Baby raptor discovered in Alaska may have been a permanent resident of the ancient Arctic

Analysis of the tip of a fossilized jawbone, just 14 millimeters long, found in northern Alaska, showed that the creature was a type of dromaeosaurid, a group of predatory dinosaurs closely related to birds, whose members include the Velociraptor, the dinosaurs that terrorized in "Jurassic Park."

The jawbone would have been from a young dinosaur chick, and the early developmental stage of the bone suggests it was born nearby.

Many paleontologists believe the Arctic was a migration path for many types of dinosaur when they crossed between Asia and North America, but so far there's been little evidence found to suggest that the animals lived there year in, year out.

"If juveniles from these dinosaurs are being found, it means that these animals had to spend a great deal of time mating and nesting in these sites," said Tony Fiorillo, a paleontologist at Southern Methodist University in Texas and chief curator of the Perot Museum of Nature and Science.

"A young chick for these small dinosaurs could probably not migrate long distance, giving indirect indication that these animals were probably perennial residents of the ancient Arctic."

The baby dinosaur would have been the size of a small puppy, Fiorillo said, but fully grown dromaeosaurids can range from 6 to 9 feet. By comparison, to withstand the rigors of migration, modern caribou need to be at least 80% of its adult length, he said.

The study was published in the journal PLOS ONE.

Dromaeosaurids lived all over the world, but their bones are often small and delicate and have not been preserved well in the fossil record, the study said, complicating efforts to understand the paths they took as they spread across continents.

The partial jaw fossil, with one black erupted tooth, was found on a bank of the Colville River near the Arctic Ocean, about 250 miles north of the Arctic Circle. It's part of the Prince Creek Formation of northern Alaska, which preserves the largest collection of polar dinosaur fossils in the world, dating to about 70 million years ago.

"What is extraordinary about this finding is that not only bones from carnivorous dinosaurs are rarely found in these sites, but discovering one from a very young individual, which can easily get broken up, destroyed and then not entering the fossil record is like finding a needle in the haystack," said lead author of the study Alessandro Chiarenza, a paleontologist at University College London.

He said a more complete skeleton was needed to confirm it was a completely new species of dromaeosaurid.

Seventy million years ago, the Arctic would have been warmer than it is now -- with a climate similar to Seattle's or Portland's and a rich environment of conifers, mosses and ferns. However, winter temperatures might have dropped to 14 degrees Fahrenheit (-10 degrees Celsius), said Chiarenza, and the creatures would have had to contend with up to four months of winter darkness that could have affected their bone growth.

In the past, it was considered unlikely that dinosaurs, which were regarded as big, cold-blooded lizards, would live in cold conditions, he added.

"Now we know that they probably had more bird-like metabolisms and adaptations, allowing them to survive harsher environments, and for herbivorous dinosaurs to survive on a lower supply of fodder," he said.

The baby raptor may have fed on a thumb-size marsupial called Unnuakomys or the tiny mammal Cimolodon, the study said. Their fossils have been found in the Arctic region.