Sunday, 14 March 2021

ANCIENT ARMADILLOS

Glyptodonts are the early ancestors of our modern armadillos that roamed North and South America during the Pleistocene. Armadillos have ranged in size from the size of an armoured car to the size of a small, family dog. It's quite a range and the more you move forward in time, the smaller they've become.

Glyptodonts became extinct at the end of the last ice age. They, along with a large number of other megafaunal species, including pampatheres, the giant ground sloths, and the Macrauchenia, left this Earth but their bones tell a story of brief and awesome supremacy.

Today, Glyptodonts live on through their much smaller, more lightly armoured and flexible armadillo relatives. They defended themselves against Sabre Tooth Cats and other predators but could not withstand the arrival of early humans in the Americas. Archaeological evidence suggests that these humans made use of the animal's armoured shells and enjoyed the meat therein. Glyptodonts possessed a tortoise-like body armour, made of bony deposits in their skin called osteoderms or scutes. Beneath that hard outer coating was a food source that our ancestors sought for their survival.

Each species of glyptodont had a unique osteoderm pattern and shell type. With this protection, they were armoured like turtles; glyptodonts could not withdraw their heads, but their armoured skin formed a bony cap on the top of their skull. Glyptodont tails had a ring of bones for protection. Doedicurus possessed a large mace-like spiked tail that it would have used to defend itself against predators and, possibly, other Doedicurus. Glyptodonts had the advantage of large size.

Many, such as the type genus, Glyptodon, were the size of modern automobiles. The presence of such heavy defences suggests they were the prey of a large, effective predator. At the time that glyptodonts evolved, the apex predators in the island continent of South America were phorusrhacids, a family of giant flightless carnivorous birds.

The ancient Armadillo Glyptodon asper
In physical appearance, glyptodonts superficially resembled the much earlier dinosaurian ankylosaurs and, to a lesser degree, the recently extinct giant meiolaniid turtles of Australia.

These are examples of the convergent evolution of unrelated lineages into similar forms. The largest glyptodonts could weigh up to 2,000 kilograms. Like most of the megafauna in the Americas, they all became extinct at the end of the last ice age 10,000 years ago. The deeper you get in time, the larger they were. Twenty thousand years ago, they could have ambled up beside you in what would become Argentina and outweighed a small car.

A few years back, some farmers found some interesting remains in a dried-out riverbed near Buenos Aires. The find generated a ton of palaeontological excitement. Fieldwork revealed this site to contain two adults and two younger specimens of an ancient armadillo. These car-size beasties would have been living and defending themselves against predators like Sabre Tooth Cats and other large predators of the time by employing their spiked club-like tails and thick bony armour.

Glyptodonts were unlikely warriors. They were grazing herbivores. Like many other xenarthrans, they had no incisor or canine teeth but had a number of cheek teeth that would have been able to grind up tough vegetation, such as grasses. They also had distinctively deep jaws, with large downward bony projections that would have anchored their powerful chewing muscle.

Image Two: By Arentderivative work: WolfmanSF (talk) -  http://de.wikipedia.org/wiki/Bild:Glyptodon-1.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=665483