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'''''Glyptodon''''' (
The [[type species]], ''G. clavipes'', was described in 1839 by notable British [[Paleontology|paleontologist]] [[Richard Owen|Sir Richard Owen]]. Later in the 19th century, dozens of complete skeletons were unearthed from localities and described by paleontologists such as [[Florentino Ameghino]] and [[Hermann Burmeister]]. During this era, many species of ''Glyptodon'' were dubbed, some of them based on fragmentary or isolated remains. Fossils from North America were also assigned to ''Glyptodon'', but all of them have since been placed in the closely related genus ''[[Glyptotherium]]''. It was not until the later end of the 1900s and 21st century that full review of the genus came about, restricting ''Glyptodon'' to just five species under one genus.
Glyptodonts were typically large,
Glyptodonts existed for millions of years, though ''Glyptodon'' itself was one its last surviving members. ''Glyptodon'' was one of many South American [[megafauna]], with many native groups such as [[Notoungulata|notoungulates]] and ground sloths reaching immense sizes. ''Glyptodon'' had a mixed diet of grasses and other plants, instead living at the edge forests and grasslands where the shrubbery was lower. ''Glyptodon'' had a wide muzzle, an adaptation for bulk feeding. The armor could have protected the animal from predators, of which many coexisted with ''Glyptodon'', including the "saber-tooth cat" ''[[Smilodon]]'', the large [[Canidae|canid]] ''[[Protocyon]]'', and the giant bear ''[[Arctotherium]]''.
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=== Confusion with ''Megatherium'' ===
[[File:Georges_Cuvier.jpg|left|thumb|224x224px|[[Georges Cuvier]] (
The history and taxonomy of ''Glyptodon'' is storied and convoluted, as it involved confusion with other genera and [[Nomen dubium|dubious]] species, as well as a lack of detailed data. The first recorded discovery of ''Glyptodon'' was as early as 1814 when Uruguayan priest, scientist, soldier, and later politician [[Dámaso Antonio Larrañaga]] (
Larrañaga wrote to French scientist [[Augustin Saint-Hilaire|Auguste Saint Hilaire]] about the discovery, and the letter was reproduced by Cuvier in 1823 in the second volume of his landmark book ''Recherches sur les ossemens fossiles''.<ref name="Cuvier-1823">{{Cite book |last=Cuvier |first=Georges |url=https://books.google.com/books?id=xqZAAAAAcAAJ&dq=Cuvier,+G.+1824.+Recherches+sur+les+Ossemens+Fossiles,+nouvelle+edition.+G.+Dufour+et+E.+D'Ocagne,+Paris,+547+pp.&pg=PA1 |title=Recherches sur les ossemens fossiles |date=1823 |publisher=chez G. Dufour et E. d'Ocagne |language=fr}}</ref> Larrañaga also noted that similar fossils had been found in "analogous strata near Lake Merrim, on the frontier of the Portuguese colonies ([[South Region, Brazil|southern Brazil]])."<ref name="Cuvier-1823" /><ref name="Owen-1855" /> These fossils were also likely those of glyptodontines, possibly the closely related ''[[Hoplophorus]]''.<ref name="Porpino-2010">{{Cite journal |last1=Porpino |first1=Kleberson de O. |last2=Fernicola |first2=Juan C. |last3=Bergqvist |first3=Lílian P. |date=2010-05-18 |title=Revisiting the intertropical Brazilian species Hoplophorus euphractus (Cingulata, Glyptodontoidea) and the phylogenetic affinities of Hoplophorus
Another work on the armored ''Megatherium'' hypothesis was published in 1833 by Berlin scientist E. D'Alton, who described more of the material sent by Sellow, including portions of the limbs, [[Manus (anatomy)|manus]], and [[shoulder girdle]]. D'Alton recognized the great similarities of the fossils to ''Dasypus'' and speculated that it was a giant armadillo, contrary to the notion that they were from ''Megatherium''. Despite this, D'Alton did not erect a new name for the fossils and instead wrote that additional material was necessary to distinguish it from other armadillos. D'Alton did not mention ''Megatherium'' or its osteoderms in the paper, but he implied that all of the "''Megatherium'' armor" was instead from his armadillo. This hypothesis was supported by Laurillard in 1836, who mentioned that a plaster cast of a large armadillo carapace represented a distinct taxon from ''Megatherium'' and that the armor referred to the sloth was instead from an armadillo.<ref name="Huxley-1865" />
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=== Richard Owen and referred species ===
[[File:Glyptodon_Owen_1839.png|left|thumb|[[Richard Owen]]'s 1838 reconstruction of a ''Glyptodon'' skeleton; with the namesake tooth on the right|alt=Richard Owen's reconstruction of Glyptodon from 1838.|250x250px]]
In 1838, British diplomat [[Woodbine Parish|Sir Woodbine Parish]] (1796–1882) was sent an isolated [[Molar (tooth)|molariform]] and a letter about the discovery of several large fossils from the [[Matanza River]] in [[Buenos Aires Province|Buenos Aires]], Argentina that dated to the Pleistocene.<ref name="Owen">Owen, R. (1841). VI.—Description of a Tooth and Part of the Skeleton of the Glyptodon clavipes, a large Quadruped of the Edentate Order, to which belongs the Tesselated Bony Armour described and figured by Mr. Clift in the former Volume of the Transactions of the Geological Society; with a consideration of the question whether the Megatherium possessed an analogous Dermal Armour. ''Transactions of the Geological Society of London'', ''6''(1), 81-106.</ref><ref name="Cuadrelli-2018">{{Cite journal |last1=Cuadrelli |first1=Francisco |last2=Zurita |first2=Alfredo E. |last3=Toriño |first3=Pablo |last4=Miño-Boilini |first4=Ángel R. |last5=Rodríguez-Bualó |first5=Santiago |last6=Perea |first6=Daniel |last7=Acuña Suárez |first7=Gabriel E. |date=2018-09-03 |title=Late Pleistocene Glyptodontinae (Mammalia, Xenarthra, Glyptodontidae) from southern South America: a comprehensive review
Cuadrelli ''et al'' (2018) designated the species a ''[[species inquirenda]]'' due to this issue and commented that more analyses are necessary.<ref name="Cuadrelli-2018" /> In 1860, Signor Maximo Terrero collected a partial skeleton, including a skull and carapace, of ''G. clavipes'' from the [[Salado River (Argentina)|River Salado]] in southern Buenos Aires and dated to the Pleistocene. These fossils were also sent to the Royal College of Surgeons, where they were described in detail by British paleontologist [[Thomas Henry Huxley]] (1825–1895) in 1865 during a comprehensive review of the taxon.<ref name="Huxley-1865" /> This skeleton was also destroyed during WWII, but Huxley published several illustrations that presented great amounts of new information on the taxon.<ref name="Huxley-1865" /><ref name=":1">{{Cite journal |last=Huxley |first=Thomas Henry |date=1862-01-01 |title=Description of a New Specimen of Glyptodon, Recently Acquired by the Royal College of Surgeons of England |journal=Proceedings of the Royal Society of London |volume=12 |pages=316–326 |doi=10.1098/rspl.1862.0071 |jstor=112260 |doi-access=free}}</ref>
