page_title: Glyptodon
section_title: Osteoderms
hierarchical_section_title: Glyptodon / Anatomy / Osteoderms
caption_attribution_description: Glyptodon asper
context_page_description: Glyptodon was a genus of large, heavily armored mammals of the subfamily Glyptodontinae – relatives of armadillos – that lived during the Pleistocene epoch. It was roughly the same size and weight as a Volkswagen Beetle, though flatter in shape. With its rounded, bony shell and squat limbs, it superficially resembled a turtle, and the much earlier dinosaurian ankylosaur – providing an example of the convergent evolution of unrelated lineages into similar forms. In 2016 an analysis of Doedicurus mtDNA found it was, in fact, nested within the modern armadillos as the sister group of a clade consisting of Chlamyphorinae and Tolypeutinae. For this reason, glyptodonts and all armadillos but Dasypus were relocated to a new family, Chlamyphoridae, and glyptodonts were demoted from the former family Glyptodontidae to a subfamily.
context_section_description: Before the Pleistocene, Glyptodon’s osteoderms were attached by syntoses and were found in double or triple rows on the front and sides of the carapace's edges, as well as in the tail armor and cephalic shield. The carapace's osteoderms were conical with a rounded point, while the ones on the tail were just conical. The sulci between these raised structures were deep and wide with parallel lines.
  In the early 2000s, the presence of osteoderms on Glyptodon’s face, hind legs, and underside was confirmed in several species. The fossils with these characteristics were from the Pleistocene. These small to medium-sized ossicles were actually embedded in the dermis and did not connect in a pattern.
  The appearance of this new trait coincides with the arrival of North American predators in South America as part of the Great American Interchange, after the two continents became connected about three million years ago. For this reason, some scientists hypothesize that the osteoderms developed as a defensive/offensive mechanism. This belief is furthered by the discovery of fractured dorsal armor, which implies that Glyptodon had been in physical conflict with other species.
caption: Close-up view of carapace
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