Sunday 26 May 2013

A Giant Camel from the mid-Pliocene of Ellesmere Island in the Canadian Arctic.

Modern Camels are found from Central Asia to North Africa, their closest relatives, the Llamas, are found in South America only. The oldest fossil Camels are found in North America around 45 million years ago; the Llamas probably split from the Camels around 17 million years ago, dispersing into South America by about 3 million years ago. The oldest known Eurasian Camel is a 7 million year old fossil from Spain. It is likely that Camels dispersed from North America to Eurasia via the High Arctic, where a number of fossil Camels have been found.

In a paper published in the journal Nature Communications on 5 March 2013 a team of scientists led by Natalia Rybczynski of the Department of Palaeobiology at the Canadian Museum of Nature describe the discovery of mid-Pliocene fragmentary Camel remains from Ellesmere Island in the Canadian High Arctic, the most northerly Camel remains found to date.

Map showing the location of the Ellesmere Island Camel and the previous most northerly Camel, the Giant Yukon Camel. The arrow points to the Bering Straights, across which Camels are thought to have migrated into Eurasia. Rybczynski et al. (2013).

Prior to this discovery the northernmost known Camel remains were the Yukon Giant Camel (Paracamelus sp.) remains from Plio-Pleistocene deposits of the Old Crow Basin.

The new remains are extremely fragmentary, and were only identified as Camel remains by collagen fingerprinting, a method that extracts collagen peptide markers to identify the taxa of ancient animals. This revealed that the specimen was a Camel, prompting the the researchers to analyze other members of the family to attempt to determine the closest relative the specimen, which revealed that it appeared to be the same species as the Yukon specimen.

Arctic Camel remains. (a) Remains of the right tibia of a Giant Camel from Ellesmere Island, shown against the tibia of an extant Camel (Camelus dromedaries) scaled up to the same size. Scale bar is 10 cm. (b) Upper left second molar of a Giant Camel from the Yukon in lateral view. (c) The same tooth in occlusal view. (d) Lower right second molar of a Giant Camel from the Yukon. (e) First proximal phalanx of a Yukon Camel in posterior view. Rybczynski et al. (2013).

The sample was dated to about 3 million years ago using terrestrial in situ cosmogenic nuclide (TCN) burial dating, which measures how long ago objects were exposed to cosmic rays at the surface. This places the sample in the mid-Pliocene, when global temperatures were 2-3℃ higher than they are now. The formation where the Camel was found is thought to represent a mixture of boreal forests and wetlands, with a mean average temperature of  1.4 ± 4.0℃, at least 18℃ degrees warmer than today. The deposits have revealed a number of other mammal fossils, including Deer, Horses, Rabbits, Beavers and a variety of carnivores.

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