Glyptodonts are an extinct
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
''Glyptodon'' (from Greek for 'grooved or carved tooth': γλυπτός 'sculptured' and ὀδοντ-, ὀδούς 'tooth') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Pleistocene, around 2.5 ...
''.
While they were formerly considered to constitute the distinct family Glyptodontidae, in 2016, an analysis of ''
Doedicurus
''Doedicurus'', or ''Dædicurus'', is an extinct genus of glyptodont from South America containing one species, ''D. clavicaudatus''. Glyptodonts are a member of the family Chlamyphoridae, which also includes some modern armadillo species, ...
''
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 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'' were relocated to a new family,
Chlamyphoridae
Chlamyphoridae is a family of cingulate mammals. While glyptodonts have traditionally been considered stem-group cingulates outside the group that contains modern armadillos, there had been speculation that the extant family Dasypodidae could b ...
, and glyptodonts were demoted from the former family Glyptodontidae to a subfamily.
Evolution
Glyptodonts first evolved during the
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
in
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
, which remained their center of
species diversity
Species diversity is the number of different species that are represented in a given community (a dataset). The effective number of species refers to the number of equally abundant species needed to obtain the same mean proportional species abundan ...
. 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
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
and described in 2007. After the
Isthmus of Panama formed about three million years ago, the genus ''
Glyptotherium'' 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
pampathere
Pampatheriidae ("Pampas beasts") is an extinct family of large plantigrade armored armadillos related to extant armadillos in the order Cingulata. However, pampatheriids have existed as a separate lineage since at least the middle Eocene Mus ...
s,
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
![Doedicurus and Glyptodon](https://upload.wikimedia.org/wikipedia/commons/b/b2/Doedicurus_and_Glyptodon.jpg)
Glyptodonts possessed a
tortoise
Tortoises () are reptiles of the family Testudinidae of the order Testudines (Latin: ''tortoise''). Like other turtles, tortoises have a turtle shell, shell to protect from predation and other threats. The shell in tortoises is generally hard, ...
-like body armour, made of bony deposits in their skin called
osteoderm
Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinc ...
s or
scute
A scute or scutum (Latin: ''scutum''; plural: ''scuta'' "shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of birds. The term is also used to describe the anterior po ...
s. Each species of glyptodont had a unique osteoderm pattern and shell type. With this protection, they were armored like
turtle
Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...
s; 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
''Doedicurus'', or ''Dædicurus'', is an extinct genus of glyptodont from South America containing one species, ''D. clavicaudatus''. Glyptodonts are a member of the family Chlamyphoridae, which also includes some modern armadillo species, ...
'' 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
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...
, ''
Glyptodon
''Glyptodon'' (from Greek for 'grooved or carved tooth': γλυπτός 'sculptured' and ὀδοντ-, ὀδούς 'tooth') is a genus of glyptodont (an extinct group of large, herbivorous armadillos) that lived from the Pleistocene, around 2.5 ...
,'' were the size of modern
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
phorusrhacids
Phorusrhacids, colloquially known as terror birds, are an extinct clade of large carnivorous flightless birds that were one of the largest species of apex predators in South America during the Cenozoic era; their conventionally accepted temporal ...
, a family of giant flightless carnivorous birds.
In physical appearance, glyptodonts superficially resembled the much earlier
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
ian
ankylosaurs and, to a lesser degree, the recently extinct giant
meiolaniid
Meiolaniidae is an extinct family of large, probably herbivorous stem-group turtles with heavily armored heads and tails known from South America and Australasia. Though once believed to be cryptodires, they are not closely related to any living ...
turtles of
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
. These are examples of the
convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
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
![The Childrens Museum of Indianapolis - Glyptodon scute - detail](https://upload.wikimedia.org/wikipedia/commons/8/8c/The_Childrens_Museum_of_Indianapolis_-_Glyptodon_scute_-_detail.jpg)
Glyptodonts were grazing
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s. Like many other
xenarthra
Xenarthra (; from Ancient Greek ξένος, xénos, "foreign, alien" + ἄρθρον, árthron, "joint") is a major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and armadillos. Ex ...
ns, they had no
incisor
Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...
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 muscles.
Extinction
Glyptodonts became extinct at the end of the
last ice age along with a large number of other
megafauna
In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
l species, including
pampatheres, the
giant ground sloth
''Megatherium'' ( ; from Greek () 'great' + () 'beast') is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene through the end of the Pleistocene. It is best known for the elephant-sized type species ' ...
s, and ''
Macrauchenia
''Macrauchenia'' ("long llama", based on the now-invalid llama genus, ''Auchenia'', from Greek "big neck") was a large, long-necked and long-limbed, three-toed native South American mammal in the order Litopterna. The genus gives its name to its ...
''. Their much smaller, more lightly armored and flexible
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 ...
relatives survived. The extinction of the glyptodonts coincided with
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
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