex and its closest 'cousin,' Tarbosaurus bataar from north-central Asia." The paleontologists, Anthony R. Fiorillo, and Ronald S.Tykoski  of the Department of Paleontology, Perot Museum of Nature and Science, Dallas, published their results inPLOS One  in an article called, "A Diminutive New Tyrannosaur from the Top of the World," 

The discovery of Nanuqsaurus hoglundi provides new insights into tyrannosaurus adapted and evolved in the ancient Arctic. It's half the size of a T. Rex, an adaptation of many animals to cooler temperatures. The Nanuqsaurus was about six to seven meters long (18 to 20 feet), and about 170 to 175 centimeters tall at the hips (about five feet, nine inches), with a skull about 60 to 70 centimeters long (around 23 to 27 inches).  That's small compared to the largest T. Rex, more than 12 meters long, between three and four meters at the hip, with skulls 150 centimeters  in length.  But smaller doesn't mean nicer. "I very much doubt this was a nice, cuddly animal," Fiorillo said. "This was still the top predator where it lived."

About 70 million years ago, when the Nanuqsaurus roamed, the mean annual temperature in northern Alaska was about the same as the range from modern Oregon to Alberta, Canada - unusually cool and seasonal for a reptile. "It shows us that advanced tyrannosaurs, which were top predators of their time, were more adaptable to more conditions that we had previously thought," Fiorillo said. "The predators adapted over time toward a smaller body size than seen in their closest relatives in response to these pressures." About one to two million years separates Nanuqsaurus from its T. Rex cousin. The Nanuqsaurus predates T. Rex by about  a million to two million years: It dwelled 70-69 million years ago, with the first T. Rex specimens living almost 68 million years ago, to 66 million years ago.

Fiorillo is planning on visiting the site and looking for more Nanu bones. "I would love to go back and collect more but it takes more funding.  I led a small field party back into the area in 2012 and we recovered more bones from different sites so we now know that Nanuqsaurus was more widespread than this one site," he said.

The species name honors one of the founding donors for the Perot Museum of Nature and Science, Forrest Hoglund.  "I wanted the genus name to reflect on the native heritage of the area where we were working," Fiorillo said.  "This new dinosaur was the top predator of the ecosystem in which it lived.  In the modern Arctic, that top predator is arguably the polar bear." The paleontologist used an English-Inupiat online dictionary to find the Inupiat spelling for polar bear, 'nanuq.' The new dinosaur's genus name is Nanuqsaurus, which translates to, 'polar bear lizard.'

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