Ancient armadillos go clubbing in South America

时间:2019-03-08 07:16:04166网络整理admin

By Myles McLeod TWO-TONNE armadillos known as glyptodonts probably spent prehistory bashing each other with their club-like tails. Fractures in the carapaces of some fossil specimens suggested brutal sparring, and a team in Leeds has now confirmed that a good swat from the tail could have inflicted such an injury. South American glyptodonts, relatives of armadillos, became extinct about 10 000 years ago. Their protective armour weighed up to 400 kilograms, about the weight of five men, and it probably served as a tortoise-like hideaway from giant carnivorous birds and sabre-toothed mammals. However, research by McNeill Alexander at the University of Leeds and his colleagues suggests that the formidable carapace was also used as a shield in fights between glyptodonts—and that tails were powerful weapons. Glyptodonts had broad, muscular tails protected by tough plates. In some species, these fused into mace-like clubs at the tip. Like deer antlers, they were probably used not against predators but rather to fight each other, perhaps over mates or territory. “It suggests that glyptodont design has a lot to do with sex and violence,” says Alexander. His team performed biomechanical tests to see if the tail was up to the task of seriously damaging an opponent. Drawing from previous work on smashing human and goat skulls, and after scaling up the forces, Alexander calculated that the tail would need between 1400 and 6000 joules to crack the carapace. Then, using a cast of a fossil tail cone, the team estimated the muscle mass controlling each side of the tail and how much energy would be needed to move it in a rapid tail snap—about 3000 joules. So the tail could have done the damage. Luckily for the glyptodonts,