Later in 1845, many more fossils found by Parish from Pleistocene layers in Argentina were named as new species of ''Glyptodon'' by Owen: ''G. ornatus, G. reticulatus, G. tuberculatus'', and ''G. clavicaudatus'' in 1847. Of these additional species, only ''G. reticulatus'' is still considered a valid species of ''Glyptodon'' as ''G. ornatus'' was reassigned to the genus ''[[Neosclerocalyptus]],''<ref>Paula Couto, C. D. (1957). Sôbre um gliptodonte do Brasil. ''Boletim Divisão de Geologia e Mineralogia'', ''165'', 1-37.</ref> ''G. tuberculatus'' to ''Panochthus'',<ref name="Burmeister-2">Burmeister, G. (1866). Lista de los mamíferos fósiles del terreno diluviano. In ''Anales del Museo Público de Buenos Aires'' (Vol. 1, No. 3, pp. 121-232).</ref> and ''G. clavicaudatus'' to ''[[Doedicurus]]''.<ref>Burmeister, G. Burmeister 1870–1874. ''Monografia de los glyptodontes en el Museo Público de Buenos Aires. Anales del Museo Público de Buenos Aires'', ''2'', 1-412.</ref> ''G. reticulatus'' was named on the basis of several carapace fragments that had also been recovered from the Matanza River, but they lack detailed locality information and the fossils too were destroyed during WWII. The fragments were cast by the NHMUK as well, being used to diagnose the species.<ref name="Zurita-2018">{{Cite journal |last1=Zurita |first1=Alfredo Eduardo |last2=Gillette |first2=David D. |last3=Cuadrelli |first3=Francisco |last4=Carlini |first4=Alfredo Armando |date=2018-06-01 |title=A tale of two clades: Comparative study of Glyptodon Owen and Glyptotherium Osborn (Xenarthra, Cingulata, Glyptodontidae) |url=https://www.sciencedirect.com/science/article/pii/S0016699517301870 |journal=Geobios |language=en |volume=51 |issue=3 |pages=247–258 |doi=10.1016/j.geobios.2018.04.004 |bibcode=2018Geobi..51..247Z |hdl=11336/83593 |s2cid=134450624 |issn=0016-6995}}</ref>
Other paleontologists also started erecting names for ''Glyptodon'' species after the 1840s, but many of them are now seen as dubious, species inquirenda, or synonymous with previously named species.<ref name="Cuadrelli-2020">{{Cite journal |last1=Cuadrelli |first1=Francisco |last2=Zurita |first2=Alfredo E. |last3=Toriño |first3=Pablo |last4=Miño-Boilini |first4=Ángel R. |last5=Perea |first5=Daniel |last6=Luna |first6=Carlos A. |last7=Gillette |first7=David D. |last8=Medina |first8=Omar |date=2020-09-16 |title=A new species of glyptodontine (Mammalia, Xenarthra, Glyptodontidae) from the Quaternary of the Eastern Cordillera, Bolivia: phylogeny and palaeobiogeography
=== Reassessment and ''Glyptotherium'' ===
In the 1950s, Argentine paleontologist [[Alfredo Castellanos]] (
Another ''Glyptodon'' species was described in 2020 called ''G. jatunkhirkhi'' by several authors led by Argentine zoologist [[Francisco Cuadrelli]] on the basis of an individual preserving a nearly complete carapace, several caudal rings, and a pelvis that had been collected from [[Yamparáez Province|Yamparaez]], {{Convert|24|km|mi}} southeast of the Bolivian city of [[Sucre]]. The strata they were found in was made up of fluvial, sandy sediments that dated to the [[Late Pleistocene]] from elevations as high as {{Convert|4100-2500|m|ft}} above sea level.<ref name="Cuadrelli-2020" /> Several additional paratypes were referred to the species from other Late Pleistocene sites in [[Cordillera Oriental (Bolivia)|Eastern Cordillera]], Bolivia including a nearly complete skull and several osteoderms.<ref name="Cuadrelli-2020" /> In a phylogenetic analysis conducted by Cuadrelli ''et al''., 2020, ''G. jatunkhirki'' was recovered as the most basal ''Glyptodon'' species, despite being the same age as the more derived species ''G. clavipes.''
Fossils from North America were also described and referred to ''Glyptodon'' starting in 1875, when civil engineers J. N. Cuatáparo and Santiago Ramírez collected a skull, nearly complete carapace, and associated postcranial skeleton of a glyptodontine from a drainage canal near [[Tequixquiac]], [[Mexico]], the fossils coming from the [[Rancholabrean|Rancholabrean stage]] of the Pleistocene.<ref>Cuatáparo, J. N., & Ramírez, S. (1875). ''Descripción de un mamífero fósil de especie desconocida perteneciente al género" Glyptodon": encontrado entre las capas post-terciarias de Tequisquiac, en el Distrito de Zumpango''. F. Diaz de Leon.</ref><ref name="Zurita-2018" /> These fossils were the first found of glyptodontines in North America and were named as a new species of ''Glyptodon'', ''G. mexicanum'', but the fossils have since been lost and the species was synonymized with ''Glyptotherium cylindricum''.<ref name="Zurita-2018" /><ref name="Gillette">{{cite journal |last1=Gillette |first1=David D. |last2=Ray |first2=Clayton E. |title=Glyptodonts of North America |journal=Smithsonian Contributions to Paleobiology |date=1981 |issue=40 |pages=1–255 |url=https://repository.si.edu/bitstream/handle/10088/1966/SCtP-0040-Lo_res.pdf?sequence=2&isAllowed=y |doi=10.5479/si.00810266.40.1}}</ref> Several other North American glyptodontine species were named throughout the late 19th-early 20th century, typically based on fragmentary osteoderms. All North American and Central American fossils of glyptodontines have since been referred to the closely related genus ''Glyptotherium'', which was named in 1903 by American paleontologist [[Henry Fairfield Osborn]].<ref>{{Cite book |last=Osborn |first=Henry Fairfield |url=https://books.google.com/books?id=BMUrAAAAYAAJ&dq=glyptotherium+texanum&pg=PA489 |title=Glyptotherium Texanum, a New Glyptodont, from the Lower Pleistocene of Texas |date=1903 |publisher=order of the Trustees, American Museum of Natural History |language=en}}</ref>
== Taxonomy ==
''Glyptodon'' is the type genus of Glyptodontinae, an extinct [[subfamily]] of large, heavily armored armadillos that first evolved in the [[Eocene|Late Eocene]] (ca. 33.5 mya) and went extinct in the [[Greenlandian|Early Holocene]] during the [[Late Pleistocene extinctions]] (ca. 7,000 years ago).<ref name="Cuadrelli-2020" /><ref name="Delsuc20162">{{cite journal |last1=Delsuc |first1=F. |last2=Gibb |first2=G.C. |last3=Kuch |first3=M. |last4=Billet |first4=G. |last5=Hautier |first5=L. |last6=Southon |first6=J. |last7=Rouillard |first7=J.-M. |last8=Fernicola |first8=J.C. |last9=Vizcaíno |first9=S.F. |last10=MacPhee |first10=R.D.E. |last11=Poinar |first11=H.N. |year=2016 |title=The phylogenetic affinities of the extinct glyptodonts |journal=Current Biology |volume=26 |issue=4 |pages=R155–R156 |doi=10.1016/j.cub.2016.01.039 |pmid=26906483 |doi-access=free|bibcode=2016CBio...26.R155D }}</ref> Owen recognized that ''Glyptodon'' was an [[Xenarthra|edentate]], but did not recognize it as being a part of a new subfamily as there were no other recognized glyptodontines in 1839.<ref name="Owen-2" /> The family Glyptodontidae was not named until 1869 by [[John Edward Gray]], who included the genera ''Glyptodon, Panochthus,'' and ''Hoplophorus'' within the group and believed that it was diagnosed by an immovable carapace that was fused to the pelvis.<ref>Gray, J. E. (1869). ''Catalogue of carnivorous, pachydermatous, and edentate Mammalia in the British Museum''. order of the Trustees.</ref> However, Hermann Burmeister proposed the name Biloricata for the family, believing that glyptodontines possessed a ventral [[Turtle shell|plastron]] (bottom shell) and could pull their heads inside their carapaces like turtles. This name lost all use and his theory has not been supported.<ref name="Burmeister" /><ref name="Burmeister-2" /> The internal phylogenetics of Glyptodontidae was analyzed in greater detail by Florentino Ameghino during his descriptions of earlier members of the clade, which proposed that ''Glyptodon'' was descended from earlier genera.<ref name="Ameghino" /><ref name="Soibelzon-2006" />
