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Glyptodonts are an extinct
Glyptodonts possessed a tortoise-like body armour, made of bony deposits in their skin called osteoderms or scutes. Each species of glyptodont had a unique osteoderm pattern and shell type. With this protection, they were armored 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 Sedan (automobile), automobiles. The presence of such heavy defenses suggests they were prey of a large, effective predator. At the time that glyptodonts evolved, the apex predators in the island continent of South America were Phorusrhacidae, phorusrhacids, a family of giant flightless carnivorous birds.
In physical appearance, glyptodonts superficially resembled the much earlier dinosaurian Ankylosauridae, ankylosaurs and, to a lesser degree, the recently extinct giant Meiolaniidae, 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.
Glyptodonts were grazing herbivores. Like many other xenarthrans, they had no incisor or canine (tooth), 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 muscles.
A History of Life in 10 Fossils
, ''Smithsonian Magazine,'' 15 October 2014
Glyptodont article at ScienceBlogs
with photos * {{Taxonbar, from1=Q23015579, from2=Q132641 Cingulates Prehistoric cingulates Pleistocene xenarthrans, Pliocene xenarthrans, Miocene xenarthrans, Oligocene xenarthrans, Eocene xenarthrans, Lutetian first appearances Holocene extinctions Neogene mammals of South America Pleistocene mammals of South America Pleistocene mammals of North America Taxa named by Hermann Burmeister
subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
of large, heavily armoured armadillo
Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...
s. They arose in South America around 48 million years ago and spread to southern North America after the continents became connected several million years ago. The best-known genus within the group is '' Glyptodon''.
While they were formerly considered to constitute the distinct family Glyptodontidae, in 2016, an analysis of '' Doedicurus'' Mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
(also known as mtDNA / mDNA) found that it was, in fact, nested within the modern armadillos as the sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and t ...
of a clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
consisting of Chlamyphorinae
Chlamyphorinae is a subfamily of South American armadillos in the family Chlamyphoridae. Members of this subfamily, the fairy armadillos, are largely fossorial and have reduced eyes and robust forearms with large claws for digging.
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Ta ...
and Tolypeutinae
Tolypeutinae is a subfamily of armadillos in the family Chlamyphoridae, consisting of the giant, three-banded and naked-tailed armadillos.
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Taxonomy
It contains the following genera:
*''Cabassous''
*''Kuntinaru''
*''Priodontes''
*''To ...
. For this reason, glyptodonts and all armadillos but ''Dasypus
''Dasypus'' is the only extant genus in the family Dasypodidae. Its species are known as long-nosed or naked-tailed armadillos. They are found in South, Central, and North America, as well as on the Caribbean islands of Grenada, Trinidad and Toba ...
'' were relocated to a new family, Chlamyphoridae, and glyptodonts were demoted from the former family Glyptodontidae to a subfamily.
Evolution
Glyptodonts first evolved during the Eocene in South America, which remained their center of species diversity. For example, an Early Miocene glyptodont with many primitive features, when compared to other species, '' Parapropalaehoplophorus septentrionalis,'' was discovered at a now-elevated site in Chile and described in 2007. After theIsthmus of Panama
The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country ...
formed about three million years ago, the genus ''Glyptotherium
''Glyptotherium'' (from Greek for 'grooved or carved beast') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Early Pliocene, about 4.9 million years ago, to the Early Holocene, around 7,000 years ...
'' spread north as part of the Great American Interchange
The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which lan ...
, as did pampatheres, armadillo
Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...
s and a number of other types of xenarthrans (e.g., ground sloths).
Description
Glyptodonts possessed a tortoise-like body armour, made of bony deposits in their skin called osteoderms or scutes. Each species of glyptodont had a unique osteoderm pattern and shell type. With this protection, they were armored 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 Sedan (automobile), automobiles. The presence of such heavy defenses suggests they were prey of a large, effective predator. At the time that glyptodonts evolved, the apex predators in the island continent of South America were Phorusrhacidae, phorusrhacids, a family of giant flightless carnivorous birds.
In physical appearance, glyptodonts superficially resembled the much earlier dinosaurian Ankylosauridae, ankylosaurs and, to a lesser degree, the recently extinct giant Meiolaniidae, 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.
Behaviour
Glyptodonts were grazing herbivores. Like many other xenarthrans, they had no incisor or canine (tooth), 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 muscles.
Extinction
Glyptodonts became extinct at the end of the Last Glacial Period, last ice age along with a large number of other megafaunal species, including Pampatheriidae, pampatheres, the giant ground sloths, and ''Macrauchenia''. Their much smaller, more lightly armored and flexiblearmadillo
Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...
relatives survived. The extinction of the glyptodonts coincided with Settlement of the Americas, the arrival of early humans in the Americas. Archeological evidence suggests that these humans made use of the animals' armored shells.Smithsonianmag.com,A History of Life in 10 Fossils
, ''Smithsonian Magazine,'' 15 October 2014
References
External links
Glyptodont article at ScienceBlogs
with photos * {{Taxonbar, from1=Q23015579, from2=Q132641 Cingulates Prehistoric cingulates Pleistocene xenarthrans, Pliocene xenarthrans, Miocene xenarthrans, Oligocene xenarthrans, Eocene xenarthrans, Lutetian first appearances Holocene extinctions Neogene mammals of South America Pleistocene mammals of South America Pleistocene mammals of North America Taxa named by Hermann Burmeister