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{{Short description|An extinct genus of mammals belonging to the armadillo order of xenarthrans}}
{{distinguish|text=the closely related [[Glyptodon]]}}
{{good article}}
{{Automatic taxobox
| fossil_range = [[Pliocene|Early Pliocene]]-[[Late Pleistocene]] ([[Blancan]]-[[Rancholabrean]]) ([[Ensenadan]]-[[Lujanian]])<br />~{{fossil range|3.6|0.015}}
| image = Glyptotherium Holotype NMNH.jpg
| image_caption = ''G. texanum'' holotype ([[USNM]] 10536), [[National Museum of Natural History]]
| taxon = Glyptotherium
| authority = Osborn, 1903
| type_species = {{extinct}}'''''Glyptotherium texanum'''''
| type_species_authority = Osborn, 1903
| subdivision_ranks = Other [[Species]]
| subdivision = * {{extinct}} ''G. cylindricum'' (Brown, 1912)
| range_map = Glyptodon and Glyptotherium Distribution Map2.jpg
| range_map_caption = Distribution of ''Glyptotherium'' (orange) compared to ''Glyptodon'''s (green).
| synonyms = * ''Boreostracon'' Simpson, 1929
* ''Brachyostracon'' Brown, 1912
* ''Xenoglyptodon'' Meade, 1953
{{collapsible list|bullets = true
 |title=<small>Synonyms of ''G. texanum''</small>
|''Glyptotherium arizonae'' <small>Gidley, 1926</small>
|''Xenoglyptodon fredericensis'' <small>Meade, 1953</small>
|''Glyptodon fredericensis'' <small>(Meade, 1953)</small>
}}
{{collapsible list|bullets = true
 |title=<small>Synonyms of ''G. cylindricum''</small>
|''Glyptodon mexicanum'' <small>Cuatáparo and Ramírez, 1875</small>
|''Glyptodon nathorsti'' <small>Felix and Lenk, 1875</small>
|''Glyptodon petaliferus'' <small>Cope, 1888</small>
|''Brachyostracon cylindricum'' <small>Brown, 1912</small>
|''Brachyostracon mexicanum'' <small>(Cuatáparo and Ramírez, 1875)</small>
|''Glyptodon rivipacis'' <small>Hay, 1923</small>
|''Boreostracon floridanus'' <small>Simpson, 1929</small>
|''Glyptotherium floridanum'' <small>Simpson, 1929</small>
|''Glyptotherium mexicanum'' <small>(Cuatáparo and Ramírez, 1875)</small>
}}
}}

'''''Glyptotherium''''' (from [[Greek language|Greek]] for 'grooved or carved beast') is a genus of [[glyptodont]] (an extinct group of large, herbivorous [[armadillo]]s) in the family [[Chlamyphoridae]] (a family of South American armadillos) that lived from the [[Zanclean|Early Pliocene]], about 3.6 million years ago, to the Late Pleistocene, around 15,000 years ago. It had a wide distribution, living in the [[United States]], [[Mexico]], [[Guatemala]], [[Costa Rica]], [[Honduras]], [[El Salvador]], [[Panama]], [[Venezuela]], and [[Brazil]]. The genus was first described in 1903 by American [[Paleontology|paleontologist]] [[Henry Fairfield Osborn]] with the [[type species]] being, '''''G. texanum''''', based on fossils that had been found in the Pliocene [[Mount Blanco|Blancan Beds]] in [[Llano Estacado]], [[Texas]], USA. ''Glyptotherium'' fossils have since been unearthed from many more fossil sites, from Florida to Colombia. Another species, '''''G. cylindricum''''', was named in 1912 by fossil hunter [[Barnum Brown]] on the basis of a partial skeleton that had been unearthed from the [[Pleistocene]] deposits in [[Jalisco|Jalisco, Mexico]]. The two species differ in several aspects, including age, with ''G. texanum'' being from the older Early Pliocene to [[Early Pleistocene]] strata, whereas ''G. cylindricum'' is exclusive to the [[Late Pleistocene]].

''Glyptotherium'' was a large, quadrupedal (four-legged), [[Herbivore|herbivorous]] armadillo with an armored [[carapace]] (top shell) that was made of hundreds of interconnected [[osteoderm]]s (structures in dermis composed of bone). Other pieces of armor covered the tail and [[Skull roof|cranium roof]], the skull being tall with [[hypsodont]] (high-crowned) teeth. As for the postcranial anatomy, [[Pelvis|pelves]] fused to the carapace, an amalgamate vertebral column, short limbs, and small digits are characteristic of ''Glyptotherium'' and its relatives. ''Glyptotherium'' reached up to 2 meters (6.56 feet) long and 400 kilograms (880 pounds) in weight, making it one of the largest glyptodonts but not as large as its close relative ''Glyptodon'' or ''[[Doedicurus]],'' the largest known glyptodont. ''Glyptotherium'' is morphologically and [[Phylogenetics|phylogenetically]] most similar to ''Glyptodon,'' however they differ in several ways. ''Glyptotherium'' is smaller on average, with a shorter carapace, a relatively longer tail, and a slender [[zygoma]], or cheek bone.

Glyptodonts evolved first during the [[Eocene]], but greatly diversified in the [[Miocene]] and [[Pliocene]], largely in the [[Santacrucian]] sites of [[Argentina]]. However, their diversity diminished into the Pleistocene, though they peaked in size during this period. ''Glyptotherium'' is considered an example of North American [[megafauna]], of which most have become extinct, and may have been wiped out by changing climate or human interference. ''Glyptotherium'' was primarily a [[Grazing|grazer]], but also had a mixed diet of fruits and other plants, that lived on open grasslands. The armor could protect the animal from predators, of which many coexisted with ''Glyptotherium'' during its existence, including the "saber-tooth cat" ''[[Smilodon]]'', the "bone-crushing dog" ''[[Borophagus]]'', and the "short-faced bears" ([[Tremarctinae]]).

== History and phylogeny ==
Fossils attributable to ''Glyptotherium'' have been found as early as the 1870s, when civil engineers J. N. Cuatáparo and Santiago Ramírez collected a skull, nearly complete [[carapace]], and associated postcranial skeleton of a glyptodont from a drainage canal near [[Tequixquiac]], [[Mexico]], the fossils coming from the [[Rancholabrean|Rancholabrean age]] of the [[Pleistocene]].<ref name=":02">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=":110">{{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 |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|hdl-access=free }}</ref>{{Sfn|Gillette|Ray|1981|p=3|loc=}} This was the first discovery of a glyptodont in North America.<ref name=":110" />{{Sfn|Gillette|Ray|1981|p=3|loc=}} Cuatáparo and Ramírez named the fossils ''Glyptodon mexicanum'' in 1875, but the fossils have been lost''.''<ref name=":02" />{{Sfn|Gillette|Ray|1981|p=16}} Another species of ''Glyptodon'' from Mexico was described in 1889, ''G. nathoristi,'' by German paleontologists based on carapace remains from Pleistocene localities in [[Ejutla District|Ejutla]], [[Oaxaca]].<ref>Felix, J. P. (1899). ''Beiträge zur geologie und paläontologie der republik Mexico'' (Vol. 1). A. Felix.</ref><ref>Maldonado, M. (1948). Los vertebrados fósiles del Cuaternario en México. ''Revista de la Sociedad Mexicana de Historia Natural, 9'' (1-2): 1-35</ref> Both of these species have since been synonymized with ''G. cylindricum.<ref name=":110" />''{{Sfn|Gillette|Ray|1981|p=3}}

The first ''Glyptotherium'' fossils to be described from the United States were described in 1888 by paleontologist [[Edward Drinker Cope]] and consisted only of a single carapace osteoderm that had been collected from the [[Early Pleistocene|Lower Pleistocene]] "''[[Equus (genus)|Equus]]'' Beds" of [[Nueces County, Texas|Nueces County]], [[Texas]].<ref name=":62">{{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><ref name=":110" /> Cope named his osteoderm ''[[Glyptodon]] peltaliferus'',<ref>Cope, E. D. (1889). the edentata of North America. ''The American Naturalist'', ''23''(272), 657-664.</ref> but Cope did not give the species a proper description that followed [[International Code of Zoological Nomenclature|ICZN]] rules, making it a ''[[nomen nudum]]'' and it has since been synonymized with ''G. cylindricum''.<ref name=":110" />{{Sfn|Gillette|Ray|1981|p=3}} The next year, [[Joseph Leidy]] named ''Glyptodon floridanus'' based on isolated carapace osteoderms and pieces of caudal armor, though some were also referred to ''G. peltaliferus'',<ref>Leidy, J. (1889). Description of vertebrate remains from Peace Creek, Florida. ''Transactions of the Wagner Free Institute of Science of Philadelphia'', ''2'', 19-31.</ref> that were collected from [[Pleistocene]] deposits in [[DeSoto County, Florida|DeSoto County]], [[Florida]].{{Sfn|Gillette|Ray|1981|p=6}}<ref>Leidy, D. (1889). Fossil vertebrates from Florida. ''Proceedings of the Academy of Natural Sciences of Philadelphia'', 96-97.</ref> This species is now seen as a ''[[Glossary of scientific naming|nomen vanum]]'' and considered a junior synonym of ''Glyptotherium cylindricum'' by a review of the genus by American paleontologists [[David Gillette]] and Clayton Ray (1981).{{Sfn|Gillette|Ray|1981|p=14}}<ref name=":110" />
[[File:Compte-rendu_des_séances_du_sixième_Congrès_international_de_zoologie,_tenu_à_Berne_du_14_au_19_août_1904_(1905)_(20485352308).jpg|alt=The holotype of G. texanum next to a skeleton of the Southern naked-tailed armadillo.|left|thumb|The holotype of ''G. texanum'' next to a skeleton of the [[Southern naked-tailed armadillo]].]]
''Glyptotherium'' itself was named in 1903 when fossils collected by an [[American Museum of Natural History]] expedition led by J. W. Gidley to the [[Pliocene|Early Pliocene]] strata from the [[Blanco Formation]] of [[Llano Estacado]], Texas were described by [[Henry Fairfield Osborn]] as a new genus and species of glyptodont, ''Glyptotherium texanum''.<ref name=":62" /> The fossils were deposited at the AMNH and consist of a carapace and associated postcranial elements, one of the few ''G. texanum'' skeletons known.<ref name=":62" /><ref name=":110" /> The generic name ''Glyptotherium'' comes from the Greek roots ''glyph'' meaning "carved" or "grooved", after its relative ''[[Glyptodon]],'' and ''therion'' meaning "beast", a commonly used suffix for prehistoric mammals. The species name of the type species, ''G. texanum,'' is after the holotype's discovery in Texas.<ref name=":62" />

Another find came in 1910 when, while traveling in [[Jalisco]], Mexico, fossil hunter [[Barnum Brown]] collected a complete dorsal carapace and several additional fossils, including teeth, of a single individual from the Pleistocene strata of the area.{{Sfn|Gillette|Ray|1981|p=3}}<ref name=":72">{{Cite journal |last=Brown |first=Barnum |date=1912 |title=Brachyostracon, a new genus of glyptodonts from Mexico. |url=https://digitallibrary.amnh.org/handle/2246/1402 |journal=Bulletin of the AMNH |language=en-US |volume=31 |issue=17 |pages=167–190 |hdl=2246/1402}}</ref> The specimen was sent to the American Museum of Natural History as well, where it was described by Brown in 1912 as a new genus and species of glyptodont, ''Brachyostracon cylindricum''.<ref name=":72" /> The species name ''cylindricum'' meaning "cylindrical" is after the cylindroid anatomy of the premolars in the holotype of ''G. cylindricum.''<ref name=":72" /> Brown also recombined ''Glyptodon mexicanum'' into ''Brachyostracon mexicanum.''<ref name=":72" /> ''Brachyostracon'' is now seen synonymous with ''Glyptotherium'' on the genus level, but ''G. cylindricum'' is a valid species.<ref name=":110" /><ref name=":210">{{citation |last1=Gillette |first1=D. D. |title=Glyptodonts of North America |date=1981 |url=https://repository.si.edu/bitstream/handle/10088/1966/SCtP-0040-Lo_res.pdf?sequence=2&isAllowed=y |last2=Ray |first2=C. E.}}</ref> In 1923, [[Oliver Perry Hay]] named a new species of ''Glyptodon'', ''G. rivipacis'', based on the fossils described by Leidy from [[DeSoto County, Florida|DeSoto County]], Florida.<ref>Hay, O. P. (1923). ''The Pleistocene of North America and Its Vertebrated Animals from the States East of the Mississippi River and from the Canadian Provinces East of Longitude 95> O'' (No. 22). Carnegie institution of Washington.</ref> This species is now seen as a ''[[nomen nudum]]'' and synonymous with ''Glyptotherium cylindricum''.<ref name=":110" />{{Sfn|Gillette|Ray|1981|p=6 & 14}} Hay also described well preserved fossils, including skull elements and teeth, that were collected from Rancholabrean strata in [[Wolfe City, Texas|Wolf City]] and [[Sinton, Texas]] that were referred to Cope's ''Glyptodon peltaliferus''.<ref name=":210" /> These fossils have since been referred to ''G. cylindricum.<ref name=":110" />''<ref name=":210" />