Glyptodontinae was classified in its own family or even superfamily until in 2016, when [[ancient DNA]] was extracted from the carapace of a 12,000 year old ''Doedicurus'' specimen, and a nearly complete [[mitochondrial genome]] was reconstructed (76x [[Coverage (genetics)|coverage]]). Comparisons with those of modern armadillos revealed that glyptodonts diverged from [[Tolypeutinae|tolypeutine]] and [[Chlamyphorinae|chlamyphorine]] armadillos approximately 34 million years ago in the [[Priabonian|late Eocene]].<ref name="Mitchell2016">{{cite journal |last1=Mitchell |first1=K.J. |last2=Scanferla |first2=A. |last3=Soibelzon |first3=E. |last4=Bonini |first4=R. |last5=Ochoa |first5=J. |last6=Cooper |first6=A. |year=2016 |title=Ancient DNA from the extinct South American giant glyptodont ''Doedicurus'' sp. (Xenarthra: Glyptodontidae) reveals that glyptodonts evolved from Eocene armadillos |url=http://sedici.unlp.edu.ar/handle/10915/101557 |journal=Molecular Ecology |volume=25 |issue=14 |pages=3499–3508 |doi=10.1111/mec.13695 |pmid=27158910|bibcode=2016MolEc..25.3499M |s2cid=3720645 }}</ref><ref name="Delsuc20162" /> This prompted moving them from their own family, Glyptodontidae, to the subfamily Glyptodontinae within the [[Extant taxon|extant]] [[Chlamyphoridae]].<ref name="Delsuc20162" /> Based on this and the fossil record, glyptodonts would have evolved their characteristic shape and large size ([[gigantism]]) quite rapidly, possibly in response to the cooling, drying climate and expansion of open savannas.<ref name="Mitchell2016" /> Chylamyphoridae is a group in the order Cingulata, which includes all extant armadillos in addition to other fossil groups like [[Pachyarmatheriidae]] and [[Pampatheriidae|Pampatheridae]]. Cingulata is itself within the basal mammal group Xenarthra, which includes an array of American mammal groups like [[Anteater|Vermilingua]] (anteaters) and [[Sloth|Folivora]] (sloths and ground sloths) in the order [[Pilosa]]. The following phylogenetic analysis was conducted by Frédéric Delsuc and colleagues in 2016 and represents the phylogeny of Cingulata using ancient DNA from ''Doedicurus'' to determine the position of it and other Glyptodonts:<ref name="Mitchell2016" /><ref name="Delsuc20162" />
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}}
}}|style=font-size:90%;line-height:100%;|label1= [[Cingulata]] }}
[[File:Richard-owen2.jpg|thumb|Portrait of [[Richard Owen|Sir Richard Owen]] (
The internal phylogeny of Glyptodontinae is convoluted and in flux, with many species and families erected based on fragmentary or undiagnostic material that lacks comprehensive review.<ref name="Zurita-2011-2" /><ref name="Porpino-2010" /> Glyptodontinae's tribes were long-considered subfamilies before the 2016 analysis.<ref name="Mitchell-2016">{{Cite journal |last1=Mitchell |first1=Kieren J. |last2=Scanferla |first2=Agustin |last3=Soibelzon |first3=Esteban |last4=Bonini |first4=Ricardo |last5=Ochoa |first5=Javier |last6=Cooper |first6=Alan |date=2016 |title=Ancient DNA from the extinct South American giant glyptodont Doedicurus sp. (Xenarthra: Glyptodontidae) reveals that glyptodonts evolved from Eocene armadillos |url=https://onlinelibrary.wiley.com/doi/10.1111/mec.13695 |journal=Molecular Ecology |language=en |volume=25 |issue=14 |pages=3499–3508 |doi=10.1111/mec.13695|pmid=27158910 |bibcode=2016MolEc..25.3499M |s2cid=3720645 }}</ref> One tribe, Glyptodontini (typically labeled Glyptodontinae) is a group of younger, larger glyptodontines that evolved in the [[Middle Miocene]] (ca. 13 mya) with ''[[Boreostemma]]'',<ref>{{Cite journal |last1=Zurita |first1=Alfredo E. |last2=González Ruiz |first2=Laureano R. |last3=Gómez-Cruz |first3=Arley J. |last4=Arenas-Mosquera |first4=Jose E. |date=2013-05-01 |title=The most complete known Neogene Glyptodontidae (Mammalia, Xenarthra, Cingulata) from northern South America: taxonomic, paleobiogeographic, and phylogenetic implications
Below is the phylogenetic analysis conducted by Cuadrelli ''et al''., 2020 of Glyptodontinae, with Glyptodontidae as a family instead of subfamily, that focuses on advanced glyptodonts:<ref name="Cuadrelli-2020" />
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|1={{clade
|1={{clade
|1=''[[
|2=''[[
|2={{clade
|1={{clade
|1=''[[Glyptotherium|Glyptotherium cylindricum]]''
|2=''[[
|2={{clade
|1='''''Glyptodon jatunkhirkhi'''''
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|1={{clade
|1=''[[Eleutherocercus|Eleutherocercus antiquus]]''
|2=''[[
|2={{clade
|label1=Neosclerocalyptini
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|2={{clade
|1=''[[Panochthus|Panochthus intermedius]]''
|2=''[[
}} }} }} }} }} }} }} }} }} }} }} }} }}|style=font-size:85%;line-height:80%|label1='''Chlamyphoridae'''}}
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In the [[axial skeleton]], glyptodontines had strongly fused [[vertebra]]e and [[Pelvis|pelves]] completely connected to the carapace, traits convergently evolved in turtles.<ref name="Huxley-1865" /><ref name="Gillette" /> The large tails of glyptodontines likely served as a counterbalance to the rest of the body and ''Glyptodon''<nowiki/>'s caudal armor ended in a blunt tube that was composed of two concentric tubes fused together, in contrast to those of mace-tailed glyptodontines like ''Neosclerocalyptus'' and ''Doedicurus''.<ref name="Gillette" /> ''Glyptodon'' had graviportal (weight-bearing), short limbs that are very similar to those in other glyptodontines, being indistinguishable from those of some other taxa.<ref name="Zurita-2018" /> The digits of ''Glyptotherium'' are very stout and adapted for weight-bearing, though some preserve large claw sheaths that had an intermediate morphology between claws and hooves.<ref name="Gillette" />
During the Pleistocene, the diversity of glyptodontines diminished but body size increased, with the largest known glyptodont, ''Doedicurus,'' evolving in the Pleistocene.<ref name="Carlini-2022">{{Cite journal |last1=Carlini |first1=Alfredo A. |last2=Carrillo-Briceño |first2=Jorge D. |last3=Jaimes |first3=Arturo |last4=Aguilera |first4=Orangel |last5=Zurita |first5=Alfredo E. |last6=Iriarte |first6=José |last7=Sánchez-Villagra |first7=Marcelo R. |date=2022-06-16 |title=Damaged glyptodontid skulls from Late Pleistocene sites of northwestern Venezuela: evidence of hunting by humans? |journal=[[Swiss Journal of Palaeontology]] |volume=141 |issue=1 |pages=11 |doi=10.1186/s13358-022-00253-3 |s2cid=249681104 |issn=1664-2384 |doi-access=free |bibcode=2022SwJP..141...11C }}</ref><ref>{{Citation |last=Defler |first=Thomas |title=The Xenarthrans: Armadillos, Glyptodonts, Anteaters, and Sloths |date=2019
=== Skull, mandible, and dentition ===
[[File:Craneo de Glyptodon.jpg|alt=Glyptodon skull|left|thumb|235x235px|Skull of ''Glyptodon'' in side view.]]
