Collagen Helps Scientists Locate Darwin's Mysterious South American Beasts on Tree of Life

After nearly two centuries, scientists claim to have found the right place on the evolutionary tree for Darwin's mysterious South American beasts.

The fossils of ungulates Toxodon and Macrauchenia which went extinct 10,000 years ago were collected by Charles Darwin during his HMS Beagle voyage to South America in 1839. Darwin is said to have called termed them 'strangest animals ever discovered' and researchers have since struggled with placement on the family tree. The quest has seen scientists related them to elephants, aardvarks, sloths and even armadillos.

Now, scientists have found that the two animals belong to a group related to horses, rhinos and tapirs. This conclusion was made when scientists extracted collagen from the fossils and compared them with that of living animals. Toxodon is believed to have the built of a rhino with a hippopotamus's head, while Macrauchenia is a llama like creature with an anteater's snout.

The discovery is being hailed for its methods. While such finds are usually reported following DNA analysis, DNA is not always available in fossils. Proteins like collagen on the other hand, can last much longer.

"The problem is not a lack of fossils - there are thousands of South American-native ungulate fossils in museums in many countries - nor is it a lack of ideas and possible explanations. Rather, the fundamental problem is that South American-native ungulates display detailed resemblances to a whole range of non-South American groups," Ross MacPhee, a curator at New York's American Museum of Natural History, told Live Science.