A 33 million year old fossilised skeleton of a turtle is set to go under the hammer in London this month.

The ancient creature roamed the world in the Oligocene epoch at the end of the Paleogene Period.

At the time it became buried the composition of the earth was vastly different and that area of land enjoyed warmer temperatures, making it a suitable habitat for turtles.

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The turtle (pictured) was unearthed in an area of South Dakota known as the White River Badlands about five years ago and is now being sold at Christie's auction house

ANCIENT TURTLE Scientific tests carried out after its excavation found it to be of the now extinct Stylemys genus. Stylemys lived in temperate and subtropical areas of North America, Europe and Asia. It was common in the prehistoric Badlands in the US - notably Nebraska and South Dakota. The turtle was common in the prehistoric Badlands in the US - notably Nebraska and South Dakota. Unlike modern turtles, stylemys had primate jaw muscles and would have been herbivorous. Advertisement

This ancient reptile was unearthed in an area of South Dakota known as the White River Badlands about five years ago.

Scientific tests carried out after its excavation found it to be of the now extinct Stylemys genus, which lived in temperate and subtropical areas of North America, Europe and Asia.

Since then it has been in the hands of a private collector, who is now selling it through Christie's auction house, which estimates it to be worth up to £3,500 ($4,340).

The turtle was common in the prehistoric Badlands in the US - notably Nebraska and South Dakota.

Unlike modern turtles, stylemys had primate jaw muscles and would have been herbivorous.

James Hyslop, head of the auction house's science department, said: 'Fossilisation depends on a very rare set of circumstances so it's very unusual for it to occur, especially in turtles.

'Most animals that die are scavenged and ripped apart by others but this one clearly sunk into the ground without that happening.

'Then over the course of millions of years it got buried deeper and deeper until eventually becoming a fossil.

Scientific tests carried out after its excavation found it to be of the now extinct Stylemys genus, which lived in temperate and subtropical areas of North America, Europe and Asia

Scientific tests carried out after its excavation from the White River Badlands found it to be of the now extinct Stylemys genus, which lived in areas of North America, Europe and Asia

Fossilisation occurs over time as sediment covers the remains, causing the bones, teeth and shell to become encased.

'And miraculously all these years later the remains are dug back up, although in this case we're not entirely sure how that came about', said Mr Hyslop.

'There is a strong market for fossils and we expect something of this quality and age to attract significant interest at auction', he said.

After thousands of years the remaining body parts dissolve and are replaced with rock-like minerals, which in this case is limestone.

This process results in a fossil which is a like for like copy of the original object.

The fossilised turtle, weighing around 4lbs (2kg), will be sold in London on April 27.