A third genus of North American glyptodont, ''Boreostracon floridanum'', was established by [[George Gaylord Simpson]] in 1929 based on several isolated specimens unearthed by the AMNH from Rancholabrean age localities in Florida, the holotype specimen being the rear portion of a carapace recovered from Seminole Field locality in [[Pinellas County, Florida|Pinellas County]], Florida.{{Sfn|Gillette|Ray|1981|p=14}}<ref name=":102">Simpson, G. G., & Holmes, W. W. (1929). [https://digitallibrary.amnh.org/handle/2246/1326 Pleistocene mammalian fauna of the Seminole Field, Pinellas County, Florida]. Bulletin of the AMNH; v. 56, article 8.</ref> Simpson referred all of the fossils previously described from Florida to ''B. floridanum'' and believed that all of the glyptodont fossils unearthed from North America were not of ''Glyptodon''.<ref name=":102" /> However, Simpson chose not to designate a new genus or species for ''Glyptodon peltaliferus'', but he still believed that they were from a separate form of glyptodont.<ref name=":102" /> ''Boreostracon floridanum'' has been synonymized with ''Glyptotherium cylindricum.''<ref name=":110" />

Research into North American glyptodonts diminished after the research of Gidley, Hay, Simpson, and others, but some paleontologists still incorrectly referred fossils from the continent to ''Glyptodon''.<ref name=":210" />

In 1927, many [[Early Pleistocene]] age fossils were collected by the [[University of Oklahoma]] from a locality in [[Frederick, Oklahoma]], including several fragmentary fossils of glyptodonts, [[Equidae|equids]], [[gomphothere]]s, and [[Titanotylopus|camelids]].<ref name=":202">Meade, G. E. (1953). [https://www.jstor.org/stable/pdf/30079696.pdf An early Pleistocene vertebrate fauna from Frederick, Oklahoma.] ''The Journal of Geology'', ''61''(5), 452-460.</ref> The glyptodont fossils were originally referred to ''Glyptodon'' in 1928,<ref>Gould, C. N. (1928). The fossil ''Glyptodon'' in the Frederick gravel beds. In ''Proceedings of the Oklahoma Academy of Science'' (pp. 148-150).</ref><ref>{{Cite journal |last=Spier |first=Leslie |date=1928-02-10 |title=Concerning Man's Antiquity at Frederick, Oklahoma |url=https://www.science.org/doi/10.1126/science.67.1728.160 |journal=Science |language=en |volume=67 |issue=1728 |pages=160–161 |bibcode=1928Sci....67..160S |doi=10.1126/science.67.1728.160 |issn=0036-8075 |pmid=17752885}}</ref> but were not properly described until 1953.<ref name=":202" /> They were described as a new genus and species, ''Xenoglyptodon fredericensis'', in 1953 on the basis of a partial lower jaw and several teeth.<ref name=":202" /> The species is now considered a junior synonym of ''Glyptotherium texanum''.<ref name=":110" /><ref name=":210" /> After all of these genera were named, a great reassessment was not conducted until 1981, David Gillette and Clayton Ray published a monograph on North American glyptodonts. In their monograph, they recombined all previously named genera and species into ''Glyptotherium,'' synonymized some species, and also researched the genus' ecology, anatomy, and distribution.<ref name=":210" /> However, ''G. arizonae, G. floridanum,'' and ''G. mexicanum'' were kept as valid species,<ref name=":210" /> all of which were later synonymized with ''G. texanum'' and ''G. cylindricum'' after the discovery of more complete skeletons that proved their synonymy.<ref name=":110" /><ref name=":142">{{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 |url=https://doi.org/10.1007/s10914-015-9309-6 |journal=Journal of Mammalian Evolution |language=en |volume=23 |issue=2 |pages=133–154 |doi=10.1007/s10914-015-9309-6 |issn=1573-7055 |s2cid=15219339}}</ref> After later review, the former species was declared a junior synonym of ''G. texanum''<ref name=":110" /><ref name=":142" /> and the latter two synonyms of ''G. cylindricum''.<ref name=":110" />

From the 2000s to the 2020s, hundreds of additional fossils were referred to the genus from Central America and Brazil.<ref name=":52">Oliveira, É. V., Porpino, K. D., & Baretto, A. (2010). [https://www.academia.edu/download/46178702/On_the_presence_of_Glyptotherium_in_the_20160602-16842-gw2dkg.pdf On the presence of ''Glyptotherium'' in the Late Pleistocene of Northeastern Brazil, and the status of "''Glyptodon''" and "''Chlamydotherium''". Paleobiogeographic implications.]{{Dead link|date=August 2024 |bot=InternetArchiveBot |fix-attempted=yes }} ''Neues Jahrbuch fur Geologie und Palaontologie-Abhandlungen'', ''258''(3), 353.</ref><ref name=":132">{{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 |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 |bibcode=2021JSAES.11203576L |doi=10.1016/j.jsames.2021.103576 |issn=0895-9811 |s2cid=244181217}}</ref> These include fossils previously referred to ''[[Glyptodon]]'' and ''[[Hoplophorus]]'', as many fossils were hastily assigned to both by 19th century paleontologists.<ref name=":52" /><ref name=":34" /> One of the specimens reassigned to ''Glyptotherium'', an isolated dorsal carapace osteoderm, was collected from Pleistocene age carbonate caves in [[Lagoa Santa, Goiás|Lagoa Santa]], [[Minas Gerais]], Brazil by Friedrich von Sellow during the early 1800s.<ref name=":52" /> It was later described as a new species of ''Hoplophorus'', ''H. meyeri'', in 1845 by Danish paleontologist [[Peter Wilhelm Lund]].<ref>Lund, P. W. (1845): Conspectum-dasypodum. – Det Kongelige Dans- ke Videnskabernes Selskbas Naturvidenskabelige og Mathematiske Afhandlinger, 11: lxxxii-lxxxvi.</ref><ref name=":34" /><ref name=":52" /> Lund incorrectly named the taxon however, making it a ''nomen nudum''.<ref name=":52" /> The osteoderm was referred to ''Glyptotherium'' in 2010, making it the first known ''Glyptotherium'' specimen.<ref name=":52" /> In 2022, a host of fossils of ''Glyptotherium cylindricum'' including skulls, some preserving pathologies caused by humans, were described that had been collected from several sites in [[Falcón]], northern Venezuela that dated to the Late Pleistocene.<ref name=":42">{{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 |issn=1664-2384 |s2cid=249681104 |doi-access=free|bibcode=2022SwJP..141...11C }}</ref>
[[File:BarnumBrown_Student.jpg|alt=Barnum Brown's portrait|thumb|A portrait of [[Barnum Brown]], discoverer of ''G. cylindricum'']]

=== Phylogeny ===
''Glyptotherium'' is a genus in the subfamily Glyptodontinae, an extinct clade of large, thoroughly armored armadillos that first evolved in the [[Eocene|Late Eocene]] (ca. 33.5 mya) and went extinct in the [[Late Pleistocene extinctions|Late Pleistocene-Early Holocene extinctions]].<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 |hdl=11336/48521 |hdl-access=free }}</ref> 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]]'' (a large, mace-clubbed glyptodont) specimen, and a nearly complete [[mitochondrial genome]] was reconstructed (76x [[Coverage (genetics)|coverage]]). Comparisons with the DNA of modern armadillos revealed that glyptodonts diverged from [[Tolypeutinae|tolypeutine]] and [[Chlamyphorinae|chlamyphorine]] armadillos approximately 33.5 million years ago in the [[Priabonian|late Eocene]].<ref name="Mitchell2016" /><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 |hdl=11336/49579 |hdl-access=free }}</ref> This prompted moving them from their own family, Glyptodontidae, within the [[Extant taxon|extant]] [[Chlamyphoridae]] as a subfamily, renamed Glyptodontinae.<ref name="Delsuc20162" /> Following this genetic data and the fossil record, glyptodonts rapidly evolved their characteristic anatomy and enormous sizes (also known as gigantism), possibly due to the cooling of temperatures, dryer climates, expansion of savannahs, and the size of carnivores like ''[[Arctotherium]]'' and ''[[Smilodon]].''<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 sloth]]s) 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="Delsuc2016">{{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.|title= The phylogenetic affinities of the extinct glyptodonts|journal= Current Biology|volume= 26|issue= 4|date= 2016-02-22|pages= R155–R156|doi= 10.1016/j.cub.2016.01.039|pmid= 26906483|url= https://hal.archives-ouvertes.fr/hal-01879335/file/Delsuc_Poinar_CB_Correspondence_Manuscript_with_SuppInfo_rev1.pdf|doi-access= free|bibcode= 2016CBio...26.R155D}}</ref>
{{clade|{{clade
  |1=[[Dasypodidae]]
  |label2=&nbsp;[[Chlamyphoridae]]&nbsp;
  |2={{clade
    |label1=&nbsp;[[Euphractinae]]&nbsp;
    |1={{clade
      |1=''[[Euphractus]]''
      |2={{clade
        |1= ''[[Zaedyus]]''
        |2={{clade
          |1= ''[[Chaetophractus villosus]]''
          |2={{clade
              |1=''[[Chaetophractus nationi]]''
              |2=''[[Chaetophractus vellerosus|C. vellerosus]]''
             }}
           }}
         }}
       }}
    |2={{clade
      |label1=
      |1= †'''Glyptodontinae''' (''[[Doedicurus]]'')
      |2={{clade
        |label1=&nbsp;[[Chlamyphorinae]]&nbsp;
        |1={{clade
            |1=''[[Chlamyphorus]]''
            |2=''[[Calyptophractus ]]''
             }}
        |label2=[[Tolypeutinae]]
        |2={{clade
          |1=''[[Priodontes]]''
          |2={{clade
            |1=''[[Tolypeutes]]''
            |2=''[[Cabassous]]''
             }}
           }}
         }}
       }}
     }}
   }}|style=font-size:90%;line-height:100%;|label1=&nbsp;[[Cingulata]]&nbsp;}}
[[File:Pink_Fairy_Armadillo_(Chlamyphorus_truncatus)_(cropped).jpg|alt=A Pink Fairy Armadillo|left|thumb|The [[Pink fairy armadillo|Pink Fairy Armadillo]], an extant species of Chlamyphorid.]]
The internal phylogeny of Glyptodontinae is convoluted and in a flux, with many species and families erected on the basis of fragmentary or undiagnostic material that lacks comprehensive review.<ref name=":232">{{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 |url=https://doi.org/10.1080/02724634.2018.1525390 |journal=Journal of Vertebrate Paleontology |volume=38 |issue=5 |pages=e1525390 |bibcode=2018JVPal..38E5390C |doi=10.1080/02724634.2018.1525390 |issn=0272-4634 |s2cid=92335544}}</ref><ref name=":34">{{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 |url=https://doi.org/10.1080/02724631003765735 |journal=Journal of Vertebrate Paleontology |volume=30 |issue=3 |pages=911–927 |bibcode=2010JVPal..30..911P |doi=10.1080/02724631003765735 |issn=0272-4634 |s2cid=83888299 |hdl-access=free |hdl=11336/69074}}</ref><ref name=":110" /> It is usually considered its own family, but DNA analyses have reduced it to a subfamily with [[Tribe (biology)|tribes]] instead of subfamilies. One tribe, Glyptodontini (typically labeled Glyptodontinae) is a group of younger, larger glyptodonts that evolved in the [[Middle Miocene]] (ca. 13 mya) with ''[[Boreostemma]]'',<ref name=":182"/> but split into 2 genera, ''Glyptodon'' in the south and ''Glyptotherium'' in the north,<ref name=":110" /> though ''Glyptodon'' also lived in northern South America in [[Colombia]].<ref name=":110" /><ref name=":192">{{Cite journal |last1=Zurita |first1=Alfredo E. |last2=Miño-Boilini |first2=Ángel R. |last3=Francia |first3=Analía |last4=Arenas-Mosquera |first4=José E. |date=2012-12-31 |title=The Pleistocene Glyptodontidae Gray, 1869 (Xenarthra: Cingulata) of Colombia and some considerations about the South American Glyptodontinae |url=http://www.sbpbrasil.org/revista/edicoes/15_3/04_Zurita_et_al.pdf |journal=Revista Brasileira de Paleontologia |volume=15 |issue=3 |pages=273–280 |doi=10.4072/rbp.2012.3.04}}</ref> Glyptodontini is often recovered as more basal to most other glyptodonts like ''[[Doedicurus]], [[Hoplophorus]],'' and ''[[Panochthus]].'' Glyptodontini is distinguishable from other groups for example in that it has large, conical tubercular osteoderms absent or only present on the caudal (tailward) notch on the posterior end of the carapace and different ornamentation of the armor on the carapace than the tail.<ref name=":1332">{{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 |url=https://doi.org/10.1080/14772019.2020.1784300 |journal=Journal of Systematic Palaeontology |volume=18 |issue=18 |pages=1543–1566 |doi=10.1080/14772019.2020.1784300 |bibcode=2020JSPal..18.1543C |issn=1477-2019 |s2cid=221064742}}</ref> The sister taxon, or closest relative(s) of another taxon, to ''Glyptotherium'' is the genus ''Glyptodon'', which evolved in the Middle Pleistocene in Argentina.<ref name=":1332" /><ref name=":232" /> ''Glyptotherium'' is nearly identical to ''Glyptodon'' in many aspects, so much so that the first fossils of ''Glyptotherium'' to be described were misidentified as those of ''Glyptodon''.<ref name=":210" /><ref name=":02" />