Glyptodont dentition contains entirely [[hypsodont]] molariforms, which have one of the most extreme examples of hypsodonty known from terrestrial mammals.{{Sfn|Gillette|Ray|1981|p=200}} The dentition is typical of other armadillos, but is fluted on each side by deep grooves. The anterior teeth were compressed, while the posterior teeth were cylindrical.<ref>{{Cite journal |last=Flower |first=W.H. |date=1871 |title=Professor Flower's Hunterian Lectures On The Teeth and Allied Organs In The Mammalia |journal=The British Medical Journal}}</ref> Glyptodont skulls have several unique features; the [[maxilla]] and [[Palate|palatine]] are enlarged vertically to make space for the molariforms, while the braincase is brachycephalic, short and flat.{{Sfn|Gillette|Ray|1981|p=58}} In ''Glyptodon'' and many other glyptodontines, the roof of the skull was covered by a shield composed of polygonal, irregular osteoderms that were variable in size and ankylosed together to form a robust cephalic shield that had a smoothly convex exterior surface without ornamentation.<ref name="Soibelzon-2006" /> Each osteoderm has a rugose and slightly convex dorsal surface, with ornamentation pattern defined by a central figure, slightly elevated and surrounded by an area without peripheral figures or [[Vertebra|foramina]]. Sutures separating osteoderms are well marked, as in ''Panochthus.''<ref name="Soibelzon-2006" /><ref name="Carlini-2008">{{Cite journal |last1=Carlini |first1=Alfredo A. |last2=Zurita |first2=Alfredo E. |last3=Aguilera |first3=Orangel A. |date=2008 |title=North American Glyptodontines (Xenarthra, Mammalia) in the Upper Pleistocene of northern South America
The nasal passage was reduced with heavy [[muscle]] attachments for some unknown purpose. Some have speculated that the muscle attachments were for a [[proboscis]], or [[Torso|trunk]], much like that of a [[tapir]] or [[elephant]]. The lower jaws were very deep and helped support massive chewing muscles to help chew coarse fibrous plants. Some paleontologists have proposed that ''Glyptodon'' and some glyptodontines also had a [[proboscis]] or large snout similar to those in [[proboscidea]]ns and [[tapir]]s,{{Sfn|Gillette|Ray|1981|p=202}} but few have accepted this hypothesis.<ref name="Zurita-2011-2" /><ref name="Sergio F. Vizcaíno-2012" /> Another suggestion, made by A.E. Zurita and colleagues, is that the large nasal sinuses could be correlated with the cold arid climate of [[Pleistocene]] South America.<ref name="Sergio F. Vizcaíno-2012">{{cite journal |author1=Fernicola, Juan Carlos |author2=Néstor Toledo |author3=M. Susana Bargo |author4=Sergio F. Vizcaíno |date=October 2012 |title=A neomorphic ossification of the nasal cartilages and the structure of paranasal sinus system of the glyptodont Neosclerocalyptus Paula Couto 1957 (Mammalia, Xenarthra) |journal=Palaeontologia Electronica |volume=15 |issue=3 |pages=1–22 |doi=10.26879/333 |doi-access=free}}</ref><ref>{{cite web |author=Gillette, David D. |date=2010 |title=Glyptodonts in Arizona a saga of supercontinents, sea-floor spreading, savannas, and sabertooth cats |url=http://www.azgs.az.gov/arizona_geology/spring10/article_feature.html |access-date=25 March 2014 |publisher=Arizona Geological Survey |archive-date=29 April 2014 |archive-url=https://web.archive.org/web/20140429180717/http://www.azgs.az.gov/arizona_geology/spring10/article_feature.html |url-status=dead }}</ref> A distinctive bar of bone projects downwards on the cheek, extending over the lower jaw, perhaps providing an anchor for powerful snout muscles. In turn, the [[Infraorbital foramen|infraorbital foramina]] are narrow and not visible in anterior view in ''Glyptotherium'', but in ''Glyptodon'' they are broad and clearly visible in anterior view. In lateral view, the dorso-ventral height between the [[skull roof]] and the [[Palatine bone|palatal plane]] in ''Glyptodon'' decreases anteriorly, contrary to ''Glyptotherium''; the nasal tip is in a lower plane with respect to the [[zygomatic arch]] in ''Glyptodon'', but in ''Glyptotherium'' is higher than the zygomatic arch plane. The 1st molariform (molaiform is abbreviated as mf#) of ''Glyptodon'' is distinctly [[Cusp (anatomy)|trilobate]] (three-lobed) both lingually and labially, nearly as trilobate as the mf2; on the contrary, ''Glyptotherium'' shows a very low trilobation of mf1, which is elliptical in cross-section, the mf2 is weakly trilobate, and the mf3 is trilobate. In both genera, the mf4 to mf8 are fully trilobate and serially identical.<ref name="Zurita-2018" /> These traits separate the two genera.<ref name="Zurita-2018" /> Within the genus ''Glyptodon'' this trait varies as well, with ''G. reticulatus'' having triloby to a greater degree than ''G. munizi''.<ref name="Cuadrelli-2018" />[[File:Glyptodon_Skelett.JPG|thumb|''Glyptodon'' skeleton and shell in [[Museum für Naturkunde]], [[Berlin]]|alt=A Glyptodon skeleton and shell.|228x228px]]The [[mandible]]s of ''Glyptotherium'' and ''Glyptodon'' are very similar, but ''Glyptotherium''<nowiki/>'s mandible is smaller by about 10% in total size. The angle between the [[Occlusion (dentistry)|occlusal plane]] (part of the jaw where upper and lower teeth contact) and the anterior margin of the ascending [[Ramus mandibulae|ramus]] is approximately 60 in ''Glyptotherium,'' while it is 65° in ''Glyptodon.'' The ventral margin of the horizontal ramus is more concave in ''Glyptodon'' than in ''Glyptotherium''. The [[Mandibular symphysis|symphysis]] area is extended greatly in ''Glyptotherium'' antero-posteriorily compared to ''Glyptodon''. The mf1 is ellipsoidal in ''Glyptotherium'' and the mf2 is "submolariform", while in ''Glyptodon'' both teeth are trilobate.<ref name="Zurita-2018" />
=== Vertebrae and pelvis ===
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=== Carapace and osteoderms ===
[[File:Glyptodon asper armor.JPG|left|thumb|Close-up view of carapace|alt=Close-up view of carapace.]][[File:Armour_of_glyptodon.JPG|thumb|''Glyptodon'' carapace in [[Hungarian Natural History Museum]]|alt=A Glyptodon carapace.]]''Glyptodon''{{'}}s osteoderms were attached by [[Synostosis|synotoses]] (bony connections) 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 [[Cone|conical]]. The sulci between these raised structures were deep and wide with parallel lines.<ref name="Zurita2010">{{cite journal |last1=Zurita |first1=A. E. |last2=Soibelzon |first2=L. H. |last3=Soibelzon |first3=E. |last4=Gasparini |first4=G. M. |last5=Cenizo |first5=M. M. |last6=Arzani |first6=H. |year=2010 |title=Accessory protection structures in ''Glyptodon'' Owen (Xenarthra, Cingulata, Glyptodontidae) |journal=Annales de Paléontologie |volume=96 |issue=1 |pages=1–11 |doi=10.1016/j.annpal.2010.01.001 |bibcode=2010AnPal..96....1Z |hdl-access=free |hdl=10915/5356}}</ref> The carapace of ''Glyptodon'' was strongly elongated compared to those of ''Boreostemma'' and ''Glyptotherium,'' with the carapace being relatively 65% longer than the former and 14% than the latter. In ''Glyptodon'', the top-bottom height of the carapace represents 60% of its total length, whereas in ''Glyptotherium'' it is taller at circa 70%. The antero-posterior dorsal profile of the carapace was convex and its posterior half was higher than the anterior. The apex of the carapace was slightly displaced posteriorly in most ''Glyptodon'' species, while in ''Glyptotherium'' and ''Glyptodon jatunkhirkhi'' it was at the center of the midline. The carapace of most species of ''Glyptodon'' is arched subtly, while ''Glyptotherium'' and ''Glyptodon jatunkhirkhi''{{'}}s has a very arched back and convex pre-iliac and concave post-iliac, giving it a saddle-like overhang over the tail. ''Glyptodon'' osteoderms in the antero-lateral regions of the carapace are strongly ankylosed, giving them little flexibility, while in ''Glyptotherium'' they are less ankylosed and more flexible.<ref name="Zurita-2018" /> The osteoderms of the caudal aperture (large conical osteoderms that protect the base of the tail) are more conical in ''Glyptodon'' and more rounded in ''Glyptotherium'', though in the latter the anatomy of the caudal aperture osteoderms varies by sex while in ''Glyptodon'' it varies by age.<ref name="Zurita-2018" /><ref name="Gillette-2016">{{Cite journal |last1=Gillette |first1=David D. |last2=Carranza-Castañeda |first2=Óscar |last3=White |first3=Richard S. |last4=Morgan |first4=Gary S. |last5=Thrasher |first5=Larry C. |last6=McCord |first6=Robert |last7=McCullough |first7=Gavin |date=2016-06-01 |title=Ontogeny and Sexual Dimorphism of Glyptotherium texanum (Xenarthra, Cingulata) from the Pliocene and Pleistocene (Blancan and Irvingtonian NALMA) of Arizona, New Mexico, and Mexico
