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This artist illustration provided by the Perot Museum of Nature and Science in Dallas, Texas, shows a possible new species of dinosaur that has been named Nanuqsaurus hoglundi, and described as akin to a pygmy Tyrannosaurus rex.

Karen Carr , Perot Museum of Nature and Science via Associated Press

Dr. Tony Fiorillo was shown at the excavation site on Alaska’s North Slope where paleontologists discovered a new species of dinosaur that’s described as akin to a pygmy Tyrannosaurus rex.

Perot Museum of Nature and Science via Associated Press,

This artist illustration provided by the Perot Museum of Nature and Science in Dallas, Texas, shows a possible new species of dinosaur that has been named Nanuqsaurus hoglundi, and described as akin to a pygmy Tyrannosaurus rex. The Perot Museum of Nature and Science reports that it discovered the new species in Alaska's North Slope. Perot earth sciences curator Anthony Fiorillo and fossil preparatory Ronald Tykoski say the reptile is a "pint-sized cousin" to the T. rex., weighing just a half-ton and coming in about half the length of its ferocious relative. (AP Photo/Perot Museum of Nature and Science, Karen Carr)

Karen Carr • Perot Museum of Nature and Science via Associated Press,

Tiny-saurus rex prowled the Arctic

  • Article by: Amina Khan
  • Los Angeles Times
  • March 22, 2014 - 10:19 PM

Paleontologists have dug up a fearsome new dinosaur in a surprising place: Nanuqsaurus, a pygmy tyrannosaur that lived far away from its larger sharped-toothed cousins — in what is now northern Alaska.

The newly named Nanuqsaurus hoglundi fossil, described in PLoS ONE, reveals that dinosaurs lived in the Arctic 70 million years ago, during a much warmer period in Earth’s history.

“The discovery of Nanuqsaurus hoglundi provides new insights into tyrannosaurid adaptability and evolution in an ancient greenhouse Arctic,” wrote Anthony Fiorillo and Ronald Tykoski of the Perot Museum of Nature and Science in Dallas.

Nanuqsaurus hoglundi may have been pint-size compared with its well-known cousin Tyrannosaurus rex, but it was still a fearsome animal with a skull that stretched 25 inches. That’s small compared with T. rex’s skull, which was 5 feet long.

It was slightly more than half the length of its more famous cousin, but only about one-fifteenth as heavy. “It would have been a skinnier and a little more graceful version of the Tyrannosaurus rex,” Tykoski said. But probably no easier to get along with. “It was a top predator. I don’t know of any tyrannosaur that you could call cuddly,” he said.

The fossil fragments of upper jawbone, lower jaw- bone, skull roof and braincase were dug out of the Prince Creek Formation on Alaska’s North Slope. This is highly unusual, given that most Tyrannosaur fossils are unearthed around or below southern Canada and central Asia, much closer to the equator.

Tony Fiorillo, the Perot’s curator of earth science, found the remains in 2006 during the same expedition that uncovered the remains of the previously unknown horned dinosaur, Pachyrhinosaurs perotorum, named after the Perot family. Unlike the Perot dinosaur, which was painstakingly excavated from the soil, the N. hoglundi skull was found on the surface, encased in a rock the size of a football.

The football-size rock, however, was not an immediate priority as Fiorillo and Tykoski worked on the Perot dinosaur.

Tykoski said that as he cleaned 70 million years of dirt from the skull, he only gradually realized he had something entirely new to paleontology. It was clear the skull belonged to an adult tyrannosaur, but one with impossibly small teeth.

After eliminating other possibilities, Fiorillo and Tykoski announced that they had found a new genus and species. “Nanuqsaurus” means “polar bear lizard” in the language of the Inupiat people of Alaska’s North Slope. “Hoglundi” refers to Forrest Hoglund, the Texas philanthropist who raised $185 million to build the Perot Museum.

The bones seemed to be a weird mashup of characteristics of different tyrannosaurid species and didn’t fit into the right time frame to be a species like T. rex or Daspletosaurus torosus.

Around this time, 70 million years ago, North America was divided into eastern and western continents by the Western Interior Seaway, which cut off many dinosaur populations. The east-west trending Brooks Mountain range may have further separated some northern and southern populations in the western continent (known as Laramidia). Over time, this isolation probably allowed many species to differentiate and may have accounted for the diversity of Tyrannosaurs. Nanuqsaurus would be no exception.

The pygmy tyrannosaur was probably about 25 feet long and weighed perhaps 1,000 pounds. A typical T. rex was about 40 feet long and weighed up to 8 tons.

The researchers think that Nanuqsaurus was small because it lived so far north and in areas that were far less dependably warm year-round than the areas closer to the equator. Of course, Alaska was probably pretty cozy back in the late Cretaceious Period — more Calgary than Klondike — but it also had seasonal swings, and the winters were probably much more difficult times to find food. And in times of scarcity, a big animal is much harder to feed than a little one. Hence Nanuqsaurus’ size: It was a way to deal with these seasonal swings.

“The smaller body size of Nanuqsaurus hoglundi may reflect that in the profoundly seasonal ancient Arctic environment where the widely varying light regime affected biological productivity, resource availability was limited,” researchers said.

The Dallas Morning News contributed to this report.



 

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