When ''Glyptotherium'' was first described by [[Henry Fairfield Osborn]] in 1903, he placed it at the family level Glyptodontidae and although similar to ''Glyptodon'', Osborn stated that it was closer in appearance and classification to ''[[Panochthus]]'' and ''[[Neosclerocalyptus]]'' (then ''Sclerocalyptus'').<ref name=":62" /> [[Barnum Brown]] believed that his genus ''Brachyostracon'' and its 2 species, ''B. cylindricum'' and ''B. mexicanum'', were in their own family of glyptodonts based on the elongation of the skull of the latter species and the width of the carapace compared to its length.<ref name=":72" /> Brown did not coin any new name for this family however, and instead classified the genus within Sclerocalyptidae along with South American glyptodonts like ''[[Panochthus]]'', ''[[Neosclerocalyptus]]'', and ''[[Plohophorus]]''.<ref name=":72" /> [[George Gaylord Simpson]] classified his genus ''Boreostracon'' as a close relative of ''[[Glyptodon]]'', but still believed that there were multiple North American glyptodont genera.<ref name=":102" /> ''Xenoglyptodon'' was placed as a glyptodont close to the other North American genera by Meade (1953), but he did not state its relation to South American genera.<ref name=":202" /> 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=":1332" />
{{clade|{{clade
   |1=''[[Euphractus sexcinctus]]''
    |2={{clade
       |1=''[[Pampatherium]]''
       |label2=Glyptodontinae
       |2={{clade
          |1={{clade
             |label1=Glyptodontini
             |1={{clade
                |1={{clade
                   |1=''[[Boreostemma acostae]]''
                   |2=''[[Boreostemma venezolensis]]'' }}
                |2={{clade
                   |1={{clade
                      |1='''''Glyptotherium cylindricum'''''
                      |2='''''Glyptotherium texanum''''' }}
                   |2={{clade
                      |1=''[[Glyptodon|Glyptodon jatunkhirkhi]]''
                      |2={{clade
                         |1=''[[Glyptodon|Glyptodon reticulatus]]''
                         |2=''[[Glyptodon|Glyptodon munizi]]'' }} }} }} }}
          |2={{clade
             |1={{clade
                |1=''[[Propalaehoplophorus|Propalaehoplophorus australis]]''
                |2={{clade
                   |1=''[[Eucinepeltus|Eucinepeltus petestatus]]''
                   |2={{clade
                     |1=''[[Cochlops|Cochlops muricatus]]''
                     |2={{clade
                         |1=''[[Plohophorus|Plohophorus figuratus]]''
                         |2=''[[Pseudoplohophorus|Pseudoplohophorus absolutus]]''
                         |3={{clade
                         |label1=Doedicurini
                            |1={{clade
                               |1=''[[Eleutherocercus|Eleutherocercus antiquus]]''
                               |2=''[[Doedicurus clavicaudatus]]'' }}
                            |2={{clade
                            |label1=Neosclerocalyptini
                            |label2=Hoplophorini
                               |1={{clade
                                  |1=''[[Neosclerocalyptus|Neosclerocalyptus ornatus]]''
                                  |2=''[[Neosclerocalyptus|Neosclerocalyptus paskoensis]]'' }}
                              |2={{clade
                                  |1=''[[Hoplophorus|Hoplophorus euphractus]]''
                                  |2={{clade
                                     |1=''[[Panochthus|Panochthus intermedius]]''
                                     |2=''[[Panochthus tuberculatus]]''
                   }} }} }} }} }} }} }} }} }} }} }} }} }}|style=font-size:85%;line-height:80%|label1='''Chlamyphoridae'''}}

== Description ==
[[File:Glyptotherium_texanum_1910.jpg|alt=Life restoration|thumb|260x260px|A life restoration of ''G. texanum.'']]
Like its living relative, the armadillo, ''Glyptotherium'' had a shell that covered its entire torso, with smaller armor also covering the skull roof of the head, similar to a [[turtle]]. However, unlike the [[carapace]] (top shell) of a turtle, the ''Glyptotherium'' shell was made up of hundreds of small hexagonal scales, with ''Glyptotherium'' preserving up to 1800 [[osteoderm]]s (bony structures in dermis) or more in each individual.{{Sfn|Gillette|Ray|1981|p=2}} The axial skeleton of glyptodonts show extensive fusion in the vertebral column and the [[pelvis]] (hipbone) is fused to the carapace, making the pelvis entirely immobile.<ref name=":210" /> ''Glyptotherium'' was very graviportal and had short limbs that are very similar to those in other glyptodonts. The large tails of glyptodonts likely served as a counterbalance to the rest of the body and ''Glyptotherium''<nowiki/>'s caudal armor ended in a blunt tube that was composed of 2-3 fused tubes,<ref name=":110" /> in contrast to those of South American mace-tailed glyptodonts.{{Sfn|Gillette|Ray|1981|p=1}} 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=":210" /> During the Pleistocene, the glyptodonts diminished in phylogenetic diversity but increased in size.<ref name=":42" /><ref name=":110" /> ''Glyptotherium'' weights and sizes vary, but ''G. texanum'' was smaller and lighter than the later species, ''G. cylindricum.'' One specimen of ''G. cylindricum'' was estimated at 350-380 kilograms, compared to 457&nbsp;kg of its relative ''Glyptodon reticulatus.''<ref name=":42" /> The largest estimates of ''Glyptotherium''<nowiki/>'s mass are based on adult specimens from Brazil and Arizona, with one estimate of a ''G. cylindricum'' specimen placing it at {{Convert|710|kg|lb}} and a ''G. texanum'' individual at {{Convert|1,165|kg|lb}}.<ref name=":222">{{Cite bioRxiv |biorxiv=10.1101/482752 |first1=Mário André Trindade |last1=Dantas |first2=Alexander |last2=Cherkinsky |title=Integrative isotopic Paleoecology (δ13C, δ18O) of a Late Pleistocene vertebrate community from Sergipe, NE Brazil |date=2018-11-29 |language=en |last3=Lessa |first3=Carlos Micael Bonfim |last4=Santos |first4=Luciano Vilaboim |last5=Cozzuol |first5=Mario Alberto |last6=Omena |first6=Érica Cavalcante |last7=Silva |first7=Jorge Luiz Lopes da |last8=Sial |first8=Alcides Nóbrega |last9=Bocherens |first9=Hervé |pages=482752}}{{s2cid|91321429}}</ref> One specimen of ''G. cylindricum'', AMNH 15548, preserved a carapace length of 1690 centimeters compared to just 1400&nbsp;cm for MSM P4464, a ''G. texanum'' specimen.<ref name=":110" />
[[File:Glyptotherium cf. cylindricum skulls. Specimens from the Muaco (A, B) and Taima-Taima sites (C–I) are shown.webp|alt=Skulls of G. cylindricum from Venezuela.|left|thumb|Skulls of ''G. cylindricum'' from Venezuela.]]
''Glyptotherium texanum'' differs from ''G. cylindricum'' in the configuration of the external sculpturing of symmetrical, hexagonal osteoderms in the dorsal carapace. In the osteoderms of adult ''G. texanum,'' the central figures of the osteoderms are flat or weakly convex and very large, while those of ''G. cylindricum'' are flat or concave and much smaller.<ref name=":110" /><ref name=":82">{{Cite journal |last1=du Plessis |first1=Anton |last2=Broeckhoven |first2=Chris |last3=Yadroitsev |first3=Igor |last4=Yadroitsava |first4=Ina |last5=le Roux |first5=Stephan Gerhard |date=2018-06-01 |title=Analyzing nature's protective design: The glyptodont body armor |url=https://www.sciencedirect.com/science/article/pii/S1751616118301656 |journal=Journal of the Mechanical Behavior of Biomedical Materials |language=en |volume=82 |pages=218–223 |doi=10.1016/j.jmbbm.2018.03.037 |issn=1751-6161 |pmid=29621689 |s2cid=4608467}}</ref> In both species, the central figures of the osteoderms get larger towards the margins of the carapace.<ref name=":110" /><ref name=":142" /> Although ''G. texanum'' was believed to be larger than ''G. cylindricum'', the genus is believed to have been uniformly large throughout the Pliocene and Pleistocene.<ref name=":110" />

=== Skull and mandible ===
Glyptodont dentition has all [[hypsodont]] (high crowned teeth adapted for grazing) molariforms, cheek teeth, which are some of the most hypsodont known from terrestrial mammals.{{Sfn|Gillette|Ray|1981|p=200}} Glyptodont skulls have several unique features; the [[maxilla]] and [[Palate|palatine]] are enlarged vertically to make space for the molariforms, while the braincase is [[Brachycephaly|brachycephalic]], short and flat.{{Sfn|Gillette|Ray|1981|p=58}} Dermal armor was not restricted to the carapace and tail, as the [[skull roof]] was protected by a "cephalic shield" made of osteoderms.<ref name=":42" />{{Sfn|Gillette|Ray|1981|p=39}} Some paleontologists have proposed that ''Glyptotherium'' and some glyptodonts also had a proboscis or large snout similar to those in elephants and tapirs,{{Sfn|Gillette|Ray|1981|p=202}} but few have accepted this hypothesis.<ref name=":110" /><ref name=":42" /> Only one complete skull is known from ''Glyptotherium texanum'', while relatives like ''Glyptodon'' and ''Neosclerocalyptus'' are known from many skulls, giving a limited perspective on its anatomy.<ref>Zurita, A. E., Miño-Boilini, Á. R., Soibelzon, E., Carlini, A. A., & Paredes Rios, F. (2009). The diversity of Glyptodontidae (Xenarthra, Cingulata) in the Tarjia Valley (Bolivia): Systematic, biostratigraphic and paleobiogeographic aspects of a particular assemblage.(With 3 figures and 1 table). ''Neues Jahrbuch fur Geologie und Palaontologie-Abhandlungen'', ''251''(2), 225.</ref><ref>{{Cite journal |last1=Zurita |first1=A.E. |last2=Scarano |first2=A.C. |last3=Carlini |first3=A.A. |last4=Scillato-Yané |first4=G.J. |last5=Soibelzon |first5=E. |date=2011-04-04 |title=Neosclerocalyptus spp. (Cingulata: Glyptodontidae: Hoplophorini): cranial morphology and palaeoenvironments along the changing Quaternary |url=https://doi.org/10.1080/00222933.2010.536917 |journal=Journal of Natural History |volume=45 |issue=15–16 |pages=893–914 |doi=10.1080/00222933.2010.536917 |bibcode=2011JNatH..45..893Z |issn=0022-2933 |s2cid=85146482}}</ref> ''Glyptotherium''<nowiki/>'s [[Zygomatic bone|zygoma]] are narrow, slender, almost parallel, and close to the [[sagittal plane]] in frontal view; in ''Glyptodon'', this structure is broader, robust, divergent rather than parallel and more laterally placed. ''Glyptotherium'' and other glyptodonts preserve large nasal passages and sinuses that may have had nostrils adapted to breath in the cold arid climates of the Americas during the [[Pleistocene]].<ref>{{Cite journal |last1=Fernicola |first1=Juan Carlos |last2=Toledo |first2=Néstor |last3=Bargo |first3=M. Susana |last4=Vizcaíno |first4=Sergio F. |date=2012-09-22 |title=A neomorphic ossification of the nasal cartilages and the structure of paranasal sinus system of the glyptodont Neosclerocalyptus Paula Couto 1957 (Mammalia, Xenarthra) |url=https://palaeo-electronica.org/content/2012-issue-3-articles/305-glyptodont-nasal-anatomy |journal=Palaeontologia Electronica |language=English |volume=15 |issue=3 |pages=1–22 |doi=10.26879/333 |issn=1094-8074 |doi-access=free}}</ref> 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. In ''Glyptotherium'', the occlusal lateral profile is slightly curved, whereas it is strongly curved in ''Glyptodon''. In ''Glyptodon'', the 1st molariform (abbreviated as mf1) 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=":110" />

The mandibles of ''Glyptotherium'' and ''Glyptodon'' are very similar, but ''Glyptotherium''<nowiki/>'s mandible is smaller by about 10%. The angle between the occlusal plane and the anterior margin of the ascending 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 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=":110" />

