Everyone is familiar with Tyrannosaurus rex, but humanity is only now meeting its much smaller Arctic cousin.
Scientists have announced the discovery of a new genus and species of dinosaur, based on remains found in Alaska. They are calling the species Nanuqsaurus hoglundi.
This dinosaur lived about 70 million years ago, say paleontologists Anthony Fiorillo and Ronald Tykoski, at the Perot Museum of Nature and Science in Dallas. Their study, published in the journal PLOS One, is aptly called "A Diminutive New Tyrannosaur from the Top of the World."
Researchers discovered the dinosaur's remains in 2006 in the Prince Creek Formation on Alaska's North Slope. At the same quarry, Fiorillo and Tykoski have previously uncovered other important finds, such as remnants of the horned dinosaur species Pachyrhinosaurs perotorum, whose discovery was announced in 2011.
"I find it absolutely thrilling that there is another new dinosaur found in the polar region," Fiorillo said in a statement from the Perot Museum. "It tells us that the ecosystem of ancient Arctic was a very different place, and it challenges everything we know about dinosaurs."
What scientists know about Nanuqsaurus hoglundi comes from just a few fragments: The top part of a skull section, part of a lower jaw, and part of an upper facial jawbone.
"Nanuqsaurus" loosely translates to "polar bear lizard," according to the Perot Museum, and honors the Inupiat people whose territory traditionally includes where the dinosaur remnants were found. The "hoglundi" part honors Dallas entrepreneur and philanthropist Forrest Hoglund.
A Tyrannosaurus rex would have weighed between 7 and 8 tons, with a length of about 40 feet. By comparison, an adult Nanuqsaurus might have been only 25 feet long, with a weight of 1,000 pounds. The head was probably about 2 feet long, CNN affiliate WFAA reported.
"There were features in these specimens that were unique; you didn't see them in other tyrannosaurs," Tykoski told WFAA.
Study authors told the Perot Museum that the dinosaur may have been so small because of how isolated the area was, and how little food was likely available. At that time, planet Earth as a whole was warmer than it is today, but this particular area in Alaska would have been dark about half the year.
"Conditions in this setting were relatively warm, but there were profound to extreme seasonal changes in light regime throughout the year that would have limited resource availability and produced substantial variance in temperatures," study authors wrote.
We know of other animals have clearly adapted to their environments by evolving in size over time, such as large Russian Arctic mammoths that evolved to be cow-sized.
But why was this particular dinosaur, Nanuqsaurus hoglundi, living so far north on the globe? Scientists have many more such questions to explore.
In terms of investigating this polar region for more clues, as Fiorillo put it, this is just the tip of the iceberg.