Pygmy Dinosaur, Cousin of T. Rex, Roamed the Arctic

By Gemma Tarlach | March 12, 2014 4:00 pm
Less than half the size of the famous T. Rex, pygmy tyrannosaur Nanuqsaurus hoglundi called Cretaceous Alaska home some 70 million years ago. Credit: Illustration by Karen Carr.

Oh the Northern Lights, they shine so bright, and….AAAAAGGGH! About half the size of the famous T. Rex, pygmy tyrannosaur Nanuqsaurus hoglundi called Cretaceous Alaska home 70 million years ago. Credit: Illustration by Karen Carr.

A newly reclassified predator may have been the Napoleon of the dinosaur kingdom—a diminutive tyrant.

Researchers analyzing the partial skull, jaw and teeth of the 70 million year old dinosaur believe the animal was a smaller relative of the famous “King of Tyrants,” Tyrannosaurus Rex.

Nanuqsaurus hoglundi, found in northern Alaska, was initially classified as a different species of carnivorous theropod. However, new analysis suggests it is a previously unknown tyrannosaur that is closely related to T. Rex and to fellow toothy tyrant Tarbosaurus. The new genus name Nanuqsaurus is based on the local word for “polar bear.”

Pygmy Dinosaur

N. hoglundi‘s skull, in adulthood, was estimated by researchers to have been 25 inches long. By comparison, the adult skull of a T. Rex was about 60 inches. It’s likely that the animal’s body length was about half of an adult T. Rex, based on the skull proportions.


Nanuqsaurus hoglundi (A) as compared to T. Rex (B and C) and other species. The scale bar equals 1 meter. Courtesy PLoS.

Researchers believe N. hoglundi‘s smaller size may have been an adaptation to its Arctic environment. Though much warmer than today, the Alaska of the Cretaceous would have still experienced seasonal temperature extremes due to its high latitude—and, consequently, variations in available food sources. The team reported their analysis today in the online open-access journal PLoS One.

The find is important not only for expanding the known range of tyrannosaurs, but also because it provides valuable insight into the fauna of the late Cretaceous Arctic. Previously, tyrannosaurid dinosaurs were found almost exclusively in lower latitudes in Asia and North America, where they were apex predators. N. hoglundi likely was the top of its food chain, too. Finding its fossils in the Prince Creek Formation on Alaska’s North Slope is already rewriting our understanding of the ecology of the northernmost stretches of land during the Late Cretaceous.


CATEGORIZED UNDER: Living World, top posts
MORE ABOUT: dinosaurs, paleontology
  • Ralph Gauer

    Best cutline to an image ever: “Oh the Northern Lights, they shine so bright, and….AAAAAGGGH!”

    • GemmaTarlach

      Thanks, Ralph…I’m not going to say that’s been the highlight of my career, but I was pretty dang pleased with it :-)

      • Ralph Gauer

        Karen liked it too… thought it went with the spirit of the image. Maybe we need to do a movie poster-style version of it with your cutline across the top!

  • disqus_eric

    First image looks like the closer dino photobombed the other.

  • trjc

    Gemma Tarlach:
    In the illustration, you wrote that both B and C are T. Rex. Why then are they different sizes? Is one male and the other female, or one adult and the other an adolescent, or what? Please identify all dinosaurs A-G by type, sex, and by whatever makes B and C different, that is assuming it is not sex.

    Thank you.

    • J. Preposterice

      You could always go look up the caption on the original illo. Here, I’ve done it for you:

      Silhouettes showing approximate sizes of representative theropods. A, Nanuqsaurus hoglundi, based on holotype, DMNH 21461. B, Tyrannosaurus rex, based on FMNH PR2081. C, Tyrannosaurus rex, based on AMNH 5027. D, Daspletosaurus torosus, based on FMNH PR308; E, Albertosaurus sarcophagus, based on TMP 81.10.1; F,Troodon formosus, lower latitude individual based on multiple sources and size estimates; G, Troodon sp., North Slope individual based on extrapolation from measurements of multiple dental specimens [47]. Scale bar equals 1 m.


      • GemmaTarlach

        Thanks for replying on my behalf, J. I’m having some trouble with Disqus comments showing up in my feed and am just seeing trjc’s question now. And just to clarify, the editor who wrote that particular cutline (not me, in this case) opted to leave out some of the less-relevant identifying details because, while the Plos ONE paper deals with the find in much greater depth, recapping everything would have made for one very long D-Brief (and a very long cutline). That’s why we always link to the paper in our D-Brief; if it’s a topic you’re interested in, reading the original paper is the best way to get the full picture. Cheers!


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