=== Carapace and osteoderms ===
[[File:Osteoderms_of_different_cingulates_-_Lima_et_al_2018.tif|alt=Osteoderms of Glyptotherium|left|thumb|246x246px|Osteoderm of ''Glyptotherium'' (A) and (B), displaying the "rossette" pattern]]
''Glyptotherium,'' and all other glyptodonts'','' had a large dorsal carapace covering much of the [[Dorsum (anatomy)|dorsum]] that was made up of interconnected osteoderms. The carapace of ''Glyptotherium'' was shorter than that of its relative ''Glyptodon'', but much more elongated than that of ''[[Boreostemma]].'' The high point of the carapace was at the center of the midline, while ''Glyptodon''{{'}}s was slightly displaced. ''Glyptotherium's'' carapace was strongly arched, with a convex pre-iliac and concave post-iliac, giving it a saddle-like overhang over the tail.<ref name=":110" /><ref name=":182">{{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 |url=https://doi.org/10.1080/02724634.2013.726677 |journal=Journal of Vertebrate Paleontology |volume=33 |issue=3 |pages=696–708 |bibcode=2013JVPal..33..696Z |doi=10.1080/02724634.2013.726677 |issn=0272-4634 |s2cid=86099989|hdl=11336/2971 |hdl-access=free }}</ref> In ''Glyptodon'' the top-bottom height of the carapace represents 60% of its total length, whereas in ''Glyptotherium'' it is taller at ca. 70%. The ventral margins of the carapace in ''Glyptotherium'' is much more rectangular and less convex than in ''Glyptodon.'' In ''Glyptotherium'', the osteoderms in the antero-lateral areas of the carapace are less ankylosed than in ''Glyptodon'', suggesting that the antero-lateral carapace regions of the former had more flexibility. The osteoderms of the caudal aperture are more conical in ''Glyptodon'' and more rounded in ''Glyptotherium'', though in the latter the anatomy of the caudal aperture osteoderms varies by sex<ref name=":142" /> while in ''Glyptodon'' it varies by age.<ref name=":242">{{Cite journal |last1=Zurita |first1=Alfredo Eduardo |last2=Soibelzon |first2=Leopoldo Hector |last3=Soibelzon |first3=Esteban |last4=Gasparini |first4=Germán Mariano |last5=Cenizo |first5=Marcos Martín |last6=Arzani |first6=Héctor |date=2010-01-01 |title=Accessory protection structures in Glyptodon Owen (Xenarthra, Cingulata, Glyptodontidae) |url=https://www.sciencedirect.com/science/article/pii/S0753396910000029 |journal=Annales de Paléontologie |language=en |volume=96 |issue=1 |pages=1–11 |bibcode=2010AnPal..96....1Z |doi=10.1016/j.annpal.2010.01.001 |issn=0753-3969}}</ref> Although frequently used to differentiate the two taxa, ''Glyptotherium'' and ''Glyptodon'' have very similar osteoderm morphologies that differ only in several areas. Both genera have very thick osteoderms compared to those of many South American glyptodonts like ''Hoplophorus'' and ''Neosclerocalyptus'', but ''Glyptotherium'' always preserve a "rossette" pattern, where the osteoderm's central figure is surrounded by a row of peripheral figures. Some ''Glyptodon'' specimens preserve these "rossettes", but others lack them. The central and radial [[Sulcus (morphology)|sulci]] are deeper and broader in ''Glyptodon'' (ca. 4–6&nbsp;mm) than in ''Glyptotherium'' (ca. 1–2.4&nbsp;mm).<ref name=":110" /><ref name=":142" /> Notably, ''Glyptotherium'' osteoderms preserve small gaps for hair follicles in the sulci that indicate that ''Glyptotherium'' had a "fuzzy" carapace with fur coming out. The number of follicles varies between ages and the area of the carapace, with juveniles having more follicles than adults, and fewer follicles are known from the lateral, caudal, and rear portions of the carapace.{{Sfn|Gillette|Ray|1981|p=169, 172, & 173}}<ref name=":142" />

=== Caudal rings ===
[[File:Glyptodon_tail_-_Cleveland_Museum_of_Natural_History_(34414489880).jpg|alt=Caudal tube of a glyptodont|thumb|Caudal rings of a glyptodont]]
''Glyptotherium'' is a glyptodont, meaning its caudal armor is made up of a series of caudal rings ending in a short caudal tube, in contrast to the mace-like ends in other glyptodonts, but the morphology differs between ''Glyptotherium, Glyptodon,'' and ''Boreostemma''. Overall, ''Boreostemma'' preserves a more similar caudal armor to ''Glyptotherium'' than to ''Glyptodon''.<ref name=":182" /> The caudal armor is longer in ''Glyptotherium'' than in ''Glyptodon'', with one specimen of ''G. texanum'' (UMMP 34 826) preserving a meter long set of caudal armor. In ''Glyptotherium'', the caudal armor length represents circa 50% of the dorsal carapace's total length, whereas in ''Glyptodon'', this value is lower at around 30-40%. ''Glyptodon'' has 8–9 complete caudal rings plus one caudal tube, but ''Glyptotherium'' preserves 1 incomplete caudal ring in addition to the 8–9 complete caudal rings and caudal tube. In both genera, each caudal ring is composed of two or three transverse rows of ankylosed osteoderms, where the distalmost row of osteoderms shows a more or less developed conical morphology. In ''Glyptotherium'', in some specimens (e.g., AMNH 95,737) a low number of conical osteoderms (generally two). This is different from ''Glyptodon'', in which most osteoderms of the distal row (up to 12) present a clear conical morphology. The terminal caudal tube is shorter in ''Glyptodon''. In ''Glyptotherium'', the terminal tube is composed of 2–3 ankylosed rings, whereas, in ''Glyptodon'', it has only two ankylosed rings. In ''Glyptotherium'', this caudal tube represents ca. 20% of the total length of the caudal armor, whereas in ''Glyptodon'', this structure represents 13% of the total length.<ref name=":110" />

== Paleobiology ==
=== Posture ===
Several interpretations of glyptodont posture have been made,<ref name=":272">{{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 |journal=Journal of Mammalian Evolution |language=en |volume=25 |issue=4 |pages=459–484 |doi=10.1007/s10914-017-9408-7 |issn=1573-7055 |s2cid=254693335 |doi-access=free}}</ref> initially by British paleontologist [[Richard Owen]] in 1841 using comparative anatomy.<ref name=":282">{{Cite journal |last=Owen |first=Richard |date=1841 |title=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. |url=https://www.lyellcollection.org/doi/10.1144/transgslb.6.1.81 |journal=Transactions of the Geological Society of London |language=en |volume=6 |issue=1 |pages=81–106 |doi=10.1144/transgslb.6.1.81 |issn=2042-5295}}</ref> Owen theorized that the phalanges were weight-bearing due to their short and broad physiology, in addition to the evidence provided in the postcranial skeleton.<ref name=":282" /> It was also proposed that an upright posture was possible for glyptodonts'','' first by Sénéchal (1865) who stated that the tail could be an equilibrium for the front half of the body as well as a method of supporting the legs.<ref name=":2522">Sénéchal, D. L. (1865). ''Notice sur l'armure ou le dermato-squelette et le système dentaire du Glyptodon clavipes, et particularités biologiques de cet animal, déduites d'après l'étude de ses restes fossiles''. Balitout, Questroy et Cie.</ref><ref name=":272" /> Linear measurements were later taken which provided insight into this hypothesis, finding that bipedalism would be possible.<ref>Fari a, R. A., & Vizcaíno, S. F. (1997). Allometry of the bones of living and extinct armadillos (Xenarthra, Dasypoda). ''Zeitschrift fur Saugetierkunde'', ''62'', 65-70.</ref><ref>{{Cite journal |last1=Fariña |first1=Richard A. |last2=Vizcaı́no |first2=Sergio F. |last3=Blanco |first3=R. Ernesto |date=1997-04-21 |title=Scaling of the Indicator of Athletic Capability in Fossil and Extant Land Tetrapods |url=https://www.sciencedirect.com/science/article/pii/S0022519396903239 |journal=Journal of Theoretical Biology |language=en |volume=185 |issue=4 |pages=441–446 |bibcode=1997JThBi.185..441F |doi=10.1006/jtbi.1996.0323 |issn=0022-5193}}</ref> The patellar articulation with the femur suggests rotation of the crus during knee extension and potentially even knee-locking were feasible.<ref>Shockey, B. J. (2001). Specialized knee joints in some extinct, endemic, South American herbivores. ''Acta Palaeontologica Polonica'', ''46''(2).</ref>

=== Feeding and diet ===
[[File:Jackson_Zoo_Pygmy_Hippopotamus.jpg|alt=A Pygmy hippopotamus|left|thumb|A [[Pygmy hippopotamus]], which has been suggested to have had a similar ecology to ''Glyptotherium.'']]
''Glyptotherium'' is traditionally thought to consume wet, [[Riparian zone|riparian]] [[herb]]s.<ref name=":0">{{Cite journal |last1=Russell |first1=Dale A. |last2=Rich |first2=Fredrick J. |last3=Schneider |first3=Vincent |last4=Lynch-Stieglitz |first4=Jean |date=May 2009 |title=A warm thermal enclave in the Late Pleistocene of the South-eastern United States |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.2008.00069.x |journal=Biological Reviews |language=en |volume=84 |issue=2 |pages=173–202 |doi=10.1111/j.1469-185X.2008.00069.x |pmid=19391200 |s2cid=9609391 |issn=1464-7931}}</ref> The genus was mainly a grazer but also had a mixed diet of [[C3 carbon fixation|C3]] and [[C4 carbon fixation|C4]] plants based on [[Isotope analysis|isotope analyses]] of dental specimens recovered from the [[Late Pleistocene]] Cedral locality in [[San Luis Potosí]], México.<ref name=":92">Pérez-Crespo, V. A., Arroyo-Cabrales, J., Alva-Valdivia, L. M., Morales-Puente, P., & Cienfuegos-Alvarado, E. (2012). Diet and habitat definitions for Mexican glyptodonts from Cedral (San Luis Potosí, México) based on stable isotope analysis. ''Geological Magazine'', ''149''(1), 153-157.</ref> The locality preserves C4 plants from the families [[Poaceae|Poacea]], [[Amaranthaceae|Amaranthacea]] and [[Quenopodiacea]],<ref name=":152">Keeley, J. E., & Rundel, P. W. (2003). Evolution of CAM and C4 carbon-concentrating mechanisms. ''International journal of plant sciences'', ''164''(S3), S55-S77.</ref> meaning that they were possible food sources for ''Glyptotherium''.<ref name=":92" /> Cedral specifically was an area with hot springs and open grasslands next to them, suggesting that ''Glyptotherium'' fed in grasslands near water sources, like the feeding habits of modern [[capybara]]s.{{Sfn|Gillette|Ray|1981|p=202}}<ref name=":92" /> Additional isotopic analysis of ''Glyptotherium'' and the giant ground sloth ''[[Eremotherium]]'' found the two to have similar isotopic levels to the extant amphibious ''[[Hippopotamus]]'', indicating that they were semi-aquatic herbivores that fed on aquatic plants. Additional studies of dental specimens from eastern Brazil suggest that the ''Glyptotherium'' were grazers in moist, lowland tropical to subtropical habitats along rivers or water sources, supporting the semi-aquatic ''Glyptotherium'' hypothesis.<ref name=":222" /><ref name=":132" /><ref name=":162">{{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 (δ13C), niche differentiation, guilds and paleoenvironmental reconstruction (δ13C, δ18O) |url=https://doi.org/10.1080/08912963.2020.1789977 |journal=Historical Biology |volume=33 |issue=10 |pages=2299–2304 |doi=10.1080/08912963.2020.1789977 |bibcode=2021HBio...33.2299O |issn=0891-2963 |s2cid=225543776}}</ref> Additional isotopic evidence from Brazil suggests that fruits were also part of ''Glyptotherium'' diets, though only around 20% total.<ref>Dantas, M. A. T., Cherkinsky, A., Lessa, C. M. B., Santos, L. V., Cozzuol, M. A., Omena, É. C., ... & Bocherens, H. (2020). Isotopic paleoecology (δ13C, δ18O) of a late Pleistocene vertebrate community from the Brazilian Intertropical Region. ''Revista Brasileira de Paleontologia'', ''23''(2), 138-152.</ref> ''Glyptotherium'' and all other glyptodonts had hypsodont teeth, high-crowned teeth with rough, flat surfaces adapted for grinding and crushing, that were adapted to break down gritty, fibrous material like grasses.<ref>Phillip E. Jardine, Christine M. Janis, Sarda Sahney, Michael J. Benton. "Grit not grass: Concordant patterns of early origin of hypsodonty in Great Plains ungulates and Glires." Palaeogeography, Palaeoclimatology, Palaeoecology. December 2012:365–366, 1–10</ref>{{Sfn|Gillette|Ray|1981|p=202}} This diet for ''Glyptotherium'' contrasts with those surmised for their relatives [[Pampatheriidae|Pampatheres]], which have been considered insectivores or grazers.<ref name=":92" /><ref>{{Cite journal |last1=De Iuliis |first1=Gerardo |last2=Bargo |first2=María S. |last3=Vizcaíno |first3=Sergio F. |date=2001-01-19 |title=Variation in skull morphology and mastication in the fossil giant armadillos Pampatherium spp. and allied genera (Mammalia: Xenarthra: Pampatheriidae), with comments on their systematics and distribution |url=https://doi.org/10.1671/0272-4634(2000)020[0743:VISMAM]2.0.CO;2 |journal=Journal of Vertebrate Paleontology |volume=20 |issue=4 |pages=743–754 |doi=10.1671/0272-4634(2000)020[0743:VISMAM]2.0.CO;2 |issn=0272-4634 |s2cid=86263866}}</ref> Like most other xenarthrans, glyptodonts had lower energy requirements than most other mammals. They could survive with lower intake rates than other herbivores with similar mass.<ref>Vizcaíno, Sergio F.; Cassini, Guillermo H.; Fernicola, Juan C.; Bargo, M. Susana (2011). "Evaluating Habitats and Feeding Habits Through Ecomorphological Features in Glyptodonts (Mammalia, Xenarthra)". Ameghiniana: 305–319. {{doi|10.5710/AMGH.v48i3(364)}}. {{s2cid|85793531}}. Retrieved 2015-10-29.</ref>

