In a study published Wednesday in PLoS One, paleontologists Anthony Fiorillo and Ronald Tykoski of Dallas, Texas’ Perot Museum of Nature and Science have named a diminutive tyrannosaur that once trod beneath the Arctic’s northern lights.
The researchers have dubbed the dinosaur Nanuqsaurus hoglundi – a title combining the Iñupiaq word for polar bear with a species name honoring geologically-minded philanthropist Forrest Hoglund.
Bones of the tyrannosaur were recovered at the Kikak-Tegoseak Quarry on Alaska’s North Slope. Even with continental shifts since the Cretaceous, the site would have been within the Arctic Circle during the heyday of Nanuqsaurus.
Relatively little of the dinosaur has been found so far. The material Fiorillo and Tykoski drew upon to name the dinosaur consists of disarticulated skull bones, including parts of the skull roof and the jaws. Some of these bones were previously thought to belong to the classic tyrannosaurs Albertosaurus and Gorgosaurus, but the new analysis by Fiorillo and Tykoski found that the North Slope fossils differ in the arrangement of the bones on the skull roof and the size of the tooth sockets. And since some of the skull bones are fused, this Nanuqsaurus was likely at or approaching adult size.
Size matters, in this case, because the most immediately striking aspect of Nanuqsaurus is the tyrannosaur’s small size. Using other tyrannosaur skulls as a guide, Fiorillo and Tykoski hypothesize that the skull of a mature Nanuqsaurus was not much more than two feet long. The skull of the largest known T. rex – the biggest known tyrannosaurs – were about five feet long. Likewise, at an estimated 25 feet long, Nanuqsaurus could have stood in the shadow of a 40-foot-long T. rex.
Still, despite the size difference, T. rex and Nanuqsaurus were relatively close relatives.