The oldest remains of a polar bear ever discovered

The oldest remains of a polar bear ever discovered

Top image: The subfossil left mandible of a polar bear found in Svalbard in 2004 is well preserved. Photo: Ólafur Ingólfsson/UNIS.

The polar bear jawbone discovered at Prins Karls Forland during a UNIS course excursion in 2004, is now confirmed to be the oldest remains of a polar bear ever found. Dating of the Svalbard fossil suggests it is between 130-110 000 years old.

5 January 2010
Text: Eva Therese Jenssen/UNIS.

During a UNIS geology excursion at Poolepynten at Prins Karls Forland in the summer of 2004, the students and staff found a well preserved subfossil left mandible of a polar bear.

Rare find
As fossil finds of polar bears are few and far between, the evolutionary history of the largest of the bear species is not very well known. The scarceness of polar bear fossils can most likely be attributed to the fact that polar bears for the most part live and die on the pack ice, making fossil finds in terrestrial sediments exceptional.

The Poolepynten mandible was dated at the Lund University Dating Laboratory, Sweden. The 14C age determination shows that it is older than 45 000 years, and an age determination with infrared-stimulated luminescence, together with the stratigraphic position of the bone, suggests that it is 130-110 000 years old (Eemian-Early Weichselian age).

This makes the Poolepynten jawbone the oldest remains of a polar bear ever discovered, according to a recent published article by professor Ólafur Ingólfsson (University of Iceland and UNIS) and Professor Øystein Wiig (University of Oslo).

Fossil from a fully grown male polar bear
When the news about the find was first made public in 2007 it was believed that the jawbone was from a female polar bear. Further analyses now suggest that the mandible instead is that of a fully grown male polar bear, similar in size to grown male polar bears of today.

Other analyses indicates that the sediment in which the jawbone was found, was deposited during a period of high relative sea levels, subsequent to a regional deglaciation, suggesting advection of relatively warm, North Atlantic water to the site at the time of the deposition.

The jawbone is exceptionally well preserved, probably due to a combination of burial in fine-grained marine sediments and preservation for a long time under permafrost condition.

This opens up the possibility of further analyses of the fossil, possibly revealing ancient mitochondrial DNA (mtDNA) and carbon isotope composition, that may reveal more details on the evolutionary history of polar bears. This work is in progress, according to professor Ingólfsson.

Reference:
Ingólfsson, Ólafur and Wiig, Øystein: Late Pleistocene fossil find in Svalbard: the oldest remains of a polar bear (Ursus maritimus Phipps, 1744) ever discovered. Polar Research, Volume 28, Issue 3 (December 2009), pp. 455-462. DOI: 10.1111/j.1751-8369.2008.00087.x

 

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