Wednesday, 30 September 2015

A New Species Of Polar Dinosaur

The world of the polar dinosaurs, with Ugrunaaluk
dominating the scene
Walking with Dinosaurs presented a striking image of the world of polar dinosaurs. During the Mesozoic the Earth's climate was warmer and instead of ice sheets, the poles were covered in seasonal forests. Small tribes of Leaellynasaura roamed the undergrowth, sheltering from polar predators and hibernating through the winter.

Debate over the nature of polar dinosaurs continues, particularly regarding whether they were warm or cold blooded. Reptiles are cold blooded and so require an external heat source such as the sun. Yet how cold blooded dinosaurs could have survived in periodically cool conditions is unclear.  

Since this landmark documentary our knowledge of polar dinosaurs, and dinosaur physiology in general, has increased greatly. Now another new species of polar dinosaur has been discovered. 'This new study names and brings to life what is now the most completely known species of dinosaur from the Polar Regions,' said Patrick Druckenmiller from the University of Alaska Fairbanks. Since the 1980s, palaeontologists from a number of institutions have collected over 9000 bones belonging to a variety of creatures from the Prince Creek Formation in Alaska. One particular layer, the Liscomb bone bed, yielded a multitude of specimens of a single dinosaur species.

A skull of the 69 million year old Alaskan
hadrosaurid Ugrunaaluk kuukpikensis
The researchers identified them as belonging to a new species, Ugrunaaluk kuukpikensis, derived from the Iñupiaq Inuit words for ancient grazer.

'Because many of the bones from our Alaskan species were from younger individuals. A challenge of this study was figuring out if the differences with other hadrosaurs was just because they were young or if they were really a different species,' said Druckenmiller. 'Fortunately, we also had bones from older animals that helped us realize Ugrunaaluk was a totally new animal.'

Further anatomical study showed that it was most closely related to the duck-billed hadrosaur Edmontosaurus.

The young age of most of the individuals suggested that a young herd was wiped out in a sudden event, leading to their preservation in a single bone bed. While the event is unknown, the area where they lived was harsh. The site today lies within the Arctic circle. 69 million years ago, when the bone bed formed, the site was at a similarly high latitude. While global temperatures were generally higher, the environment would still have experienced seasonal icy spells and winter darkness.

'What we're finding is basically this lost world of dinosaurs with many new forms completely new to science,' said Greg Erickson from Florida State University.