Paleontologists have uncovered the fossilized jawbone of a juvenile dromaeosaurid (raptor) dinosaur that lived 70 million years ago in what is now northern Alaska.

Life reconstruction of the Alaskan saurornitholestine dinosaur in its environment. Image credit: Andrey Atuchin.

Dromaeosauridae is a group of small to medium-sized feathered predatory dinosaurs that flourished in the Cretaceous period.

These dinosaurs lived all over the world, but their bones are often small and delicate and rarely preserve well in the fossil record, complicating efforts to understand the paths they took as they dispersed between continents.

North American dromaeosaurids are thought to trace their origins to Asia, and Alaska would have been a key region for the dispersal of their ancestors.

The new fossil is a tantalizing clue toward understanding what kinds of dromaeosaurs inhabited this crucial region.

“There are places where dinosaur fossils are so common that a scrap of bone, in most cases, cannot really add anything scientifically informative anymore,” said lead author Dr. Alfio Alessandro Chiarenza, a paleontologist at the Imperial College London.

“This is not the case with this Alaskan specimen.”

“Even with such an incomplete jaw fragment, we were not only able to work out the evolutionary relationships of this dinosaur, but also to picture something more on the biology of these animals, ultimately gaining more information on this ancient Arctic ecosystem.”

The fossilized jawbone of the Alaskan saurornitholestine dinosaur. Image credit: A. Chiarenza.

The dromaeosaurid jawbone, which is 1.4 cm long and preserves the tip of the lower jaw and two teeth, was collected from exposures of the Prince Creek Formation in northern Alaska.

Based on tooth shape and other characteristics, Dr. Chiarenza and colleagues attributed the fossil to a saurornitholestine dromaeosaurid.

The early developmental stage of the specimen suggests this individual was still young and was likely born nearby.

“This study of a predatory dinosaur jaw from a baby provides the first physical proof that at least some dinosaurs not only lived in the far north, but they thrived there,” said co-author Dr. Anthony Fiorillo, a researcher at Southern Methodist University.

“One might even say, our study shows that the ancient north was a great place to raise a family and now we have to figure out why.”

“This is the first confirmed non-dental fossil specimen from a member of Dromaeosauridae in the Arctic, expanding on the role of Beringia as a dispersal route for this clade between Asia and North America,” the paleontologists said.

“Furthermore, the juvenile nature of this individual adds to a growing body of data that suggests Cretaceous Arctic dinosaurs of Alaska did not undergo long-distance migration, but rather they were year-round residents of these paleopolar latitudes.”

Source: sci.news