GLYPTODONTS

In my immediately preceding blog post, I discussed ground sloths, which represent an extinct xenarthran (“zee-nar-thrans”) group. In this present post I discuss another extinct xenarthran group, namely, the glyptodonts. 

Both ground sloths and glyptodonts originated in South America and migrated to North America.

Extant (still living) xenarthrans are tree sloths, anteaters, and armadillos. Interestingly, armadillos are the direct ancestors of glyptodonts (this fact is based on extracted DNA from an extinct glyptodont). 

Glyptodonts were large (up to car size = several tons in weight) and heavily armored. Their heavy shells were made of bony plates. Glyptodonts are named for their distinctive teeth, which were used for grazing. Additionally, glyptodonts also had large blunt hoof-like claws.

One of the most common glyptodonts is Glyptodon, which was about 9 feet (2.7 m) long. This glyptodont migrated to North America during Pleistocene time.

A plastic model of Glypyodon.

The skull of Glyptodont is nearly circular in shape, as shown in the following  image:

The largest glyptodont of all time was Doedicurus clavicaudatus, the only species of this particular genus. This strictly South American glyptodont species might have been the last surviving glyptodont. It is of Pleistocene age (8,000 to 7,000 years before present) and lived in Patagonia, South America. It weighed about 3,000 pounds, was about 13 feet long and 4 feet high, and had a spiked tail that weighed 88 to 143 pounds. This spiked tale was probably used for defense by means swinging it from side to side, thereby delivering bone-crushing blows to predators.

Doedicurus clavicaudatus.

As shown in my following diagram, glyptodonts arose in South America about 20 million years ago. They spread to southern part of North America after the continents became connected about 3 million years ago. They lived long after the disappearance of mammoths and saber-tooted casts, but the reason why glyptodonts went extinct is not known, (could it have been extinction by humans?).

Literature search and drafting by R.L. Squires, Fall, 2022.

All of the sketches of glyptodont shown above are based on figures in Fenton and Fenton, 1989, The Fossil Book, revised edition, Doubleday, New York.