Glyptodon

Glyptodon (Greek for "grooved or carved tooth") was a large, armored mammal of the family Glyptodontidae, a relative of armadillos that lived during the Pleistocene epoch. With its rounded, bony shell and squat limbs, it superficially resembled turtles, and the much earlier dinosaurian ankylosaur, as an example of the convergent evolution of unrelated lineages into similar forms.

Discovery

Although Darwin is said to have found the first glyptodonts (the family), the first mention of the genus Glyptodon in Europe was in 1823, from the first edition of Cuvier's "Ossemens Fossiles."[3] The then unnamed Glyptodon was briefly mentioned in a letter from Don Damsio Laranaga. He had found "a femur... It was about seven pounds, and maybe six or eight inches wide", as well as part of a tail.[3] At the time, the discovery was believed to have belonged to Megatherium, a type of giant ground sloth. A man named Sellow found some carapace plates in three-foot deep clay in Uruguay four years later. That discovery only made the professors even more certain that the discoveries were of the Megatherium, since the bones of this prehistoric giant sloth were usually found in similar conditions and Cuvier had said that the genus was loricated.[3]

Although some believed that the armor resembled that of the modern armadillo, the popular opinion was the Megatherium theory. It was not until Professor E. D’Alton wrote a memoir to the Berlin Academy in 1833 comparing the extreme similarities of these mysterious fossils to that of the armadillo, that the scientific world seriously considered that the pieces of carapaces and fragments of bone could belong to some prehistoric version of Dasypus. D’Alton said that “all the peculiarities of the former [Dasypus] may be paralleled to the latter [fossil pieces]”[3] He concluded that the fossils belonged to some prehistoric version of an armadillo. However, since a full skeleton was not available at the time, he said that his idea was not conclusive. This uncertainty in the fossil remains continued until a man named Dr. Lund identified the remains as a new genus in his 1837 memoir.

Naming of Glyptodon

When scholars first acknowledged the genus Glyptodon, there was not a consensus on its name. In 1837 Dr. Lund, a professor who wrote a memoir on Brazil’s ancient fauna, suggested these creatures be recognized as the new genus “Hoplophorus”. In 1838, another scientist, Professor Bronn, published in the second edition of his book Lethaea Geognostica a proposal for the new genus to be called “Chlamydotherium”. In Professor D’Alton’s 1839 memoir, it was called “Pachypus”. The director at the Museum of Natural History in Dijon at the time, M.L. Nodot, had named the genus “Schistopleuron”.[4]

It was finally given a single name when English scholar Richard Owen noticed the similarities of the genera his colleagues were describing in their publications. Owen realized they were all the same genus from their depictions, from carapace to tooth structure. He decided on “Glyptodon”, which means "grooved or carved tooth". The name was originally coined by Sir Woodbine Parish, the man who had sent some Glyptodon fossils to Europe. Those fragments of carapace and bones he sent had been heavily studied at the time and had assisted in the recognition of the new genus.[4]

After unifying the name of this genus, Owen continued working on its taxonomy. In 1845, after analyzing the fossils of his colleagues, he named four species within the genus: G. clavipes, G. reticulatus, G. ornatus, and G. tuberculatus.

Evolution

Glyptodon is part of the superorder of placental mammals known as Xenarthra. This clade of mammals also includes anteaters, tree sloths, armadillos, and extinct ground sloths and pampatheres.