Osteoderms on the ventral side of the body were first mentioned by paleontologist Hermann Burmeister in 1866, postulating that there was a ventral plastron like in turtles based on evidence of small armor in the dermis.<ref name="Burmeister" /> This hypothesis has since been disproven, but 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, evolving in younger species like ''G. reticulatus'' . These small to medium-sized ossicles were actually embedded in the dermis and did not connect in a pattern.<ref name="Zurita2010" />
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=== Endocranial anatomy ===
[[File:Glyptodontidae brains - Gervais 1869.png|alt=Endocasts of Glyptodon and Doedicurus |left|thumb|[[Endocast]]s of ''Glyptodon'' (left) and ''Doedicurus'' (right).|256x256px]]
Several complete skulls of ''Glyptodon'' enable the endocranial anatomy to be analyzed, as well as compared to other well-preserved taxa like ''Doedicurus'' and ''Panochthus''. The brain cavities of the larger glyptodontines ''Glyptodon, Doedicurus,'' and ''Panochthus'' had a braincase volume of {{Convert|213 to 234|cm3|U.S.oz}}. The [[encephalization quotient]] of these taxa are 0.12 to 0.4, lower than most modern armadillos (0.44-1.06) and corresponds to those of pampatheres. The brain of the glyptodontines had an extensive [[olfactory bulb]] that took up between 4.8 and 9.7% of the entire brain, while around two thirds of it were occupied by the [[cerebrum]] and the rest by the [[cerebellum]]. Overall, this is akin to that of other armadillos, but in the latter the cerebrum is smaller relative to the cerebellum and the braincase's total volume. Deviating from the armadillos with their wide olfactory bulb, glyptodontines and pampatheres have elongated and triangular olfactory systems. Several other neuroanatomical characteristics differ between glyptodontines and armadillos, such as the presence of a pronounced [[Sulcus (neuroanatomy)|sulcus praesylvianus]].<ref name=":2">{{Cite journal |last1=Tambusso |first1=P Sebastián |last2=Fariña |first2=Richard A. |date=2015-09-03 |title=Digital cranial endocast of Pseudoplohophorus absolutus (Xenarthra, Cingulata) and its systematic and evolutionary implications |url=http://www.tandfonline.com/doi/full/10.1080/02724634.2015.967853 |journal=Journal of Vertebrate Paleontology |language=en |volume=35 |issue=5 |pages=e967853 |doi=10.1080/02724634.2015.967853 |bibcode=2015JVPal..35E7853T |s2cid=86537473 |issn=0272-4634}}</ref><ref name=":3">{{Cite journal |last1=Sebastián Tambusso |first1=P. |last2=Fariña |first2=Richard A. |date=2015 |title=Digital endocranial cast of Pampatherium humboldtii (Xenarthra, Cingulata) from the Late Pleistocene of Uruguay |url=https://sjpp.springeropen.com/articles/10.1007/s13358-015-0070-5 |journal=[[Swiss Journal of Palaeontology]] |language=en |volume=134 |issue=1 |pages=109–116 |doi=10.1007/s13358-015-0070-5 |bibcode=2015SwJP..134..109S |s2cid=86652394 |issn=1664-2384}}</ref>
In general, living cingulates have smaller brains than anteaters and sloths for reasons unknown. Several theories have been made as to why, such as a shorter rearing phase of offspring, dedication of resources to the development of the carapace, and other biological and functional handicaps. Members of Cingulata also tend to have extremely low metabolisms, causing less energy flow to the development of the brain's neurons. The pattern of large bodies bearing adequate protection and a reduction of intelligence is found in several other groups such as [[Ankylosauria|ankylosaurs]] and [[Stegosauria|stegosaurs]], two types of armored [[dinosaur]]. However, the carapace itself is considered as a restrictive functional component as it prohibited much neck movement and forced a reduced brain size. This reduction thus resulted in weight loss in the skull, which had a great
=== Feeding and diet ===
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Two main groups of glyptodontines can be distinguished by their feeding habits: narrow-muzzled Miocene propalaehoplophorids and wide-muzzled post-Miocene glyptodontines.<ref>{{Cite web |title=Bargo M. S. Vizcaíno S. F. — Paleobiology of Pleistocene ground sloths (Xenarthra, Tardigrada) : biomechanics, morphogeometry and ecomorphology applied to the masticatory apparatus. Ameghiniana |url=https://www.researchgate.net/publication/262718932 |access-date=2015-10-30 |website=ResearchGate}}</ref> The propalaehoplophorids were selective feeders, while the post-Miocene glyptodontines were [[bulk feeder]]s (obtain nutrients by consuming an entire plant). However, because of their body form and fusion of the cervical vertebrae glyptodontines would have needed to forage near the ground. Their craniomandibular joint limited their jaw to side-to-side movement.<ref name="Fariña-2001">{{Cite journal |last=Fariña |first=R.A. |date=2001 |title=Carved Teeth and Strange Jaws: How Glyptodonts Masticated. |url=https://www.app.pan.pl/archive/published/app46/app46-219.pdf |journal=Acta Palaeontologica Polonica}}</ref> ''Glyptodon''<nowiki/>'s jaws had large ridges of osteodentine which could effectively be used to grind food particles before shearing and pushing them via the constant motion of the mandible.<ref name="Fariña-2001" /> They had a well-developed snout musculature, along with a mobile neck region that helped them secure food.<ref name="Gillette1981">{{Cite journal |last=Gillette |first=R. |date=21 December 1981 |title=Glyptodonts of North America |url=http://www.sil.si.edu/smithsoniancontributions/Paleobiology/pdf_lo/SCtP-0040.pdf |journal=Smithsonian Publications |access-date=2015-10-29}}</ref> The hyoid shows a robust design that suggests ''Glyptodon'' had a large and robust tongue, which may have aided in food intake and processing.<ref>{{Cite journal |last1=Pérez |first1=Leandro M. |last2=Toledo |first2=Néstor |last3=De Iuliis |first3=Gerardo |last4=Bargo |first4=M. Susana |last5=Vizcaíno |first5=Sergio F. |date=2010 |title=Morphology and function of the hyoid apparatus of fossil xenarthrans (mammalia) |url=https://onlinelibrary.wiley.com/doi/10.1002/jmor.10859 |journal=Journal of Morphology |language=en |volume=271 |issue=9 |pages=1119–1133 |doi=10.1002/jmor.10859|pmid=20730924 |s2cid=8106788 }}</ref><ref>Zamorano, M., Scillato-Yané, G. J., Soibelzon, E., Soibelzon, L. H., Bonini, R., & Rodriguez, S. (2018). [https://www.researchgate.net/profile/Martin-Zamorano-2/publication/324703634_Hyoid_apparatus_of_Panochthus_sp_Xenarthra_Glyptodontidae_from_the_Late_Pleistocene_of_the_Pampean_Region_Argentina_Comparative_description_and_muscle_reconstruction/links/5ade1b23aca272fdaf88f295/Hyoid-apparatus-of-Panochthus-sp-Xenarthra-Glyptodontidae-from-the-Late-Pleistocene-of-the-Pampean-Region-Argentina-Comparative-description-and-muscle-reconstruction.pdf Hyoid apparatus of Panochthus sp.(Xenarthra; Glyptodontidae) from the Late Pleistocene of the Pampean region (Argentina). Comparative description and muscle reconstruction.] ''Neues Jahrbuch für Geologie und Paläontologie Abhandlungen'', ''288'', 205-219.</ref>
Like most other xenarthrans, glyptodontines had lower energy requirements than contemporary mammal groups.<ref>{{Cite journal |last1=Vizcaíno |first1=Sergio F. |last2=Cassini |first2=Guillermo H. |last3=Fernicola |first3=Juan C. |last4=Bargo |first4=M. Susana |year=2011 |title=Evaluating Habitats and Feeding Habits Through Ecomorphological Features in Glyptodonts (Mammalia, Xenarthra) |url=https://www.researchgate.net/publication/257931077 |journal=Ameghiniana |pages=305–319 |doi=10.5710/AMGH.v48i3(364) |hdl=11336/69574 |access-date=2015-10-29 |s2cid=85793531}}</ref> The stomachs of glyptodontids are mysterious due to being entirely herbivorous, in contrast to modern, omnivorous armadillos which have simple stomachs instead of the chambered ones of sloths.<ref name="Bocherens-2017">{{Cite journal |last1=Bocherens |first1=Hervé |last2=Cotte |first2=Martin |last3=Bonini |first3=Ricardo A. |last4=Straccia |first4=Pablo |last5=Scian |first5=Daniel |last6=Soibelzon |first6=Leopoldo |last7=Prevosti |first7=Francisco J. |date=2017 |title=Isotopic insight on paleodiet of extinct Pleistocene megafaunal Xenarthrans from Argentina |url=https://linkinghub.elsevier.com/retrieve/pii/S1342937X16304944 |journal=Gondwana Research |language=en |volume=48 |pages=7–14 |doi=10.1016/j.gr.2017.04.003|bibcode=2017GondR..48....7B |hdl=11336/56592 }}</ref> This in conjugation with the proposed idea that aquatic grazing may have caused the isotopes strongly associated with herbivory observed in ''Glyptodon'' fossils.