Extinct glyptodonts really were gigantic armadillos, ancient DNA shows

February 22, 2016
An illustrated rendition of two glyptodonts. Credit: Peter Schouten

If you could travel back in time to South America thousands of years ago, you might have caught a glimpse of an animal known as a glyptodont living alongside giant ground sloths and saber-toothed cats. Glyptodonts looked like gigantic and fearsome armadillos; one of the largest species, Doedicurus, weighed as much as a ton and had a powerful club-shaped and spiky tail.

There's a good reason for the resemblance to armadillos, according to researchers who have reconstructed the family tree of these ancient beasts based on their mitochondrial genome, reconstructed from small fragments of DNA extracted from bits of a protective, bony carapace. The molecular evidence reported in the Cell Press journal Current Biology on February 22 confirms that gigantic armadillos are exactly what glyptodonts were.

"Glyptodonts in fact represent an extinct lineage that likely originated about 35 million years ago within the armadillo radiation," says Hendrik Poinar of McMaster University in Canada.

"Glyptodonts should probably be considered a subfamily of gigantic armadillos," adds Frédéric Delsuc of CNRS in France. "We speculate that the peculiar structure of their unarticulated carapace might have evolved as a response to the functional constraint imposed by the size increase they experienced over time."

Poinar and Delsuc have had a long interest in living and extinct xenarthrans (a group including armadillos, anteaters, and sloths) and in their evolutionary relationships to each other. Recent advances in DNA capture and genome sequencing technology are now making it possible to fish DNA fragments out of fossil remains to help put those evolutionary family trees together.

An illustration of a glyptodont. Credit: Artist Carl Buell

In the new study, the researchers used a technical trick allowing them to specifically fish Doedicurus mitochondrial DNA out of an extract containing plenty of DNA from other sources. They used RNA baits designed from computationally reconstructed ancestral DNA sequences based on known modern sequences of glyptodonts' living relatives.

Their phylogenetic analysis establishes that glyptodonts are in fact deeply nested within the armadillo crown group, representing a distinct subfamily (Glyptodontinae) within the family known as the Chlamyphoridae, represented today by the dwarf pink fairy armadillo and the , for instance. Molecular dating suggests that glyptodonts diverged no earlier than about 35 million years ago, the researchers report, in good agreement with their known fossil record.

Melanie Kuch, research assistant, Department of Anthropology at McMaster University examines ancient glyptodont specimens. Credit: McMaster University

Their findings also highlight the impressive increase in glyptodonts' size over evolutionary time. The researchers estimate that the last common ancestor of glyptodonts and their living armadillo relatives weighed in at a mere 6 kilograms, suggesting a "spectacular increase in glyptodont body mass." That's consistent with the , which shows glyptodonts evolved from medium-sized forms (about 80 kilograms) to become true megafauna in the Pleistocene (reaching 2,000 kilograms) before their disappearance at the end of the last ice age.

The fossil of this glyptodont is on display in the Museum's Hall of Primitive Mammals. Credit: © AMNH/ D. Finnin

Poinar and Delsuc say they'll continue to explore ancient DNA lifted from numerous other fossil xenarthrans, including .

Explore further: 'Pre-historic' animal shell found in Argentina

More information: Current Biology, Delsuc et al.: "The phylogenetic affinities of the extinct glyptodonts" dx.doi.org/10.1016/j.cub.2016.01.039

Related Stories

'Pre-historic' animal shell found in Argentina

December 29, 2015

A passer-by on Christmas Day found a meter-long shell on a riverbank in Argentina which may be from a glyptodont, a prehistoric kind of giant armadillo, experts said Tuesday.

Extinct Mammal Used its 'Sweet Spot' to Club Rivals

August 27, 2009

(PhysOrg.com) -- Scientists in Uruguay studying extinct mammals called glyptodonts have discovered they used a "sweet spot" in their tails, just like baseball players use the center of percussion (CP), or sweet spot, in their ...

Rooting the family tree of placental mammals

February 15, 2016

Placental mammals consist of three main groups that diverged rapidly, evolving in wildly different directions: Afrotheria (for example, elephants and tenrecs), Xenarthra (such as armadillos and sloths) and Boreoeutheria (all ...

Sloths are no slouches when it comes to evolution

September 10, 2014

Today's sloths might be known as slow, small animals, but their ancestors developed large body sizes at an amazing rate, according to an evolutionary reconstruction published today in the open access journal BMC Evolutionary ...

Recommended for you

Important ancient papyrus seized from looters in Israel

October 27, 2016

(Phys.org)—Eitan Klein, a representative of the Israel Antiquities Authority, has announced that an important papyrus document dated to 2,700 years ago has been seized from a group of Palestinian looters who reportedly ...

Ancient parrot fossil found in Siberia

October 26, 2016

(Phys.org)—A Russian paleontologist has discovered a parrot fossil uncovered in Siberia several years ago—the first evidence of parrots living in Asia. In his paper published in Biology Letters, Nikita Zelenkov describes ...

Ancient burials suggestive of blood feuds

October 24, 2016

There is significant variation in how different cultures over time have dealt with the dead. Yet, at a very basic level, funerals in the Sonoran Desert thousands of years ago were similar to what they are today. Bodies of ...


Adjust slider to filter visible comments by rank

Display comments: newest first

5 / 5 (3) Feb 22, 2016
So it should be that much easier to reverse engineer them. And bring them back.
5 / 5 (2) Feb 22, 2016
Wonder what Leprosy was doing back then, as Armadillos are a vector.
Captain Stumpy
5 / 5 (3) Feb 22, 2016
i can't even see the word Armadillo without thinking of Zefrank and his video: https://www.youtu...iUX1Ursk

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.