Why Giant Ground Sloths Evolved Similarly Three Times

Speedy Summary

• Research reveals that three different groups of sloths independently evolved to gigantic sizes, primarily influenced by cold adn dry climatic conditions.
• Ancient sloths displayed a wide range of sizes, with some ground-dwelling species reaching up to 5 tonnes.
• Sloth body size evolution was heavily tied to environmental shifts like the cooling climate and Andean mountain growth in South America.
• Transitioning to tree habitats caused certain sloth groups to decrease in size,resembling modern sloths.
• Giant ground-dwelling sloths faced extinction during periods coinciding with human expansion across the Americas (~12,000 years ago) and the caribbean (~6000 years ago). Tree-dwelling species survived due to being harder for humans to hunt.
• The study utilized data spanning 35 million years from 67 extinct and existing sloth genera, examining physical features, DNA/proteins, habitat trends, diet, lifestyle changes, and body mass estimates.

Image Caption: Ancient sloths came in varied sizes (Credit: Diego Barletta).