<ref name="Bocherens-2017" /> However, aquatic grazing in ''Glyptodon'' is little supported<ref>Fariña, R.A., 1995. Limb bone strength and habits in large glyptodonts. ''Lethaia'', 28: 189-196.</ref> though more backing for this hypothesis has been found in the related ''Glyptotherium''.<ref>{{Cite journal |last1=Lessa |first1=Carlos Micael Bonfim |last2=Gomes |first2=Verônica Santos |last3=Cherkinsky |first3=Alexander |last4=Dantas |first4=Mário André Trindade |date=2021-12-01 |title=Isotopic paleoecology (δ13C, δ18O) of two megamammals assemblages from the late pleistocene of Brazilian intertropical region |url=https://www.sciencedirect.com/science/article/pii/S0895981121004223 |journal=Journal of South American Earth Sciences |language=en |volume=112 |pages=103576 |doi=10.1016/j.jsames.2021.103576 |bibcode=2021JSAES.11203576L |s2cid=244181217 |issn=0895-9811}}</ref><ref>{{Cite journal |last1=Omena |first1=Érica Cavalcante |last2=Silva |first2=Jorge Luiz Lopes da |last3=Sial |first3=Alcides Nóbrega |last4=Cherkinsky |first4=Alexander |last5=Dantas |first5=Mário André Trindade |date=2021-10-03 |title=Late Pleistocene meso-megaherbivores from Brazilian Intertropical Region: isotopic diet ( δ 13 C), niche differentiation, guilds and paleoenvironmental reconstruction ( δ 13 C, δ 18 O) |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2020.1789977 |journal=Historical Biology |language=en |volume=33 |issue=10 |pages=2299–2304 |doi=10.1080/08912963.2020.1789977 |bibcode=2021HBio...33.2299O |s2cid=225543776 |issn=0891-2963}}</ref><ref name="Gillette" /> A carbon isotopic analysis of ''Glyptodon'' bones by França ''et al'' (2015) found that it consumed a variety of both [[C3 carbon fixation|C3]] plants and [[C4 carbon fixation|C4]] grasses at lower latitudes while it ate exclusively C3 grasses at higher ones, implying an ecological shift based on the climate. A 2012 analysis of isotopes supports this, but the isotopic results are not backed by morphological evidence.<ref name="Fariña-2001" /> The isotopic conclusion would place ''Glyptodon'' as a mixed browser in most environments, similar to some other glyptodontines.<ref name="França-2015">{{Cite journal |last1=França |first1=Lucas de Melo |last2=de Asevedo |first2=Lidiane |last3=Dantas |first3=Mário André Trindade |last4=Bocchiglieri |first4=Adriana |last5=Avilla |first5=Leonardo dos Santos |last6=Lopes |first6=Renato Pereira |last7=da Silva |first7=Jorge Luíz Lopes |date=2015-01-01 |title=Review of feeding ecology data of Late Pleistocene mammalian herbivores from South America and discussions on niche differentiation |url=https://www.sciencedirect.com/science/article/pii/S0012825214001858 |journal=Earth-Science Reviews |language=en |volume=140 |pages=158–165 |doi=10.1016/j.earscirev.2014.10.006 |bibcode=2015ESRv..140..158F |issn=0012-8252}}</ref><ref name="Domingo-2012">{{Cite journal |last1=Domingo |first1=Laura |last2=Prado |first2=José Luis |last3=Alberdi |first3=María Teresa |date=2012-11-08 |title=The effect of paleoecology and paleobiogeography on stable isotopes of Quaternary mammals from South America |url=https://www.sciencedirect.com/science/article/pii/S0277379112003307 |journal=Quaternary Science Reviews |language=en |volume=55 |pages=103–113 |doi=10.1016/j.quascirev.2012.08.017 |bibcode=2012QSRv...55..103D |issn=0277-3791}}</ref> The 2012 paper also noted that ''Glyptodon'' may have had a more flexible diet than previously imagined,<ref>Pomi, L. H. (2008). [http://www.scielo.org.ar/scielo.php?pid=S0002-70142008000200019&script=sci_arttext&tlng=pt Una nueva asociación de vertebrados fósiles de Edad Ensenadense (Plioceno tardío-Pleistoceno medio) de la provincia de Buenos Aires, Argentina.] ''Ameghiniana'', ''45''(2), 503-510.</ref> with a mix of slightly wooded and slightly open habitats as implied by the consumption of C3 and C4 material.<ref name="Domingo-2012" /><ref name="Vizcaíno-2011" /> The C4 plants include groups like [[Poaceae]], [[Cyperaceae]], [[Asteraceae]], and [[Amaranthaceae]] based on palynological evidence, meaning that ''Glyptodon'' likely ate C4 [[flowering plant]]s in addition to C3 grasses.<ref>{{Cite journal |last=Sage |first=Rowan F. |date=2004 |title=The evolution of C 4 photosynthesis |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2004.00974.x |journal=New Phytologist |language=en |volume=161 |issue=2 |pages=341–370 |doi=10.1111/j.1469-8137.2004.00974.x |pmid=33873498 |issn=0028-646X}}</ref><ref name="França-2015" /> A mesowear analysis supported their conclusion, however, finding that mixed-feeding causing blunt wear that suggests a more abrasion-dominated diet. This is similar to that of ''Neosclerocalyptus'', but in contrast to ''Hoplophorus'' which had sharper wear ends. ''Neosclerocalyptus'' favored more open environments despite this, as found by isotopic studies.<ref name="Zurita-2011-2" /><ref name="Vizcaíno-2011" /> The mesowear angles of ''Glyptodon'' were noted to possess a [[Multimodal distribution|bimodal distribution]], implying a difference between populations, sexes, or species in diet.<ref name="Saarinen-2017" />
=== Intraspecific combat ===
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=== Posture ===
Several interpretations of glyptodontine posture have been made,<ref>{{Cite journal |last1=Amson |first1=Eli |last2=Nyakatura |first2=John A. |date=2018-12-01 |title=The Postcranial Musculoskeletal System of Xenarthrans: Insights from over Two Centuries of Research and Future Directions
=== Sexual dimorphism and group behavior ===
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== Distribution and paleoecology ==
[[File:Glyptodonts.jpg|thumb|right|The contemporary [[glyptodonts]] ''Glyptodon'', ''[[Doedicurus]]'', and ''[[Panochthus]]'']]
''Glyptodon'' is one of the most common Pleistocene glyptodontines with a large range from the lowland [[Pampas]] to the towering [[Andes|Andean Mountains]] of Peru and Bolivia, some fossils found at elevations reaching over {{Convert|4100|m|ft}} above sea level.<ref>{{Cite journal |last1=Pujos |first1=François |last2=Salas |first2=Rodolfo |date=2004-08-01 |title=A systematic reassessment and paleogeographic review of fossil Xenarthra from Peru |url=https://journals.openedition.org/bifea/5746 |journal=Bulletin de l'Institut français d'études andines |volume=33 |language=en |issue=2 |pages=331–377 |doi=10.4000/bifea.5746 |s2cid=130927479 |issn=0303-7495}}</ref><ref name="Zurita-2017">{{Cite journal |last1=Zurita |first1=Alfredo Eduardo |last2=Zamorano |first2=Martín |last3=Scillato-Yané |first3=Gustavo Juan |last4=Fidel |first4=Sergio |last5=Iriondo |first5=Martín |last6=Gillette |first6=David D. |date=2017-11-17 |title=A new species of Panochthus Burmeister (Xenarthra, Cingulata, Glyptodontidae) from the Pleistocene of the Eastern Cordillera, Bolivia |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2016.1278443 |journal=Historical Biology |language=en |volume=29 |issue=8 |pages=1076–1088 |doi=10.1080/08912963.2016.1278443 |bibcode=2017HBio...29.1076Z |s2cid=91031708 |issn=0891-2963}}</ref><ref name="Cuadrelli-2020" /> Only ''G. munizi'' is found in the early-middle Pleistocene, whereas other species are younger.<ref name="Soibelzon-2006" /><ref name="Cuadrelli-2020" /> ''G. reticulatus'' is specifically noted to be known from 60ka to as recent as 7ka possibly, though confirmed records only extend to 11 ka.<ref name="Ubilla-2018" /> The genus had a generalist diet, which allowed it to fill niches in areas that were inaccessible by grazing genera, with ''G. reticulatus'' representing up to 90% of the glyptodontine fossils in the Tarija Valley of Bolivia.<ref name="Zurita" /> However, in regions such as the Pampas, Mesopotamia, and Uruguay, an array of glyptodontines are known.<ref name="Ubilla-2018" /><ref name="Cuadrelli-2018" /> Further evidence of ''Glyptodon''{{'}}s adaptability is found in the Pampas, which were semihumid and temperate from 30,000 to 11,000 ka, alternating between the [[Wet season|rainy]] and [[dry season]]s, over a large area consisting mostly of grasslands dotted with forests and mixed shrubbery.<ref>Blasi, A., Castiñeira Latorre, C., Del Puerto, L., Prieto, A. R., Fucks, E., De Francesco, C., ... & Young, A. (2010). [http://www.scielo.org.ar/pdf/lajsba/v17n2/v17n2a02.pdf Paleoambientes de la cuenca media del río Luján (Buenos Aires, Argentina) durante el último período glacial (EIO 4-2).] ''Latin American journal of sedimentology and basin analysis'', ''17''(2), 85-111.