A group of paleontologists has announced the discovery of fossilized remains of an extinct giant camel that lived in what is now Canada about 3.5 million years ago.
Illustration of the High Arctic camel on Ellesmere Island during the Pliocene warm period, about 3.5 million years ago (© Julius Csotonyi)
The discovery, described in the journal Nature Communications, is based on 30 fossil fragments of a leg bone found on Ellesmere Island, and represents the most northerly record for early camels, whose ancestors are known to have originated in North America some 45 million years ago.
The fossils are about 3.5 million years old (mid-Pliocene). Other fossil finds at the site suggest this High Arctic camel lived in a boreal-type forest environment, during a global warm phase on the planet.
“This is an important discovery because it provides the first evidence of camels living in the High Arctic region,” said lead author Dr Natalia Rybczynski from the Canadian Museum of Nature. “It extends the previous range of camels in North America northward by about 1,200 km, and suggests that the lineage that gave rise to modern camels may been originally adapted to living in an Arctic forest environment.”
The camel bones were collected from a steep slope at the Fyles Leaf Bed site, a sandy deposit near Strathcona Fiord on Ellesmere Island. Fossils of leaves, wood and other plant material have been found at this site, but the camel is the first mammal recovered. A nearby fossil-rich locality at Strathcona Fiord, known as the Beaver Pond site, has previously yielded fossils of other mammals from the same time period, including a badger, deerlet, beaver and three-toed horse.
“The first time I picked up a piece, I thought that it might be wood. It was only back at the field camp that I was able to ascertain it was not only bone, but also from a fossil mammal larger than anything we had seen so far from the deposits,” Dr Rybczynski said.
Some important physical characteristics suggested the fossil fragments were part of a large tibia, the main lower-leg bone in mammals, and that they belonged to the group of cloven-hoofed animals known as arteriodactyls, which includes cows, pigs and camels. Digital files of each of the 30 bone fragments were produced using a 3D laser scanner, allowing for the pieces to be assembled and aligned. The size of the reconstituted leg bone suggested it was from a very large mammal. At the time in North America, the largest arteriodactyls were camels.
Full confirmation that the bones belonged to a camel came from a new technique called ‘collagen fingerprinting’ pioneered by Dr Mike Buckley at the University of Manchester in England. Profiles produced by this technique can be used to distinguish between groups of mammals.
Fossil bones of the High Arctic camel (© Martin Lipman)
The collagen profile for the High Arctic camel most closely matched those of modern camels, specifically dromedaries (camels with one hump) as well as the Yukon giant camel, which is thought to be Paracamelus, the ancestor of modern camels. The collagen information, combined with the anatomical data, allowed the group to conclude that the Ellesmere bones belong to a camel, and is likely the same lineage as Paracamelus.
“We now have a new fossil record to better understand camel evolution, since our research shows that the Paracamelus lineage inhabited northern North America for millions of years, and the simplest explanation for this pattern would be that Paracamelus originated there. So perhaps some specializations seen in modern camels, such as their wide flat feet, large eyes and humps for fat may be adaptations derived from living in a polar environment.”
The group also reports for the first time an accurate age of both the Fyles Leaf Bed site and the Beaver Pond site – at least 3.4 million years old.
______
Bibliographic information: Natalia Rybczynski et al. 2013. Mid-Pliocene warm-period deposits in the High Arctic yield insight into camel evolution. Nature Communications 4, article number: 1550; doi: 10.1038/ncomms2516
