Study uncovers genomic data linking extinct giant ground sloth to modern species

Mohammed El-Said
3 Min Read

Benefiting from the remains of an ancient giant ground sloth, or Mylodon darwinii, researchers have uncovered important genomic data. The emblematic creature was named after Charles Darwin, whose discovery of fossilised remains in South America is considered to be one of his significant scientific achievements, according to a new study published in the Proceedings of the Royal Society B.

Using a bone fragment which dates back nearly 13,000 years, scientists teased out and reconstructed DNA fragments to obtain a high-quality mitochondrial genome and nuclear genomic information. According to the study, the analysis proves for the first time that the giant ground sloth—which went extinct approximately 10,000 years ago—is a close relative of the modern two-fingered sloth, which is believed to be one of the world’s slowest mammals.

The study suggested that the two species diverged from one another approximately 22m years ago. The much smaller modern sloth evolved over time to inhabit trees, where they spend virtually their entire life suspended upside down.

“Our study confirms the convergent evolution of the two, tree dwelling modern sloths from two distinct lineages of extinct giant ground sloths,” said Hendrik Poinar, lead author of the study and director of McMaster University’s Ancient DNA Centre and principal investigator at the Michael G DeGroote Institute for Infectious Disease Research. “This means tree-living evolved independently, twice, which is remarkable.”

The scientists said the sample was exceptionally well-preserved. It was taken from the famous Mylodon Cave in Chile, which derives its name from the numerous remains of ground sloths found inside. The constant cold and dry conditions of the cave have preserved a scientific treasure trove including bones, claws, faeces, and even large pieces of mummified skin still covered with blond fur.

“The incredible conservation of the bone sample we used in this study offers promising prospects for sequencing the full genome of this extinct species because of the high percentage of DNA that it contains,” said Frédéric Delsuc, co-author of the paper and director of research at the Centre National de Recherche in France, adding, “this will certainly generate more insights and information into their unique features and ultimate extinction,” he added.

These remains that were found at the exceptional site of Mylodon Cave, in Patagonia, Chile, were the first non-human samples used by scientists in early genetic tests, which yielded genuine ancient DNA. Advances in sequencing technology have led to a deeper understanding of ancient and extinct species, including the Columbian and woolly mammoths, giant lemurs, and steppe bison.

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Mohammed El-Said is the Science Editor for the Daily News Egypt with over 8 years of experience as a journalist. His work appeared in the Science Magazine, Nature Middle East, Scientific American Arabic Edition, SciDev and other regional and international media outlets. El-Said graduated with a bachelor's degree and MSc in Human Geography, and he is a PhD candidate in Human Geography at Cairo University. He also had a diploma in media translation from the American University in Cairo.
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