</ref><ref>{{Cite journal |last1=Prado |first1=José L. |last2=Martinez-Maza |first2=Cayetana |last3=Alberdi |first3=María T. |date=2015-05-01 |title=Megafauna extinction in South America: A new chronology for the Argentine Pampas |url=https://www.sciencedirect.com/science/article/pii/S0031018215000899 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=425 |pages=41–49 |doi=10.1016/j.palaeo.2015.02.026 |bibcode=2015PPP...425...41P |issn=0031-0182}}</ref><ref name="Cuadrelli-2018" /> Temperatures in this region were lower than the present, with an estimated [[Temperature|mean annual temperature]] {{Convert|4.2|C|F}} in the Pampas compared to {{Convert|16.4|C|F}} in Buenos Aires today. The Pampas specifically was a mix of semi-arid Patagonian and tropical Brazilian climates during the middle Pleistocene before the expansion of the drier climates.<ref name=":4">{{Cite journal |last1=Prado |first1=José Luis |last2=Alberdi |first2=María Teresa |last3=Bellinzoni |first3=Jonathan |date=2021 |title=Pleistocene Mammals from Pampean Region (Argentina). Biostratigraphic, Biogeographic, and Environmental Implications |journal=Quaternary |language=en |volume=4 |issue=2 |pages=15 |doi=10.3390/quat4020015 |issn=2571-550X |doi-access=free }}</ref> This is in stark contrast to the [[Bermejo Formation]] of [[Formosa Province]], Argentina where the climate and fauna suggest a more arid environment with fewer grasslands.<ref>Kruck, W., Helms, F., Geyh, M. A., Suriano, J. M., Marengo, H. G., & Pereyra, F. (2011). Late pleistocene-holocene history of chaco-pampa sediments in Argentina and Paraguay. ''E&G Quaternary Science Journal'', ''60''(1), 14.</ref><ref>Zurita, A. E., M. Taglioretti, M. De los Reyes, C. Oliva, and F. Scaglia. 2014. First Neogene skulls of Doedicurinae (Xenarthra, Glyptodontidae): morphology and phylogenetic implications. Historical Biology 28:423–432.</ref> ''G. jatunkhirkhi'' specifically is known only from Andean climate of Eastern Cordillera in Bolivia, causing it to evolve to be smaller in size than lowland species due to less support for larger masses.<ref name="Cuadrelli-2020" /><ref name="Zurita-2017" /> ''G. jatunkhirkhi'' is not the only example of this in Xenarthra, with species of ''Panochthus'' and ''Pleurolestodon'' evolving to be smaller in size in mountainous regions.<ref name="Zurita-2017" /><ref name="Cuadrelli-2020" />
[[File:SerraGeralI.jpg|left|thumb|240x240px|The [[Pampas]], where ''Glyptodon'' was a grazer|alt=The Pampas grasslands.]]
During the Ensenadan and Marplatan, ''Glyptodon'' coexisted with a variety of mammals unique to the period such as the [[Notoungulata|notoungulate]] ''[[Mesotherium]]'', canid ''[[Theriodictis]],'' and a species of the giant bear ''[[Arctotherium
Material previously assigned to ''Glyptodon'' in northeast Brazil has been reassigned to ''Glyptotherium'', restricting the Brazilian distribution of ''Glyptodon'' to the southern provinces. However, two osteoderms with characteristics similar to those of ''Glyptodon'' have been found in [[Sergipe]] state in the northeast, suggesting that both genera occurred in this region during the Pleistocene.<ref name="Dantas2013">{{cite journal |last1=Dantas |first1=M. A. T. |last2=França |first2=L. M. |last3=Cozzuol |first3=M. A. |last4=Rincón |first4=A. D. |year=2013 |title=About the occurrence of ''Glyptodon'' sp. in the Brazilian intertropical region |journal=Quaternary International |volume=305 |pages=206–208 |bibcode=2013QuInt.305..206D |doi=10.1016/j.quaint.2011.06.024}}</ref> ''Glyptodon''<nowiki/>'s northernmost locality comes from Pleistocene deposits in central Colombia,<ref name="Zurita-2012" /> though many specimens formerly attributed to the genus come from the bordering country of [[Venezuela]].<ref name="Carlini-2022" />
=== Predation and relationship with humans ===
''Glyptodon'' coexisted with a variety of large predators including the cat ''Smilodon,'' [[jaguar]]s'','' and canid ''Protocyon''.<ref name="Bocherens-2016">{{Cite journal |last1=Bocherens |first1=Hervé |last2=Cotte |first2=Martin |last3=Bonini |first3=Ricardo |last4=Scian |first4=Daniel |last5=Straccia |first5=Pablo |last6=Soibelzon |first6=Leopoldo |last7=Prevosti |first7=Francisco J. |date=2016-05-01 |title=Paleobiology of sabretooth cat Smilodon populator in the Pampean Region (Buenos Aires Province, Argentina) around the Last Glacial Maximum: Insights from carbon and nitrogen stable isotopes in bone collagen |url=https://www.sciencedirect.com/science/article/pii/S0031018216000912 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=449 |pages=463–474 |doi=10.1016/j.palaeo.2016.02.017 |bibcode=2016PPP...449..463B |hdl=11336/43965 |issn=0031-0182}}</ref><ref>Montalvo, C. I., Zárate, M. A., Bargo, M. S., & Mehl, A. (2013). [https://www.researchgate.net/profile/M-Susana-Bargo/publication/259484888_Registro_Faunistico_y_Paleoambientes_del_Cuaternario_Tardio_Provincia_de_la_Pampa_Argentina/links/5433d9210cf2bf1f1f264a74/Registro-Faunistico-y-Paleoambientes-del-Cuaternario-Tardio-Provincia-de-la-Pampa-Argentina.pdf Registro faunístico y paleoambientes del Cuaternario tardío, provincia de La Pampa, Argentina.] ''Ameghiniana'', ''50''(6), 554-570.</ref> This belief is furthered by the discovery of fractured dorsal armor, which implies that ''Glyptodon'' had been in physical conflict with other animals.<ref name="Zurita2010" /> However, [[Isotope analysis|isotope analyses]] of the [[collagen]] from ''Glyptodon'' and other mammals of the Pampas region by Bocherens ''et al''. (2015) discovered little evidence to support the idea of predators feeding on ''Glyptodon''.<ref name="Bocherens-2016" /> Instead, it was found that ''Glyptodon'' as well as herbivorous mammals living in denser forests made up a smaller portion of carnivore diets, whereas open grazers such as ''Lestodon'' and ''Macrauchenia'' were consumed more often''.''<ref name="Bocherens-2016" /> Furthermore, the appearance of secondary armor in the dermis of ''Glyptodon'' coincides with the arrival of North American predators in South America during the [[Great American Interchange]].<ref name=":0" /> For this reason, it was hypothesized that the osteoderms developed as a defensive/offensive mechanism to combat the new arrivals of the area.<ref name="Zurita2010" />
''Smilodon'' may have occasionally preyed upon glyptodontines, based on a skull of ''Glyptotherium texanum'' which bears the distinctive elliptical puncture marks that best match those of the [[machairodont]] cat, indicating that the predator successfully bit into the skull through the armored cephalic shield.<ref>{{cite book |last=Antón |first=Mauricio |title=Sabertooth |date=2013 |publisher=University of Indiana Press |isbn=978-0-253-01042-1 |location=Bloomington, Indiana |pages=203–204}}</ref> The ''Glyptotherium'' in question was a juvenile, with a still-developing head shield, making it far more vulnerable to the cat's attack.<ref name="Gillette2">{{cite journal |last=Gillette |first=D. D. |date=Spring 2010 |title=Glyptodonts in Arizona |url=http://azgeology.azgs.arizona.edu/archived_issues/azgs.az.gov/arizona_geology/spring10/article_feature.html |journal=Arizona Geology |publisher=[[Arizona Geological Survey]] |access-date=2018-08-17}}</ref> Although originally theorized by George Brandes to be possible in 1900,<ref name=":25">Brandes, G. (1900) : Ueber eine Ursache des Aussterbens Diluvialer Säugethiere. Corrblatt d. Deutsch . ''Ges. f. Anthropol. Jahrg. 31. Munichen'' 1901.</ref> ''Smilodon'' canines could not pierce the thick carapace osteoderms of glyptodontines.<ref name=":26">Bohlin, B. (1940). 8. Food habit of the machairodonts, with special regard to ''Smilodon''.</ref> Brandes imagined that the evolution of thick glyptodontine armor and long machairodont canines was an example of [[coevolution]],<ref name=":25" /> but Birger Bohlin argued in 1940 that the teeth were far too fragile to do damage against glyptodontine armor.<ref name=":26" /><ref name="Zurita2010" /> [[File:Glyptodon old drawing.jpg|thumb|Humans hunting ''Glyptodon'', by [[Heinrich Harder]]|alt=Humans hunting Glyptodon.|236x236px]]
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== Extinction ==
{{Main|Late Pleistocene extinctions}}
Some evidence suggests that humans drove glyptodontines to extinction.<ref name = "islands&continents">{{Cite book▼
''Glyptodon'', along with all other glyptodonts became extinct around the end of the Late Pleistocene, as part of [[Late Pleistocene extinctions|a wave of extinctions of most large mammals]] across the Americas.
