|This illustration shows two male glyptodonts (Doedicurus clavicaudatus) facing off: Scientists believe that the massive, club-shaped tails were probably used more for intraspecific combat than defense against predators. Credit: Peter Schouten|
New genetic research reveals that modern-day armadillos are closely related to glyptodonts -- huge, armored mammals with a spiked clubbed tail that went extinct in the Americas at the end of the last ice age.
Although scientists like Charles Darwin collected partial remains of glyptodonts in the early 19th century, at first nobody knew what kind of mammal they represented. It was eventually accepted that glyptodonts must be related in some way to armadillos, the only other New World mammals to develop a protective bony shell.
However, because of the many physical differences between these two groups, most paleontologists have held the view that they must have separated very early in their evolutionary history. The recent findings, published in the journal Current Biology, contradict that long-held belief and confirm that glyptodonts likely originated less than 35 million years ago from ancestors within lineages leading directly to the modern armadillo family Chlamyphoridae.
More surprising still, the researchers discovered that the closest relatives of glyptodonts -- some species of which may have weighed two tons or more -- include not only the giant armadillo (Priodontes maximus), which can weigh up to 25 pounds, but also the four-ounce pink fairy armadillo, or pichiciego (Chlamyphorus truncatus).
|The fossil of this glyptodont is on display in the American Museum of Natural History's Hall of Primitive Mammals. Credit: AMNH/ D. Finnin|