Armadillo walking besides road

If you have never been up close to an armadillo, it is hard to describe how strange and freak looking they really are.  Back when giant ground sloths and saber-toothed cats occupied South America, car-sized armadillos known as glyptodont were strutting around between 56 and 34 million years ago.

Glyptodont weighed as much as a ton and had a clubbed, spiky tale.  From fossil evidence, we can deduce that they had tortoise-like body armor with layered deposits of bone within their skin and a bony cap on top of their skull.  


A new study by researchers at McMaster University in Canada and the National Center for Scientific Research in France sought to definitively state how these animals evolved and what exactly they are related to.  They started with the DNA of one of the largest glyptodonts, the Deodicurrus.  The Deodicurrus weighed around 1.5 tons and was one of the last of its family to become extinct at the end of the last ice age 12,000 years ago.

By comparing the DNA to current DNA of living Xenartha they were able to conclude that it wasn’t just a relative of the armadillo, it actually belongs in the evolutionary group, making it an ancient, giant armadillo.

They were also able to date when the family first appeared. “Glyptodonts in fact represent an extinct lineage that likely originated about 35 million years ago within the armadillo radiation,” said Hendrik Poinar, a professor of physical anthropology at McMaster University in Canada and co-author of the study, in a statement.

This date coincides with the best fossil evidence a Glyptatelus that was estimated at 36-38 million years of age.

The study also shows how drastic the size of the glyptodonts changed over time.  With the last common ancestor weighing around 13-14 pounds, some of the last surviving ancestors weight 2 tons, about the size of a rhinoceros.

These herbivores are relatives with the anteaters, tree sloths and of course armadillos.