▲Some evidence suggests that humans drove glyptodontines to extinction.<ref name
| last1 = Martin | first1 = P. S. | author-link = Paul Schultz Martin
| last2 = Steadman | first2 = D. W. | author2-link = David Steadman
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}}</ref> Evidence from the Campo Laborde and La Moderna archaeological sites in the Argentine Pampas suggest that ''Glyptodon'<nowiki/>''s relatives ''Doedicurus'' and ''Panochthus'' survived until the Early Holocene, coexisting with humans for a minimum of 4,000 years.<ref name="Politis2008">{{cite journal|last1=Politis|first1=G. G.|last2=Messineo|first2=P. G.|title=The Campo Laborde site: New evidence for the Holocene survival of Pleistocene megafauna in the Argentine Pampas|journal=Quaternary International|volume=191|issue=1|date= November 2008 |pages=98–114 |doi=10.1016/j.quaint.2007.12.003|bibcode=2008QuInt.191...98P }}</ref> This overlap provides support for models showing that the South American Pleistocene extinctions resulted from a combination of climatic change and anthropogenic causes.<ref name="Politis2008" /> These sites have been interpreted as ones used for butchering megafauna (''Megatherium'' and ''Doedicurus''); however, some of the chronology has been problematic and controversial, due to poor preservation of the collagen used for dating.<ref name="Politis2008" /> The extinction rates in South America during the late Pleistocene were the highest out of any continent, with all endemic animals weighing over {{Convert|100|kg|lb}} going extinct by the middle Holocene.<ref name="Fariña2013" /> This supports the idea of human hunting as a drive for the extinction of ''Glyptodon,'' as the arrival of humans around 16,000 years BP to such a formerly isolated continent may have caused extinction rates to become higher.<ref name=":5">{{Cite journal |last1=Prates |first1=Luciano |last2=Perez |first2=S. Ivan |date=2021-04-12 |title=Late Pleistocene South American megafaunal extinctions associated with rise of Fishtail points and human population |journal=Nature Communications |language=en |volume=12 |issue=1 |pages=2175 |doi=10.1038/s41467-021-22506-4 |issn=2041-1723 |pmc=8041891 |pmid=33846353|bibcode=2021NatCo..12.2175P }}</ref><ref name="Fariña2013" /><ref>{{Cite journal |last1=Prates |first1=Luciano |last2=Politis |first2=Gustavo G. |last3=Perez |first3=S. Ivan |date=2020-07-22 |title=Rapid radiation of humans in South America after the last glacial maximum: A radiocarbon-based study |journal=PLOS ONE |language=en |volume=15 |issue=7 |pages=e0236023 |doi=10.1371/journal.pone.0236023 |issn=1932-6203 |pmc=7375534 |pmid=32697794 |bibcode=2020PLoSO..1536023P |doi-access=free }}</ref>
The extinction of ''Glyptodon'' notably coincides with the end of the [[Antarctic Cold Reversal]] period in which, for 1,700 years, temperatures dropped before spiking after ending at 12.7 ka.<ref>{{Cite journal |last1=Orombelli |first1=Giuseppe |last2=Maggi |first2=Valter |last3=Delmonte |first3=Barbara |date=2010-06-01 |title=Quaternary stratigraphy and ice cores |url=https://www.sciencedirect.com/science/article/pii/S1040618209003474 |journal=Quaternary International |series=Plio-Pleistocene Correlation and Global Change |language=en |volume=219 |issue=1 |pages=55–65 |doi=10.1016/j.quaint.2009.09.029 |bibcode=2010QuInt.219...55O |issn=1040-6182}}</ref><ref>{{Cite journal |last1=Weber |first1=M. E. |last2=Clark |first2=P. U. |last3=Kuhn |first3=G. |last4=Timmermann |first4=A. |last5=Sprenk |first5=D. |last6=Gladstone |first6=R. |last7=Zhang |first7=X. |last8=Lohmann |first8=G. |last9=Menviel |first9=L. |last10=Chikamoto |first10=M. O. |last11=Friedrich |first11=T. |last12=Ohlwein |first12=C. |date=2014 |title=Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation |url=https://www.nature.com/articles/nature13397 |journal=Nature |language=en |volume=510 |issue=7503 |pages=134–138 |doi=10.1038/nature13397 |pmid=24870232 |bibcode=2014Natur.510..134W |s2cid=205238911 |issn=1476-4687}}</ref> Many climatic fluctuations occurred during the late Pleistocene between humid and dry cycles, with ''Glyptodon'' preferring drier climates. Following the Antarctic Cold Reversal, temperatures rose and the climate became more consistently humid, which then led C3 grasses to become increasingly replaced by C4 grasses and southern beech trees. These changes led vulnerable, grazing-specialized forms like glyptodontines, toxodonts, and some ground sloths to become extinct.<ref>{{Cite journal |last1=Villavicencio |first1=Natalia A. |last2=Werdelin |first2=Lars |date=2018-09-01 |title=The Casa del Diablo cave (Puno, Peru) and the late Pleistocene demise of megafauna in the Andean Altiplano |url=https://www.sciencedirect.com/science/article/pii/S0277379118301318 |journal=Quaternary Science Reviews |language=en |volume=195 |pages=21–31 |doi=10.1016/j.quascirev.2018.07.013 |bibcode=2018QSRv..195...21V |s2cid=134626837 |issn=0277-3791}}</ref><ref>{{Cite journal |last1=Hubbe |first1=Alex |last2=Hubbe |first2=Mark |last3=Karmann |first3=Ivo |last4=Cruz |first4=Francisco W. |last5=Neves |first5=Walter A. |date=2011 |title=Insights into Holocene megafauna survival and extinction in southeastern Brazil from new AMS 14C dates |url=https://www.cambridge.org/core/journals/quaternary-research/article/abs/insights-into-holocene-megafauna-survival-and-extinction-in-southeastern-brazil-from-new-ams-14c-dates/38AB0ACF3EE6A9405937A0E22A613F8F |journal=Quaternary Research |language=en |volume=79 |issue=2 |pages=152–157 |doi=10.1016/j.yqres.2012.11.009 |s2cid=129827927 |issn=0033-5894}}</ref> Around 11.5 ka, temperatures peaked before again dropping, resulting in the extinction of several different genera of mammals including some megafauna. ''Glyptodon'' along with genera such as ''Glossotherium'' and ''Morenelaphus'' were wiped out, though several other groups lived for several thousand years after.<ref name="Mitchell-2016" /><ref name="Ubilla-2018" />
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[[Category:Prehistoric placental genera]]
[[Category:Pleistocene xenarthrans]]
[[Category:Pleistocene mammals of South America]]
[[Category:Pleistocene Argentina]]
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