Genetics «resurrected» DNA of a prehistoric «riddles Darwin»

© Jorge Blanco as the artist imagined macrauchenia, prehistoric mysteries Darwin from South AmericaGenetics «resurrected» DNA of a prehistoric «riddles Darwin»© Jorge Blanco

. Mysterious macrauchenia that resembled a cross between camels, llamas and elephants were close relatives of horses, rhinos and tapirs, say scientists decode the DNA of this relic of the ice age from South America and published their findings in the journal Nature Communications.

«Macrauchenia no living relatives whose genomes usually help us in the reconstruction of DNA extracted from bones of prehistoric animals, containing a lot of damage and contaminated by «foreign» genetic code. So we had to develop a new method of multistage recovery of DNA using the genomes of several other animal species,» says Michael Westbury (Westbury Michael) from the University of Potsdam (Germany).

Macrauchenia and their distant relatives toxodon were discovered by Charles Darwin in 1834 during excavations on the territory of Patagonia, the southern region of Argentina. Here a British scientist managed to open the remains of several species of hoofed mammals, which he called «the most amazing creatures» on the Earth and could not understand whose relatives they are.

In the subsequent 180 years, hundreds of other paleontologists and biologists have tried to resolve this «mystery of Darwin», including Richard Owen, one of the founding fathers of paleontology, and not reached in this matter better than the author of the theory of evolution. These failures were associated with an extremely unusual appearance macrauchenia and toxodon – the first one looked like a giant llama with a trunk, and one on the stocky herbivorous bear or Hippo with a length of three meters and the height of a man.

Westbury and his colleagues have solved this mystery, using the methods of modern paleogenetic to «resurrect» the DNA of long-extinct animals by fragments of the genome that is conserved within their bones or teeth.

To solve this problem, in addition to «bezrodnoy» themselves Marubeni and Toktogonov, it was difficult for another reason – in the tropics and at the equator, the remains of DNA very quickly washed out and disappear from the bones of ancient animals. The majority of the genomes of ancient humans and animals was obtained from the study of remains recovered from a permafrost or soil caves of the temperate zone.

How to tell the scientists, they were lucky in this respect – they managed to find the remains of Marubeni in one of the mountain caves in Chile, which has developed conditions favorable for preservation of DNA.

Despite this, geneticists were able to extract and recover only a small part of the genome of these ancient creatures, the so-called mitochondrial DNA. This part of the genome is not contained within the cell nucleus and in the mitochondria – the cellular power stations, transmitted from mother to her offspring along with the egg. This part of the genome changes relatively slowly, which allows scientists to trace the family ties between individual Nations, and even groups of animals.

For this reason, even 80% of mitochondrial DNA Marubeni enough to prove that these animals are not relatives of the llamas, as originally believed, Richard Owen, and close relatives of animals equids such as horses, rhinos and tapirs.

The ancestors of cloven-hoofed animals and Marubeni, as shown by genetic analysis, were divided long ago, about 65 million years ago, at a time when dinosaurs disappeared from the face of the Earth after the fall of the asteroid on the modern Yucatan Peninsula. Accordingly, it is now possible to say that «Darwin’s Enigma» was finally resolved, and that Marubeni and toxodon has taken its rightful place on the tree of evolution of life.

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