70-Million-Year-Old Fossil of T.rex Cousin Found in Alaska

Tyrannosaurs rex, which once roamed Asia and North America, had a "pigmy" cousin that lived in Alaska some 70 million years ago, according to scientists. 

Anthony Fiorillo and Ronald S. Tykoski from the Perot Museum of Nature and Science, and colleagues have found dinosaur fossils similar to the iconic T. rex in the Late Cretaceous sediments of Alaska. They've dubbed the newly discovered dinosaur cousin Nanuqsaurus hoglundi.

Tyrannosaurs belong to the lineage of carnivorous theropods, which were monstrous bipedal dinosaurs, some of which were the largest hunters that roamed the Earth. Most of the research conducted on Tyrannosaurs comes from fossils from low-latitudes in North America and Asia.

The current research is based on analysis of skull bones and jaw obtained from Prince Creek Formation in Northern Alaska

The cranial bones showed that Nanuqsaurus hoglundi was closely related with two other tyrannosaurides, Tarbosaurus and Tyrannosaurus, according to the news release.

The dinosaur was smaller than T rex. Its head measured 25 inches in length; T.rex's head was around 60 inches.

N. hoglundi might have lived in high latitude regions of Cretaceous North America.  According to the researchers, its small size could have been an adaptation to survive the arctic cold. Also, N.hoglundi was separated from its other dinosaur cousins due to the presence of Brooks Range. The isolation may have contributed to the diversification of the dinosaur.

According to the researchers, the differences in physical features show that Tyrannosaurs had adapted and evolved to live in Arctic region.

"The 'pygmy tyrannosaur' alone is really cool because it tells us something about what the environment was like in the ancient Arctic," said Fiorillo. "But what makes this discovery even more exciting is thatNanuqsaurus hoglundi also tells us about the biological richness of the ancient polar world during a time when the Earth was very warm compared to today."

The study is published in the journal PLOS One.