=== Digging abilities ===
Many extant species of armadillo have digging capabilities, with large claws adapted for scraping dirt to make burrows or forage for food underground.<ref>Vizcaíno, S. F., Fariña, R. A., & Mazzetta, G. V. (1999). Ulnar dimensions and fossoriality in armadillos. ''Acta Theriologica'', ''44''.</ref><ref>Carter, T. S., & Encarnaçao, C. D. (1983). Characteristics and use of burrows by four species of armadillos in Brazil. ''Journal of Mammalogy'', ''64''(1), 103-108.</ref> Also, much of their diet consists of insects and other invertebrates that live underground,<ref>{{Cite journal |last1=Vizcaíno |first1=Sergio F. |last2=Fariña |first2=Richard A. |date=2007-03-29 |title=Diet and locomotion of the armadillo Peltephilus: a new view |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1502-3931.1997.tb00446.x |journal=Lethaia |language=en |volume=30 |issue=1 |pages=79–86 |doi=10.1111/j.1502-3931.1997.tb00446.x}}</ref> in contrast to the herbivorous diets of ''Glyptotherium''.<ref>{{Cite journal |last1=Saarinen |first1=Juha |last2=Karme |first2=Aleksis |date=2017-06-15 |title=Tooth wear and diets of extant and fossil xenarthrans (Mammalia, Xenarthra) – Applying a new mesowear approach |url=https://www.sciencedirect.com/science/article/pii/S0031018216306630 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=476 |pages=42–54 |bibcode=2017PPP...476...42S |doi=10.1016/j.palaeo.2017.03.027 |issn=0031-0182}}</ref> Being from the armadillo family, glyptodont fossorial capabilities have been researched on several occasions.<ref name=":272" /> Owen (1841) opposed this idea, though pushback came from Nodot (1856) and Sénéchal (1865) who believed digging was possible for the genus.<ref name=":272" /><ref name=":282" /> However, the evolution of a rigid carapace as opposed to a flexible one in extant armadillos as well as a weakly developed [[Humerus|deltoid crest]] on the humerus (upper arm bone) provided evidence against fossorial hypotheses. The elbow had a great range of movement, as with digging cingulates, but this is more likely to be due to size adaptations.<ref>{{Cite journal |last1=Vizcaíno |first1=Sergio F. |last2=Blanco |first2=R. Ernesto |last3=Bender |first3=J. Benjamín |last4=Milne |first4=Nick |date=2011 |title=Proportions and function of the limbs of glyptodonts: Glyptodont limbs |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1502-3931.2010.00228.x |journal=Lethaia |language=en |volume=44 |issue=1 |pages=93–101 |doi=10.1111/j.1502-3931.2010.00228.x|bibcode=2011Letha..44...93V }}</ref><ref name=":272" />

=== 
Juvenile and adult specimens of ''Glyptotherium texanum'' found in Blancan localities in Arizona preserve a nearly complete growth series, one of the few known in glyptodonts.<ref name=":142" /> The teeth of ''Glyptotherium'' preserve hypsodonty, where the teeth do not stop growing.<ref name=":142" /> In the juveniles, fully articulated osteoderm-to-osteoderm contact is already known, even at their age.<ref name=":142" /> Growth of the osteoderms continued from juveniles to sub-adults and ceased when osteoderms became ankylosed (fused).<ref name=":102" /><ref name=":142" /> The lateral profile of juvenile carapaces are gently convex into the high-arched carapaces of adults. Another ontogenetic change is in the sulci and peripheral figures of the osteoderms; the central figures are the largest relative to the sulci in newborns and juveniles, but this ratio becomes lower in adults. In ''G. cylindricum,'' however, the osteoderms grow much faster and the sulci are much smaller. The osteoderms are also relatively thicker in juvenile ''Glyptotherium'' individuals compared to adults.<ref name=":142" />

=== Sexual dimorphism ===
Individuals of ''Glyptotherium texanum'' found in Blancan localities in Arizona preserve sexual dimorphism between male and female individuals. The caudal aperture, large conical osteoderms that protect the base of the tail, of males and females differ in that the marginal osteoderms of males are much more conical and convex than those of females. Even in the carapaces of newborn ''Glyptotherium'', the marginal osteoderms are either conical or flat, which enables their sex to be determined.<ref name=":142" />

=== Osteoderms and protection ===
[[File:Glyptotherium_floridanum.jpg|thumb|A carapace and caudal armor of ''G. cylindricum.'']]
[[Osteoderm]]s of ''Glyptotherium'' are made of a [[Bone|cancellous]] trabecular core in between two compact layers. Each hexagonal osteoderm is joined to the adjacent osteoderms with sutures, creating a large, robust carapace similar to those in modern animals. However, the carapaces of glyptodonts like ''Glyptotherium'' were far less flexible than those of modern armadillos.<ref>{{Cite journal |last1=Chen |first1=Irene H. |last2=Kiang |first2=James H. |last3=Correa |first3=Victor |last4=Lopez |first4=Maria I. |last5=Chen |first5=Po-Yu |last6=McKittrick |first6=Joanna |last7=Meyers |first7=Marc A. |date=2011-07-01 |title=Armadillo armor: Mechanical testing and micro-structural evaluation |url=https://www.sciencedirect.com/science/article/pii/S1751616110001888 |journal=Journal of the Mechanical Behavior of Biomedical Materials |series=Special Issue on Natural Materials / Papers from the Third International Conference on the Mechanics of Biomaterials and Tissues |language=en |volume=4 |issue=5 |pages=713–722 |doi=10.1016/j.jmbbm.2010.12.013 |issn=1751-6161 |pmid=21565719}}</ref> The trabecular core was made up of struts used for support with an average thickness of 0.25&nbsp;mm, these struts making up the central support of the osteoderm. Mechanical analyses revealed that smaller load areas, representing sharper objects, cause higher stresses than those caused by large, blunt objects. This can be understood as the natural structure evolved to withstand blunt impact from large objects such as tail-clubs and not as protection against sharp objects such as teeth.<ref name=":82" /> This presents further evidence for the theory that glyptodonts used their carapaces for intraspecific combat using tail clubs as well as defense.<ref name=":82" />

=== Disease and pathologies ===
A partial postcranial skeleton of ''Glyptotherium cylindricum'' found in northeastern Brazil that included partial limbs preserved 3 different types of arthritis: one type of inflammatory arthritis ([[spondyloarthropathy]]), one type of crystalline arthritis ([[Calcium pyrophosphate dihydrate crystal deposition disease|calcium pyrophosphate deposition disease]]) and one proliferative arthritis ([[osteoarthritis]]). Spondyloarthropathy was the most prevalent, with bone erosion on the right ulna, right and left radii, a left femur and both right and left tibiae-fibulae and is associated with bone sclerosis on the right ulna and radius. Calcium pyrophosphate deposition disease is present on the articular surface of the left patella and osteoarthritis is represented by [[osteophyte]]s on some of the left hindlimb.<ref>{{Cite journal |last1=Barbosa |first1=Fernando Henrique de Souza |last2=Porpino |first2=Kleberson de Oliveira |last3=Fragoso |first3=Ana Bernadete Lima |last4=Oliveira |first4=Edison Vicente |date=2014-02-13 |title=Arthritis in a Glyptodont (Mammalia, Xenarthra, Cingulata) |journal=PLOS ONE |language=en |volume=9 |issue=2 |pages=e88646 |bibcode=2014PLoSO...988646B |doi=10.1371/journal.pone.0088646 |issn=1932-6203 |pmc=3923812 |pmid=24551126 |doi-access=free}}</ref> On several osteoderms that were also found in Brazil, ectoparasitism, lesions, and growths were found, some of these infections were likely caused by fleas.<ref>{{Cite journal |last1=Lima |first1=Fábio Cunha Guimarães de |last2=Porpino |first2=Kleberson de Oliveira |date=2018-10-18 |title=Ectoparasitism and infections in the exoskeletons of large fossil cingulates |journal=PLOS ONE |language=en |volume=13 |issue=10 |pages=e0205656 |bibcode=2018PLoSO..1305656D |doi=10.1371/journal.pone.0205656 |issn=1932-6203 |pmc=6193641 |pmid=30335796 |doi-access=free}}</ref>

== Paleoecology ==
''Glyptotherium'' was primarily a grazer in forested grasslands and arboreal savannahs, though they may have preferred grasslands near water sources based on fossils localities from Mexico.<ref name=":92" /> Due to their wide distribution, ''Glyptotherium''{{'}}s paleoecology may have varied across regions and its 2 species.<ref name=":132" /><ref name=":92" /> 
[[File:A-Pleistocene-meso-megamammals-from-Sergipe-Brazil.jpg|alt=Restoration of the grassland ecosystem present in the Brazilian Intertropical Region|left|thumb|291x291px|Restoration of the grassland ecosystem present in the Brazilian Intertropical Region]]
In North America, ''Glyptotherium'' is known from 2 different species that lived in 3 different intervals, the [[Blancan]], [[Irvingtonian]], and [[Rancholabrean]], across several US states and Mexico.<ref name=":110" /> However, ''Glyptotherium'' has not been found in Pacific drainages in the United States or west of the [[Colorado River]],<ref name=":110" /> being instead present largely in the [[Atlantic Plain]] and [[Interior Plains]].<ref name=":35" /> During the Blancan, ''Glyptotherium texanum'' coexisted with many endemic genera from North America, as [[Beringia]] had not yet formed. Because of this, the fauna of the Blancan starkly contrasted with the fauna of the proceeding [[Pleistocene]]. The Blancan age strata of western Texas, New Mexico, and Arizona preserves the gomphothere proboscideans ''[[Stegomastodon]]'' and ''[[Cuvieronius]]'', equids represented by grazers like ''[[Nannippus|Nannipus]]'' and ''[[Equus (genus)|Equus]].'' Other xenarthrans are also known, like the megalonychid ground sloth ''[[Megalonyx]]'' and the mylodontid ''[[Paramylodon]].'' Fossils of small mammals have also been unearthed, like the insectivores ''[[Hesperoscalops]]'' and ''[[Sorex]].'' A giant fossil ground squirrel, ''[[Paenemarmota]]'', is also known from the Blancan.<ref>Repenning, Charles A. (1962). "[https://www.jstor.org/stable/1301086 The Giant Ground Squirrel ''Paenemarmota'']". ''[[Journal of Paleontology]]''. '''36''' (93): 540–556. [[JSTOR (identifier)|JSTOR]] 1301086.</ref> The carnivores include the unusual "bone-crushing" dog relative ''[[Borophagus]]'' and the "running hyena" ''[[Chasmaporthetes]],''<ref name=":172">Dalquest, W. W. (1975). [https://www.biodiversitylibrary.org/bibliography/142927 Vertebrate fossils from the Blanco local fauna of Texas.]</ref> in addition to the "saber-toothed" cat ''[[Smilodon|Smilodon gracilis]]''.<ref>Martin, L. D., Schultz, C. B., & Schultz, M. R. (1988). [https://digitalcommons.unl.edu/tnas/186/ Saber-toothed cats from the Plio-Pleistocene of Nebraska.]</ref> Some isolated bird fossils have also been found consisting of vultures, falcons, and possibly corvids.<ref name=":172" /><ref>{{Cite journal |last1=Feduccia |first1=J. Alan |last2=Ford |first2=Norman L. |date=1970-10-01 |title=Some birds of prey from the Upper Pliocene of Kansas |url=https://doi.org/10.2307/4083714 |journal=The Auk |volume=87 |issue=4 |pages=795–797 |doi=10.2307/4083714 |issn=1938-4254 |jstor=4083714}}</ref><ref>{{Cite journal |last=Marshall |first=William H. |date=1937-01-01 |title=Double-crested Cormorant Nesting on the Bear River Refuge in Utah |url=https://doi.org/10.2307/1363487 |journal=The Condor |volume=39 |issue=1 |pages=36 |doi=10.2307/1363487 |issn=1938-5129 |jstor=1363487}}</ref> Fossils from Guatemala were found from high altitudes, showing that ''Glyptotherium'' was highly adaptable and could live in a variation of environments.<ref name=":112"/> This is supported by the generalist diet of ''Glyptotherium'' and fossil's discoveries in tropical, subtropical, forested, and even semi-aquatic environments. In the Mexican state of Yucatan, fossils of ''Glyptotherium'' and the ground sloth ''Paramylodon'' are known from water-rich areas like riparian forests and swamps as opposed to open grasslands.<ref>Stinnesbeck, S. R. (2020). Mexican fossil ground sloths-A case study for Late Pleistocene megafaunal turnover in the Mexican Corridor.</ref>

