Glyptodonts Clubbed Their Foes (and each other)

Glyptodonts were unlike any living species of mammal.  A carapace, attached to their hips, covered all of their body except for the head.  This protected them from most predators, though evidence from 1 specimen suggests a frontal attack by a big cat could prove fatal (See:  Their shell provided a wonderful defense, but glyptodonts were capable of taking the offensive.  When confronted by a predator, a glyptodont turned its back and swung its tail with devastating force.  Paleontologists have determined these tail blows were powerful enough to damage the carapace of other glyptodonts.  They also hypothesize of the existence of a fatty pad behind the shoulder that helped withstand these intraspecific blows.  Male glyptodonts fighting over mates turned their backs to each other and swung their tails, battering each other’s carapace.  Occasionally, these blows caused carapaces to fracture.  There is 1 specimen in a South American museum that shows evidence of such an injury, though the wound healed and this individual glyptodont survived.  Some species of glyptodonts had clubs or spikes on their tails.  They were located where the center of percussion would be.  The center of percussion is the equivalent of the “sweet spot” on a baseball bat or tennis racquet.

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Glyptodonts used their tails as defensive weapons and in intraspecific conflicts over mates.  Scientists determined the club on this species was at the center of percussion or sweet spot, just like a baseball batter’s sweet spot.

Glyptodon Shell

A glyptodont shell mounted in a South American museum.  A glyptodont mounted in another musuem shows a fracture from being hit by another glyptodont’s tail club.  That carapace healed.

Here’s an artist’s rendition of glyptodonts battling over a mate.

Glyptodonts belonged to the edentate order (some scientists prefer to call it the xenartha order), a classification that includes armadilloes, anteaters, and sloths.  The edentates originally evolved in South America, but some species spread to North America when a landbridge between the continents emerged millions of years ago.  There were 5 genera of glyptodonts living in South America during the Pleistocene, but only 1 species occurred in southeastern North America during the late Pleistocene.  The North American species lived in Florida and the southeastern coastal plain during warm climate phases.  The largest species of glyptodont lived in South America.  This member of the Doedicurus genus reached 4000 pounds.  Glyptodonts were a successful lineage of mammals that lived for tens of millions of years but became extinct about the same time man appears in the archaeological record.  I have no doubt their otherwise well adapted defenses were useless against hunting humans.  A man could simply run forward and hit a glyptodont over the head while avoiding the tail blows.  The fatty deposit behind a glyptodont’s shoulder would have been a delicacy.

Ankylosaurs and glyptodonts are a good example of convergent evolution.  Ankylosaurs, a dinosaur that became extinct 65 million years ago, also had carapaces and swung their tails in self defense in battles over mates.


Ankylosaurs had a similar adaptation as glyptodonts–an example of convergent evolution.


Alexander, R.

“Tail Blow Energy and Carapace Fractures in Large Glyptodont (Mammalia: Xenartha)”

Zoological Journal of the Linnean Society  126 1999

Blanco, Ernesto; Washington jones, and Andres Ringle Knecht

“The Sweet Spot of a Biological Hammer: The Centre of Percussion of a Glyptodont (Mammalia: Xenartha)”

Proceedings of the Royal Society of Biological Science 276 (1675) 2009



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