One of the smallest tyrannosaurids ever found and a new species of North American tyrannosaurid was reported by Anthony Fiorillo and Ronald S. Tykoski from the Perot Museum of Nature and Science in Dallas, Texas in the March 12, 2014, edition of the journal Public Library of Science.
The jaw, maxilla, and partial skull were found in Prince Creek Formation in Alaska. The new species named Nanuqsaurus hoglundi provided sufficient evidence for the paleontologists to conclude that the animal was a relative of both Tarbosaurus and Tyrannosaurus, the only known species of tyrannosaurid.
Nanuqsaurus hoglundi was much smaller than it's relative. The dinosaur was about 40 percent of the size of Tyrannosaurus rex based on comparative skull measurements. The fossils are 70 million years old.
The high-altitude and northern climate may be responsible for the difference in size according to the scientists. The location at the northernmost edge of Cretaceous North America may also play a factor in the size of this new species. The isolation of this species of tyrannosaurid by mountains in every direction may have played a part in the animal’s relative small size.
Nanuqsaurus hoglundi is still quite large for an animal and is assumed to have been the top predator in the area during the time that it lived.