In the Brazilian Intertropical Region (BIR) in eastern Brazil, ''Glyptotherium'' was a mixed grazer in arboreal savannahs, tropical grasslands, and other grassy areas near water sources. Large, mesoherbivore mammals in the BIR were widespread and diverse, including the cow-like [[Toxodontidae|toxodontids]] ''[[Toxodon|Toxodon platensis]]'' and ''[[Piauhytherium]]'', the [[Macraucheniidae|macraucheniid]] [[Litopterna|litoptern]] ''[[Xenorhinotherium]]'' and equids such as ''[[Hippidion|Hippidion principale]]'' and ''[[Amerhippus|Equus neogaeus]].'' Toxodontids were large mixed feeders as well and lived in forested areas, while the equids were nearly entirely grazers. Other xenarthran fossils are present in the area as well from several different families, like the giant [[Megatheriidae|megatheriid]] [[ground sloth]] ''[[Eremotherium]],'' the [[Scelidotheriidae|scelidotheriids]] ''[[Catonyx]]'' and ''[[Valgipes]]'', the [[Mylodontidae|mylodontids]] ''[[Glossotherium]]'', ''[[Ocnotherium]]'', and ''[[Mylodonopsis]]''. Smaller ground sloths such as the [[Megalonychidae|megalonychids]] ''[[Ahytherium]]'' and ''[[Australonyx]]'' and the [[Nothrotheriidae|nothrotheriid]] ''[[Nothrotherium]]'' have also been found in the area. ''Eremotherium'' was a generalist, while ''Nothrotherium'' was a specialist for trees in low density forests, and ''Valgipes'' was an intermediate of the two that lived in arboreal savannahs. Other glyptodonts and [[Cingulata|cingulates]] like the grazing glyptodont ''[[Panochthus]]'' and the omnivorous [[Pampatheriidae|pampatheres]] ''[[Pampatherium]]'' and ''[[Holmesina]]'' were present in the open grasslands. A [[proboscidea]]n species has also been found in the BIR, ''[[Notiomastodon|Notiomastodon platensis]],'' was also present and was a mixed grazer on the open grasslands. Carnivores included some of the largest known mammalian carnivores, like the giant felid ''[[Smilodon|Smilodon populator]]'' and the bear ''[[Arctotherium|Arctotherium wingei]].''<ref name=":152" /><ref name=":162" /> Several extant taxa are also known from the BIR, like [[guanaco]]s, [[giant anteater]]s, [[Collared peccary|collared peccaries]], and [[striped hog-nosed skunk]]s.<ref name=":212">Cartelle, Castor; Hartwig, W. C. (1996). "A new extinct primate among the Pleistocene megafauna of Bahia, Brazil". Proceedings of the National Academy of Sciences. '''93''' (13): 6405–6409.</ref> Two crab-eating types of extant mammals are also known from the BIR, the [[crab-eating raccoon]] and the [[crab-eating fox]], indicating that crabs were also present in the region.<ref name=":212" /> The environment of the BIR is unclear, as there were both several species that were grazers, but the precede of the arboreal fossil monkeys ''[[Protopithecus]]'' and ''[[Caipora bambuiorum|Caipora]]'' in the area causes confusion over the area's paleoenvironment. Most of [[Brazil]] was thought to have been covered in open tropical [[cerrado]] vegetation during the Late Pleistocene, but if ''Protopithecus'' and ''Caipora'' were arboreal, their presence suggests that the region may have supported a dense closed forest during the Late Pleistocene.<ref name=":212" /><ref>Eisenberg, John F.; Redford, Kent H. (1989). Mammals of the Neotropics, Volume 3: Ecuador, Bolivia, Brazil. University of Chicago Press. p. 247. {{ISBN|978-0-226-19542-1}}.</ref> It is possible that the region alternated between dry open savanna and closed wet forest throughout the climate change of the Late Pleistocene.<ref>Halenar, Lauren B. (December 2011). "Reconstructing the Locomotor Repertoire of Protopithecus brasiliensis". The Anatomical Record. '''294''' (12): 2048–2063.</ref>

=== Great American Interchange ===
[[File:Great_American_Biotic_Interchange_examples.svg|alt=Map of the Great American Interchange|left|thumb|Examples of fauna that participated in the [[Great American Interchange]].]]
South America, the continent where glyptodonts originated, was isolated after the breakup of the landmass [[Gondwana]] at the end of the [[Mesozoic]] era.<ref name=":302">{{Cite journal |last=David Webb |first=S. |date=2006-08-23 |title=The Great American Biotic Interchange: Patterns and Processes1 |url=http://www.bioone.org/doi/abs/10.3417/0026-6493%282006%2993%5B245%3ATGABIP%5D2.0.CO%3B2 |journal=Annals of the Missouri Botanical Garden |language=en |volume=93 |issue=2 |pages=245–257 |doi=10.3417/0026-6493(2006)93[245:TGABIP]2.0.CO;2 |issn=0026-6493 |s2cid=198152030}}</ref> This period of separation from the rest of the Earth's continents led to an age of unique mammalian evolution, with the dominance of groups such as [[marsupial]]s, xenarthrans, and [[Notoungulata|notoungulates]] in contrast to the North American mammal fauna. Marsupials likely got to South America prior to its separation from the rest of Gondwana in the [[Late Cretaceous]] or [[Paleogene]], although the origins of mammalian orders like Xenarthra and Notoungulata ended up on the continent remains a mystery.<ref>{{Cite journal |last=Charrier |first=John J. Flynn, André R. Wyss and Reynaldo |year=2007 |title=South America's Missing Mammals |url=https://www.scientificamerican.com/article/south-americas-missing-mammals/ |journal=Scientific American |language=en |volume=296 |issue=5 |pages=68–75 |bibcode=2007SciAm.296e..68F |doi=10.1038/scientificamerican0507-68 |pmid=17500416 |access-date=2023-05-09}}</ref> There were several movements of outside mammals to South America prior to the formation of the [[Isthmus of Panama]], such as with [[primate]]s and [[rodent]]s which may have rafted to the continent from Africa and the movement of [[bat]]s via flight.<ref>Bloch, J. I., Woodruff, E. D., Wood, A. R., Rincon, A. F., Harrington, A. R., Morgan, G. S., ... & MacFadden, B. J. (2016). First North American fossil monkey and early Miocene tropical biotic interchange. ''Nature'', ''533''(7602), 243-246.</ref><ref>Croft, D. A. (2016). ''Horned armadillos and rafting monkeys: the fascinating fossil mammals of South America''. Indiana University Press.</ref> As for the fauna of North America, contemporary groups like canids, felids, [[Bear|ursids]], [[tapir]]ids, [[Antilocapridae|antilocaprids]], and equids populated the region in addition to extinct families like gomphotheres, amphicyonids, and [[Mammutidae|mammutids]].<ref>Morgan, G. S. (2005). The great American biotic interchange in Florida. ''Bulletin of the Florida Museum of Natural History'', ''45''(4), 271-311.</ref><ref name=":302" /> The Great American Interchange did not enter its biggest stage until the Isthmus of Panama formed 2.7 million years ago during the Blancan stage of the Pliocene.<ref>McDonald, H. G. (2005). Palecology of extinct xenarthrans and the Great American Biotic Interchange. ''Bulletin of the Florida Museum of Natural History'', ''45''(4), 319-340.</ref><ref name=":322">{{Cite journal |last1=Scillato-Yané |first1=G. J. |last2=Carlini |first2=A. A. |last3=Tonni |first3=E. P. |last4=Noriega |first4=J. I. |date=2005-10-01 |title=Paleobiogeography of the late Pleistocene pampatheres of South America |url=https://www.sciencedirect.com/science/article/pii/S0895981105001288 |journal=Journal of South American Earth Sciences |series=Quaternary Paleontology and biostratigraphy of southern South Africa |language=en |volume=20 |issue=1 |pages=131–138 |bibcode=2005JSAES..20..131S |doi=10.1016/j.jsames.2005.06.012 |issn=0895-9811 |hdl-access=free |hdl=11336/80762}}</ref><ref name=":332">{{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 |url=https://doi.org/10.1007/BF02988404 |journal=Paläontologische Zeitschrift |language=en |volume=82 |issue=2 |pages=125–138 |doi=10.1007/BF02988404 |bibcode=2008PalZ...82..125C |issn=0031-0220 |eissn=1867-6812 |s2cid=128528271|hdl=11336/36844 |hdl-access=free }}</ref> This intensified movement of glyptodonts, ground sloths, capybaras, pampatheres, [[Phorusrhacidae|terror birds]], and marsupials to North America via the Central America route and a reverse migration of ungulates, proboscideans, felids, canids, and many other megafauna groups to South America.<ref name=":312">Cione, A. L., Gasparini, G. M., Soibelzon, E., Soibelzon, L. H., & Tonni, E. P. (2015). ''The great American biotic interchange: a South American perspective'' (p. 97). Dordrecht: Springer.</ref> The period following the Isthmus' foundation witnessed the extinction or extirpation of many groups, including the South American terror birds, toxodonts, [[Macraucheniidae|macraucheniids]], pampatheres, ground sloths, and glyptodonts.<ref>Woodburne, M. O. (2010). The Great American Biotic Interchange: dispersals, tectonics, climate, sea level and holding pens. ''Journal of mammalian evolution'', ''17'', 245-264.</ref><ref>{{Cite journal |last1=Lundelius |first1=Ernest L. |last2=Bryant |first2=Vaughn M. |last3=Mandel |first3=Rolfe |last4=Thies |first4=Kenneth J. |last5=Thoms |first5=Alston |date=2013-01-01 |title=The first occurrence of a toxodont (Mammalia, Notoungulata) in the United States |url=https://doi.org/10.1080/02724634.2012.711405 |journal=Journal of Vertebrate Paleontology |volume=33 |issue=1 |pages=229–232 |bibcode=2013JVPal..33..229L |doi=10.1080/02724634.2012.711405 |issn=0272-4634 |s2cid=53601518 |hdl-access=free |hdl=1808/13587}}</ref>

''Glyptotherium'' itself was part of this interchange, evolving in the Blancan of the Mexico & the USA after the formation of the Isthmus and its immigration.<ref name=":110" /><ref name=":312" /> The geographic isolation of ''Glyptotherium'' in combination to adaptations to the different environments of North America led to ''Glyptotherium'' breaking off from other glyptodontines.<ref name=":110" />

Though ''G. texanum'' evolved in North American into ''G. cylindricum'' in the Rancholabrean, it emigrated southwards to Central and parts of northern South America circa 15,000-20,000 BP.<ref name=":42" /><ref name=":52" /><ref name=":1">{{Cite journal |last1=Zurita |first1=Alfredo E. |last2=Carlini |first2=Alfredo A. |last3=Gillette |first3=David |last4=Sánchez |first4=Rodolfo |date=2011-03-01 |title=Late Pliocene Glyptodontinae (Xenarthra, Cingulata, Glyptodontidae) of South and North America: Morphology and paleobiogeographical implications in the GABI |url=https://www.sciencedirect.com/science/article/pii/S0895981111000095 |journal=Journal of South American Earth Sciences |volume=31 |issue=2 |pages=178–185 |doi=10.1016/j.jsames.2011.02.001 |bibcode=2011JSAES..31..178Z |hdl=11336/41714 |issn=0895-9811|hdl-access=free }}</ref> This is also connected to ecological segregation, with [[Andean natural region|mountain barriers]] in [[Colombia]] possibly separating ''Glyptodon'' and ''Glyptotherium''.<ref name=":192" /> Subsequently, ''Glyptodon'' lived primarily in Andean and coastal sites, with ''Glyptotherium'' being known from grassland and lightly forested lowland deposits near aquatic areas, motivating its dispersal to the tropical regions of Venezuela and eastern Brazil.<ref name=":332" /><ref name=":132" /><ref>Pujos, F., & Salas, R. (2004). A systematic reassessment and paleogeographic review of fossil Xenarthra from Peru. ''Bulletin de l'Institut français d'études andines'', (33 (2)), 331-377.</ref> The re-entrance of a group to South America from North America has also been observed in the related cingulate family Pampatheriidae,<ref name=":322" /> possibly aided by wide coastal lowlands uncovered during glacial periods on the Caribbean and Atlantic coasts, allowing migration between Florida, Mexico, Central America, and/or northern South America.<ref name=":332" /><ref>{{Cite journal |last1=Rabassa |first1=Jorge |last2=Coronato |first2=Andrea M. |last3=Salemme |first3=Mónica |date=2005-10-01 |title=Chronology of the Late Cenozoic Patagonian glaciations and their correlation with biostratigraphic units of the Pampean region (Argentina) |url=https://www.sciencedirect.com/science/article/pii/S0895981105001276 |journal=Journal of South American Earth Sciences |series=Quaternary Paleontology and biostratigraphy of southern South Africa |language=en |volume=20 |issue=1 |pages=81–103 |bibcode=2005JSAES..20...81R |doi=10.1016/j.jsames.2005.07.004 |issn=0895-9811 |hdl-access=free |hdl=11336/150967}}</ref>

