{"id":262665,"date":"2025-05-29T13:55:44","date_gmt":"2025-05-29T13:55:44","guid":{"rendered":"https:\/\/peraltafinancing.com\/aerospace\/giant-sloths-the-size-of-elephants-once-walked-along-the-ground-heres-how-the-massive-animals-evolved-and-declined\/"},"modified":"2025-05-29T13:55:44","modified_gmt":"2025-05-29T13:55:44","slug":"giant-sloths-the-size-of-elephants-once-walked-along-the-ground-heres-how-the-massive-animals-evolved-and-declined","status":"publish","type":"post","link":"https:\/\/fivemor.com\/?p=262665","title":{"rendered":"Giant Sloths the Size of Elephants Once Walked Along the Ground. Here’s How the Massive Animals Evolved and Declined"},"content":{"rendered":"


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Researchers analyzed fossils and DNA to get a big-picture view of sloth evolution and determine what drove their immense size variation<\/h2>\n
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Margherita Bassi<\/a><\/p>\n

– Daily Correspondent<\/span><\/p>\n

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Researchers revealed that differences in sloth habitats drove the wide variation in size seen in extinct species.
\n Diego Barletta<\/span>
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Today, sloths<\/a> are slow-moving, tree-dwelling creatures that live in Central and South America and can grow up to 2.5 feet long<\/a>. Thousands of years ago, however, some sloths walked along the ground, weighed around 8,000 pounds and were as big as Asian elephants<\/a>. Some of these now-extinct species were \u201clike grizzly bears, but five times larger,\u201d as Rachel Narducci<\/a>, collection manager of vertebrate paleontology at the Florida Museum of Natural History, says in a statement<\/a>.<\/p>\n

In a study published last week in the journal Science<\/em><\/a><\/em>, Narducci and her colleagues studied ancient and modern sloth DNA along with more than 400 sloth fossils to shed light on the shocking differences in their ancient sizes\u2014from the elephant-sized Megatherium<\/a><\/em> ground sloth to its 14-pound relatives living in trees. While it\u2019s clear that tree-dwelling lifestyles necessitate small bodies, scientists weren\u2019t sure why ground sloths specifically demonstrated such vast size diversity.<\/p>\n

To investigate this, the team used their genetic and fossil analyses to reconstruct a sloth tree of life that reaches back to the animals\u2019 emergence more than 35 million years ago. They integrated data on sloths\u2019 habitats, diets and mobility that had been gathered in previous research. With a computer model, they processed this information, which ultimately indicated that sloths\u2019 size diversity was mostly driven by their habitats and climates.<\/p>\n

\u201cWhen we look at what comes out in the literature, a lot of it is description of individual finds, or new taxa,\u201d Greg McDonald<\/a>, a retired regional paleontologist with the U.S. Bureau of Land Management who was not involved with the study, tells Science News<\/em><\/a>\u2019 Carolyn Gramling. The new work is \u201cmore holistic in terms of looking at a long-term pattern. Often, we don\u2019t get a chance to step back and get the big picture of what\u2019s going on.\u201d<\/p>\n

The big picture suggests that since the emergence of the oldest known sloths\u2014ground animals around the size of a Great Dane\u2014the creatures evolved into and out of tree living a number of times. Around 14 million to 16 million years ago, however, a time of global warming called the Mid-Miocene Climatic Optimum<\/a> pushed sloths to become smaller, which is a known way for animals to respond to heat stress<\/a>.<\/p>\n

Warmer temperatures might have also seen more rain, which would have created more forest habitats ideal for tree-dwelling sloths. Around a million years later, however, ground sloths grew bigger as the planet\u2019s temperature cooled. \u201cGigantism is more closely associated with cold and dry climates,\u201d Daniel Casali<\/a>, a co-author of the paper and a researcher of mammalian evolution at the University of S\u00e3o Paulo, tells New Scientist<\/em><\/a>\u2019s Jake Buehler.<\/p>\n

A larger body mass would have helped the animals traverse environments with few resources more efficiently, Narducci says in the statement. In fact, these large ground sloths spread out across diverse habitats and thrived in different regions. The aquatic sloth Thalassocnus<\/em><\/a> even evolved marine adaptations similar to manatees.<\/p>\n

Ground sloths achieved their greatest size during the last ice age\u2014right before starting to disappear around 15,000 years ago. Given that humans arrived in North America around the same time (though recent research indicates they may have arrived as far back as 20,000 years ago<\/a>), some scientists say humans are the obvious cause of the sloths\u2019 demise. While tree-dwelling sloths were out of reach to our ancestors, the large and slow ground animals would have made easy targets. Even still, two species of tree sloths in the Caribbean disappeared around 4,500 years ago\u2014also shortly after humans first arrived in the region, according to the statement.<\/p>\n

While the study joins a host of research indicating that humans drove various large Ice Age animals to extinction, \u201cin science, we need several lines of evidence to reinforce our hypotheses, especially in unresolved and highly debated issues such as the extinction of megafauna,\u201d says Tha\u00eds Rabito Pansani<\/a>, a paleontologist from the University of New Mexico who did not participate in the study, to New Scientist<\/em>.<\/p>\n

The International Union for Conservation of Nature currently recognizes seven <\/strong>sloth species<\/a>\u2014following a recent species discovery<\/a>\u2014and three<\/a> are<\/a> endangered<\/a>. As such, \u201cone take-home message is that we need to act now to avoid a total extinction of the group,\u201d says lead author Alberto Boscaini<\/a>, a vertebrate paleontologist from the University of Buenos Aires, to the BBC<\/a>\u2019s Helen Briggs.<\/p>\n

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