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Darwin's Mystery Animals

The origins of the  Macrauchenia, an extinct mammal, have been poorly understood for years.

The Macrauchenia is not an animal that many people have heard of.

It's an extinct mammal that has a body like a humpless camel, the feet of a rhinoceros, and a snorkel-like nose about half as long as an elephant's.

Charles Darwin said it was one of the strangest animals ever discovered. Scientists suspected it was some type of South American ungulate, but weren't quite sure what it was. Ungulates are animals that have hooves. If the Macrauchenia was an ungulate, it would mean it was related to camels and deer.

For many years, the precise origin and nature of the Macrauchenia remained obscure. Scientists thought that South America's ungulates, who all disappeared about ten thousand years ago, were related to mammals such as horses rather than elephants and other species. The trouble was, the available fossils didn't contain any good DNA for comparison.

Ancient Collagen

Instead of DNA, they decided to compare samples of collagen instead. It's a structural protein found in all animal bones that can survive for eons under all sorts of conditions, up to ten times longer than DNA. The directions to make collagen come from the DNA, so each species has its own distinct collagen built from a series of smaller pieces called amino acids.

The scientists compared the collagen of living and extinct species. They used a variety of fossil samples, including two discovered by Darwin. They found that Macrauchenia is most closely related to horses, rhinos, and tapirs. They also confirmed that their ancestors moved from North to South America over sixty million years ago.

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