{{Multiple image
| image1            = Glyptotherium texanum.JPG
| image2            = Glyptotherium AMNH.jpg
| direction         = vertical
| footer            = ''G. texanum'' skull from [[Arizona]], preserving bite marks from a ''Smilodon'' on the skull roof.
| total_width       = 190
}}

=== Predation ===
''[[Smilodon]]'' may have occasionally preyed upon ''Glyptotherium'', based on a skull from one ''Glyptotherium texanum'' individual recovered from Pleistocene deposits in Arizona bearing 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=":253">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 glyptodonts.<ref name=":262">Bohlin, B. (1940). 8. Food habit of the machairodonts, with special regard to ''Smilodon''.</ref>

Brandes hypothesized that the evolution of thick glyptodont armor and long machairodont canines was an example of coevolution,<ref name=":253" /> but Birger Bohlin argued in 1940 that the canines were far too fragile to do damage against glyptodont armor.<ref name=":262" /><ref name=":242" /> However, the evolution of accessory protection structures may have been in response to the arrival of ''Smilodon'' and ''Arctotherium'' in the [[Ensenadan]].<ref name=":242" />

In 2017, a right ulna of an adult ''Glyptotherium'' that had been collected from Late Pleistocene strata in Rio Grande do Norte State, Brazil was described that bore several gnawing traces from a new ichnospecies of ''[[Machichnus]], M. fatimae'', that may have been caused by a juvenile of the canid species ''[[Protocyon|Protocyon troglodytes]]'' or an adult individual of ''[[Crab-eating fox|Cerdocyon thous]].''<ref>{{Cite journal |last1=Araújo-Júnior |first1=Hermínio Ismael de |last2=Barbosa |first2=Fernando Henrique de Souza |last3=Silva |first3=Lucas Henrique Medeiros da |date=2017-02-15 |title=Overlapping paleoichnology, paleoecology and taphonomy: Analysis of tooth traces in a Late Pleistocene-early Holocene megafaunal assemblage of Brazil and description of a new ichnotaxon in hard substrate |url=https://www.sciencedirect.com/science/article/pii/S0031018216308379 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |language=en |volume=468 |pages=122–128 |bibcode=2017PPP...468..122A |doi=10.1016/j.palaeo.2016.12.007 |issn=0031-0182}}</ref>

== Relationship with humans ==
[[File:Glyptotherium_cylindricum_skull_AMU-CURS-1287(MTT-V)_with_human-caused_pathologies.webp|alt=G. cylindricum skull preserving pathologies caused by humans|left|thumb|274x274px|Diagram showing pathologies inflicted on a ''G. cylindicum'' skull by humans from Falcón, Venezuela.]]
The first report of possible human consumption or interaction with ''Glyptotherium'' or its fossils came in 1958, where several osteoderms that were possibly consumed by humans were described from the [[Clovis culture|Clovis]] site in [[Lewisville, Texas|Lewisville]], Texas.<ref>{{Cite journal |last1=Crook |first1=Wilson W. |last2=Harris |first2=R. K. |date=1958 |title=A Pleistocene Campsite near Lewisville, Texas |url=https://www.cambridge.org/core/journals/american-antiquity/article/abs/pleistocene-campsite-near-lewisville-texas/D4C1AFD4056ABC2C66B5599CFCE8938C |journal=American Antiquity |language=en |volume=23 |issue=3 |pages=233–246 |doi=10.2307/276304 |issn=0002-7316 |jstor=276304 |s2cid=161227132}}</ref><ref>{{Cite journal |last1=Waguespack |first1=Nicole M. |last2=Surovell |first2=Todd A. |date=2003 |title=Clovis Hunting Strategies, or How to Make out on Plentiful Resources |url=https://www.cambridge.org/core/journals/american-antiquity/article/abs/clovis-hunting-strategies-or-how-to-make-out-on-plentiful-resources/F5D7B9E8721919E3E3823C9BF89E37FA |journal=American Antiquity |language=en |volume=68 |issue=2 |pages=333–352 |doi=10.2307/3557083 |issn=0002-7316 |jstor=3557083 |s2cid=164047864}}</ref> This idea of human consumption has little evidence to back it, however.<ref name=":42" /> In 2022, a host of fossils of ''Glyptotherium cylindricum'' including skulls were described that had been collected from several sites in [[Falcón]], northern Venezuela that dated to the [[Late Pleistocene]].<ref name=":42" /> These discoveries were notable not only because they preserved skulls, but four of them exhibited breakages in the fronto-parietal region, a pattern in all of the skulls. Visual and CT evidence indicates that these were likely caused by a mechanical effect by direct percussion, most likely a blow with a stone chopper or club, which caused the bones in the region to fragment into the soft internal tissues of the skull. Despite the fact that the skulls were complete and showed no signs of taphonomic distortion or transport, they often lacked their jaws. The jaws may have been removed for "hunters" to access and consume masticatory muscles and tongue. The coexistence of early hunter-gatherer humans and glyptodonts in South America was first hypothesized in 1881 based on fossil discoveries from the [[Pampas|Argentine Pampas]],<ref>Vogt, C. (1881). Squelette humain associe aux glyptodontidae. Bulletin de la Société d'Antropologie de Paris, 3(4), 693–699</ref> and many fossil discoveries from the Late Pleistocene have been unearthed since that exhibit human predation on glyptodonts. During this period, a wide array of Xenarthrans inhabited the Pampas were hunted by humans, with evidence demonstrating that the small (300–450&nbsp;kg) glyptodont ''[[Neosclerocalyptus]],''<ref name="Quiñones2">{{Cite journal |last1=Quiñones |first1=Sofía I. |last2=De los Reyes |first2=Martin |last3=Zurita |first3=Alfredo E. |last4=Cuadrelli |first4=Francisco |last5=Miño-Boilini |first5=Ángel R. |last6=Poiré |first6=Daniel G. |date=2020-11-01 |title=Neosclerocalyptus Paula Couto (Xenarthra, Glyptodontidae) in the late Pliocene-earliest Pleistocene of the Pampean region (Argentina): Its contribution to the understanding of evolutionary history of Pleistocene glyptodonts |url=https://www.sciencedirect.com/science/article/pii/S0895981120302443 |journal=Journal of South American Earth Sciences |language=en |volume=103 |pages=102701 |bibcode=2020JSAES.10302701Q |doi=10.1016/j.jsames.2020.102701 |issn=0895-9811 |s2cid=225024450}}</ref> the armadillo ''[[Eutatus]]'', and the gigantic (2 ton) glyptodont ''[[Doedicurus]]'', the largest glyptodont known, were hunted.<ref>{{Cite journal |last1=Politis |first1=Gustavo G. |last2=Messineo |first2=Pablo G. |last3=Stafford |first3=Thomas W. |last4=Lindsey |first4=Emily L. |date=2019 |title=Campo Laborde: A Late Pleistocene giant ground sloth kill and butchering site in the Pampas |journal=Science Advances |language=en |volume=5 |issue=3 |pages=eaau4546 |bibcode=2019SciA....5.4546P |doi=10.1126/sciadv.aau4546 |issn=2375-2548 |pmc=6402857 |pmid=30854426}}</ref> The only other record of human predation from outside the Pampas was a partial carapace, found also in Venezuela, that was eviscerated by humans. The discoveries in the localities in Falcón showed the first signs of human hunting on the skulls of glyptodonts, but ''Glyptotherium'' also was more defenseless than glyptodonts like ''Doedicurus''.<ref name=":42" /><ref>{{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 |bibcode=2021NatCo..12.2175P |doi=10.1038/s41467-021-22506-4 |issn=2041-1723 |pmc=8041891 |pmid=33846353}}</ref>

== Distribution ==
''Glyptotherium'' is the only known North American glyptodont and is known from several regions of the continent from different periods. During the [[Blancan]] stage of the [[Pliocene|Early Pliocene]], ''Glyptotherium texanum'' inhabited only central Mexico based on the discovery of a single osteoderm of ''Glyptotherium texanum'' from the [[Zanclean|early]] [[Pliocene]] strata of [[Guanajuato]], central Mexico, dating to approx. 3.6 million years ago.<ref name=":110" /><ref name=":2">{{Cite journal |last1=Albright |first1=L. |last2=Sanders |first2=Albert |last3=Weems |first3=Robert |last4=Cicimurri |first4=David |last5=Knight |first5=James |date=2019-10-31 |title=Cenozoic vertebrate biostratigraphy of South Carolina, U.S.A., and additions to the fauna |url=https://flmnhbulletin.com/index.php/flmnh/article/view/flmnh-vol57-no2 |journal=Bulletin of the Florida Museum of Natural History |language=en |volume=57 |issue=2 |pages=77–236 |doi=10.58782/flmnh.qqgg4577 |issn=2373-9991|doi-access=free }}</ref> In the Blancan-[[Irvingtonian]] stages of the [[Early Pleistocene]], ''G. texanum'' fossils are known from most of Mexico as well as the U.S. states of [[Arizona]], [[Texas]], [[Oklahoma]], [[Florida]], and possibly [[South Carolina]].<ref name=":110" /><ref name=":2" /> In the [[Rancholabrean]] of the [[Late Pleistocene]], ''G. cylindricum'' evolved from ''G. texanum'' and its fossils have been unearthed from northern [[Venezuela]], eastern [[Brazil]], [[Central America]], Mexico, and the U.S. states of Texas, [[Louisiana]], Florida, and South Carolina.<ref name=":110" /><ref name=":2" /><ref>Sanders, A. E. (2002). ''Additions to the Pleistocene mammal faunas of South Carolina, North Carolina, and Georgia''. American Philosophical Society.</ref><ref name=":0" /> Fossils from ''Glyptotherium'' from the Early Pliocene have not been found in Central America, but it is likely that ''G. texanum'' inhabited the area during the [[Great American Interchange|Great American Biotic Interchange]]. Glyptodont fossils from the middle-late Irvingtonian are not known from the USA, creating a "glyptodont gap" in the US fossil record.<ref name=":110" /> However, ''Glyptotherium'' is recorded during this "pause" in Central America, suggesting a possible retraction of ''Glyptotherium'' to southern areas during glacial times.<ref name=":1" />
[[File:Glyptotherium_scute_Panama_USNM_PAL_540667.jpg|thumb|192x192px|An isolated glyptodont osteoderm from [[Panama]].]]
''Glyptotherium'' fossils have been collected from Central America in [[Guatemala]],<ref name=":112">{{Cite journal |last1=Dávila |first1=S. Lorena |last2=Stinnesbeck |first2=Sarah R. |last3=Gonzalez |first3=Silvia |last4=Lindauer |first4=Susanne |last5=Escamilla |first5=Juan |last6=Stinnesbeck |first6=Wolfgang |date=2019-09-01 |title=Guatemala's Late Pleistocene (Rancholabrean) fauna: Revision and interpretation |url=https://www.sciencedirect.com/science/article/pii/S0277379119302318 |journal=Quaternary Science Reviews |language=en |volume=219 |pages=277–296 |bibcode=2019QSRv..219..277D |doi=10.1016/j.quascirev.2019.07.011 |issn=0277-3791 |s2cid=201306819}}</ref> [[Costa Rica]],<ref name=":122">Valerio, A. L., & Laurito, C. A. (2011). [https://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0256-70242011000200008 El registro fósil de Glyptotherium floridanum (Xenarthra, Cingulata, Glyptodontidae) en el Cuaternario de Costa Rica, América Central.] ''Revista Geológica de América Central'', (45), 141-145.</ref> [[Honduras]],<ref>Jackson, D. R., & Fernandez, E. (2005). [https://www.floridamuseum.ufl.edu/wp-content/uploads/sites/35/2017/03/bulletin-jacksonlowres.pdf A small Pleistocene mammalian megafauna from southern Honduras.] ''Bulletin of the Florida Museum of Natural History'', ''45''(4), 261-269.</ref> [[El Salvador]],<ref>Cisneros, J. C. (2005). [https://www.researchgate.net/profile/Juan-Cisneros-15/publication/228650581_New_Pleistocene_vertebrate_fauna_from_EI_Salvador/links/00b7d51ec74a30b1e8000000/New-Pleistocene-vertebrate-fauna-from-EI-Salvador.pdf New pleistocene vertebrate fauna from El Salvador.] ''Revista Brasileira de Paleontologia'', ''8''(3), 239-255.</ref> and [[Panama]].<ref>{{Cite journal |last=Lucas |first=Spencer G. |date=2014 |title=Late pleistocene mammals from El Hatillo, Panama |url=http://www.scielo.sa.cr/scielo.php?script=sci_abstract&pid=S0256-70242014000100007&lng=en&nrm=iso&tlng=en |journal=Revista Geológica de América Central |language=en |issue=50 |pages=139–151 |issn=0256-7024}}</ref> The fossils from Central America are usually isolated and fragmentary, with the majority being osteoderms or isolated molariforms.<ref name=":110" /><ref>{{Cite journal |last1=Valerio |first1=Ana L. |last2=Laurito |first2=César A. |date=2011 |title=El registro fósil de Glyptotherium Floridanum (Xenarthra, Cingulata, Glyptodontidae) en el Cuaternario de Costa Rica, América Central |url=http://www.scielo.sa.cr/scielo.php?script=sci_abstract&pid=S0256-70242011000200008&lng=en&nrm=iso&tlng=es |journal=Revista Geológica de América Central |language=es |issue=45 |pages=141–145 |issn=0256-7024 }}{{Dead link|date=August 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> In 2023, an associated skeleton of ''G. cylindricum'', including skull and limb elements, from Guatemala was described, the most complete specimen from the region.<ref>{{Cite journal |last1=Cuadrelli |first1=Francisco |last2=Escamilla |first2=Juan |last3=Zurita |first3=Alfredo |last4=Gillette |first4=David D. |last5=Dávila |first5=Lorena S. |date=2023-08-22 |title=Glyptotherium cylindricum (Cingulata, Glyptodontidae) from the Late Pleistocene of Guatemala: the most complete record of Glyptodontinae from Central America |url=https://www.tandfonline.com/doi/full/10.1080/03115518.2023.2242440 |journal=Alcheringa: An Australasian Journal of Palaeontology |volume=47 |issue=3 |language=en |pages=336–347 |doi=10.1080/03115518.2023.2242440 |bibcode=2023Alch...47..336C |issn=0311-5518 |s2cid=261137459}}</ref> It is most likely that the first ''Glyptotherium'' populations started in Central America during the Great American Biotic Interchange in the Late Pliocene based on their paleobiogeography.<ref name=":110" /><ref name=":142" /> ''Glyptotherium'' fossils from Central America are sometimes placed as an indeterminate species,<ref name=":132" /><ref name=":52" /> but most are placed in ''Glyptotherium cylindricum'' or its synonyms.<ref name=":112" /><ref name=":122" /> This referral is also based on the age of the fossils, as the age of ''G. texanum'' fossils are measured to range from the Pliocene to early Pleistocene while the age of ''G. cylindricum'' fossils are confined to the late Pleistocene.<ref name=":110" /><ref name=":292">{{Cite journal |last1=Ramírez-Cruz |first1=Gonzalo A. |last2=Montellano-Ballesteros |first2=Marisol |date=2014 |title=Two new glyptodont records (Mammalia: Cingulata) from the late Pleistocene of Tamaulipas and Tlaxcala, Mexico: Implications for the taxonomy of the genus Glyptotherium |url=https://bioone.org/journals/the-southwestern-naturalist/volume-59/issue-4/JKF-45.1/Two-new-glyptodont-records-Mammalia--Cingulata-from-the-late/10.1894/JKF-45.1.full |journal=The Southwestern Naturalist |volume=59 |issue=4 |pages=522–530 |doi=10.1894/JKF-45.1 |issn=0038-4909 |s2cid=85750160}}</ref>

