Ancient DNA Solves The Mystery Of An Animal That Totally Baffled Darwin
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DARWIN WAS STUMPED WHEN HE DISCOVERED THE FOSSILS OF A BIZARRE ICE AGE MAMMAL. NOW, WE'VE FINALLY FOUND ITS PLACE ON THE EVOLUTIONARY TREE. WELLCOME TRUST/WIKIMEDIA COMMONS
By Tom Hale
Darwin was stumped when he discovered the fossils of a bizarre Ice Age animal in 1834 during his famous voyages on the HMS Beagle. With the limited amount of bones available, even his great mind couldn't figure out what group of animal this specimen belonged to. Years later, the bones were passed on to renowned paleontologist Richard Owen for him to figure out, but still no dice. Over 180 years later and the mystery remained, until now.
A new study has reconstructed the DNA of this strange creature to finally place it on the evolutionary tree. The research, led by the University of Potsdam, was recently published in the journal Nature Communications.
The animal in question is Macrauchenia patachonica, a mammal that's believed to have gone extinct in South America between 20,000 and 10,000 years ago, when it suddenly disappeared from the fossil record. It’s a long-necked, long-limbed mammal that looks a bit like a mash-up of a camel, a giraffe, and an elephant straight out of a fantasy film for kids. But despite these vague similarities to well-known animals, the M. patachonica did not have any close living relatives, making its identification very tricky indeed.
This new project gathered bone samples collected across South America and extracted the mitochondrial DNA from its ancient collagen protein. The team discovered that it actually belongs to a lineage that split from Perissodactyla, an order of odd-toed ungulates that includes horses, rhinos, and tapirs. The two groups are thought to have diverged about 66 million years ago.
"We now have found a place in the tree of life for this group, so we can now also better explain how the peculiarities of these animals evolved," Michi Hofreiter, lead author and paleogenomics expert at the University of Potsdam, told CNN.
Sequencing the DNA was no small feat, however. DNA tends to degrade over the years, especially if it's kept in a warm climate for thousands of years. The researchers effectively had to piece together the DNA from short sequences of genetic material from numerous different individuals. This was made all the tougher because the animal has no close living relatives for the researchers to “fill in the missing spaces”.
“Paleontologists until modern days have been confused by these animals," Hofreiter told Gizmodo. "Reconstructing a reliable sequence from these short DNA segments with only distant relatives, that’s a challenge."
He added: “A big thing to underline is there have been vast improvements in what people have been able to do with ancient DNA because of improvements to instrumentation and software.”