Although commonly regarded as an exclusively North American genus,<ref name=":292" /><ref name=":52" /><ref name=":110" /> fossils of ''Glyptotherium'' from northern South America in areas like Brazil and [[Venezuela]] have been discovered.<ref name=":52" /><ref name=":42" /> The fossils from South America are usually only osteoderms or caudal rings and are sometimes indeterminate on a species level, but are most likely from ''Glyptotherium cylindricum''.<ref name=":110" /><ref name=":52" /><ref name=":42" />

== Extinction ==
The chronology of megafaunal extinctions (such as ''Glyptotherium'') in the [[Late Pleistocene extinctions]] has been disputed.<ref name=":35">{{Cite journal |last1=Faith |first1=J. Tyler |last2=Surovell |first2=Todd A. |date=2009-12-08 |title=Synchronous extinction of North America's Pleistocene mammals |journal=Proceedings of the National Academy of Sciences |language=en |volume=106 |issue=49 |pages=20641–20645 |doi=10.1073/pnas.0908153106 |doi-access=free |issn=0027-8424 |pmc=2791611 |pmid=19934040|bibcode=2009PNAS..10620641F }}</ref> In the United States, the last reliable direct radiocarbon date for ''Glyptotherium'' is 23,230 ± 490 BP, from [[Inner Space Cavern|Laubach Cave No. 3]], Texas.<ref>{{Cite journal |last=Haynes |first=Gary |date=2013-02-08 |title=Extinctions in North America's Late Glacial landscapes |url=https://www.sciencedirect.com/science/article/pii/S104061821000296X |journal=Quaternary International |series=Peopling the last new worlds: the first colonisation of Sahul and the Americas |volume=285 |pages=89–98 |doi=10.1016/j.quaint.2010.07.026 |bibcode=2013QuInt.285...89H |issn=1040-6182}}</ref><ref name=":35" /> ''Glyptotherium'' groups together with ''Eremotherium'', ''Holmesina'', and ''Paramylodon'' as having reliable final dates before the end of the [[Last Glacial Maximum]] of North America.<ref>{{Cite journal |last=Stuart |first=Anthony John |date=May 2015 |title=Late Quaternary megafaunal extinctions on the continents: a short review |url=https://onlinelibrary.wiley.com/doi/10.1002/gj.2633 |journal=Geological Journal |language=en |volume=50 |issue=3 |pages=338–363 |doi=10.1002/gj.2633 |bibcode=2015GeolJ..50..338S |s2cid=128868400 |issn=0072-1050}}</ref> However, statistical analyses suggest that a later survival until the terminal Pleistocene of the United States is possible, based on sampling biases associated with uncommon fauna, and a lack of reliable dates from the humid [[Atlantic Plain|Atlantic plain]] due to poor preservation.<ref name=":35" />

In South America, burnt ''Glyptotherium'' remains have been imprecisely dated to between 16,375 ± 400 BP and 14,300 ± 500 radiocarbon BP at Muaco, Venezuela,<ref name=":42" /> with similar techniques dating the a ''Glyptotherium'' specimen from [[Taima-Taima]] to 12,580 ± 60 radiocarbon BP,<ref>{{Cite journal |last1=Carlini |first1=A.A. |last2=Zurita |first2=A.E. |date=2006 |title=Glyptotherium Osborn (Mammalia, Xenarthra, Cingulata) en el Pleistoceno Tardío de Venezuela |journal=9° Congreso Argentino de Paleontología y Bioestratigrafía, Córdoba |pages=98}}</ref><ref>{{Cite journal |last1=Faria |first1=Fabio Henrique Cortes |last2=Kinoshita |first2=Angela |last3=Carvalho |first3=Ismar de Souza |last4=Araújo-Júnior |first4=Hermínio Ismael de |last5=Pegorin |first5=Priscila |last6=Maria G Figueiredo |first6=Ana |last7=Baffa |first7=Oswaldo |date=2020-08-01 |title=ESR dating of late Quaternary megafauna fossils from João Dourado, Bahia, Brazil |url=https://www.sciencedirect.com/science/article/pii/S0895981120300997 |journal=Journal of South American Earth Sciences |volume=101 |pages=102586 |doi=10.1016/j.jsames.2020.102586 |bibcode=2020JSAES.10102586F |s2cid=216519652 |issn=0895-9811}}</ref> although a minimum date of the entire assemblage (~15,780 cal. BP, 12,980 ± 85 radiocarbon BP) is more recent.<ref name=":42" /> As with other extinct Pleistocene megafauna, potential causes of extinction include human hunting, and climate change associated with the [[Younger Dryas|Younger Dryas cold interval]].<ref name=":35" />

== See also ==
{{Portal|Paleontology|Prehistoric mammals}}
{{Commons category|Glyptotherium}}
* [[Peltephilidae]]
* [[Pleistocene megafauna]]

== References ==
{{Reflist}}{{Cingulata Genera|C.|state=autocollapse}}
{{Taxonbar|from=Q138952}}

[[Category:Prehistoric cingulates]]
[[Category:Prehistoric placental genera]]
[[Category:Pliocene mammals of North America]]
[[Category:Pleistocene xenarthrans]]
[[Category:Pleistocene mammals of North America]]
[[Category:Zanclean first appearances]]
[[Category:Holocene extinctions]]
[[Category:Blancan]]
[[Category:Irvingtonian]]
[[Category:Lujanian]]
[[Category:Rancholabrean]]
[[Category:Pleistocene Brazil]]
[[Category:Holocene Brazil]]
[[Category:Fossils of Brazil]]
[[Category:Pleistocene Costa Rica]]
[[Category:Fossils of Costa Rica]]
[[Category:Pleistocene El Salvador]]
[[Category:Fossils of El Salvador]]
[[Category:Pleistocene Mexico]]
[[Category:Fossils of Mexico]]
[[Category:Pleistocene Panama]]
[[Category:Fossils of Panama]]
[[Category:Neogene United States]]
[[Category:Pleistocene United States]]
[[Category:Fossils of the United States]]
[[Category:Pleistocene mammals of South America]]
[[Category:Pleistocene Venezuela]]
[[Category:Fossils of Venezuela]]
[[Category:Fossil taxa described in 1903]]
[[Category:Taxa named by Henry Fairfield Osborn]]

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Module:Footnotes (view source) (template editor protected)
Module:Footnotes/anchor id list (view source) (template editor protected)
Module:Footnotes/anchor id list/data (view source) (template editor protected)
Module:Footnotes/whitelist (view source) (template editor protected)
Module:Format link (view source) (template editor protected)
Module:GetParameters (view source) (protected)
Module:Hatnote (view source) (template editor protected)
Module:Hatnote/styles.css (view source) (template editor protected)
Module:Hatnote list (view source) (template editor protected)
Module:InfoboxImage (view source) (template editor protected)
Module:Italic title (view source) (template editor protected)
Module:MultiReplace (view source) (template editor protected)
Module:Multiple image (view source) (template editor protected)
Module:Namespace detect/config (view source) (protected)
Module:Namespace detect/data (view source) (protected)
Module:Navbar (view source) (protected)
Module:Navbar/configuration (view source) (protected)
Module:Navbar/styles.css (view source) (protected)
Module:Navbox (view source) (template editor protected)
Module:Navbox/configuration (view source) (template editor protected)
Module:Navbox/styles.css (view source) (template editor protected)
Module:Navbox with collapsible groups (view source) (template editor protected)
Module:Navbox with collapsible groups/configuration (view source) (template editor protected)
Module:Pagetype (view source) (protected)
Module:Pagetype/config (view source) (protected)
Module:Pagetype/disambiguation (view source) (protected)
Module:Pagetype/rfd (view source) (protected)
Module:Pagetype/setindex (view source) (protected)
Module:Pagetype/softredirect (view source) (protected)
Module:Portal (view source) (protected)
Module:Portal/images/p (view source) (template editor protected)
Module:Portal/styles.css (view source) (protected)
Module:ResolveEntityId (view source) (template editor protected)
Module:SDcat (view source) (protected)
Module:Side box (view source) (template editor protected)
Module:Side box/styles.css (view source) (template editor protected)
Module:String (view source) (protected)
Module:String2 (view source) (template editor protected)
Module:TableTools (view source) (protected)
Module:TaxonItalics (view source) (template editor protected)
Module:Taxonbar (view source) (template editor protected)
Module:Taxonbar/candidate (view source) (template editor protected)
Module:Taxonbar/conf (view source) (template editor protected)
Module:Taxonbar/exists (view source) (template editor protected)
Module:Taxonbar/whitelist (view source) (template editor protected)
Module:Template redirect regex (view source) (template editor protected)
Module:Unsubst (view source) (protected)
Module:WikidataIB (view source) (template editor protected)
Module:WikidataIB/nolinks (view source) (template editor protected)
Module:WikidataIB/titleformats (view source) (template editor protected)
Module:Wikitext Parsing (view source) (protected)
Module:Yesno (view source) (protected)

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