Glyptodon (; )
The type species, G. clavipes, was described in 1839 by notable British Paleontology Richard Owen. Later in the 19th century, dozens of complete skeletons were unearthed from localities and described by paleontologists such as Florentino Ameghino and Hermann Burmeister. During this era, many species of Glyptodon were dubbed, some of them based on fragmentary or isolated remains. Fossils from North America were also assigned to Glyptodon, but all of them have since been placed in the closely related genus Glyptotherium. It was not until the later end of the 1900s and 21st century that full review of the genus came about, restricting Glyptodon to just five species under one genus.
Glyptodonts were typically large, quadrupedal (four-legged), Herbivore armadillos with armored (top shell) that were made of hundreds of interconnected (structures in dermis composed of bone). Other pieces of armor covered the tails and , the skull being tall with hypsodont (high-crowned) teeth. As for the postcranial anatomy, Pelvis fused to the carapace, an amalgamate vertebral column, short limbs, and small digits are found in glyptodontines. Glyptodon reached up to 2 meters (6.56 feet) long and 400 kilograms (880 pounds) in weight, making it one of the largest glyptodontines known. Glyptodon is morphologically and Phylogenetics most similar to Glyptotherium, however they differ in several ways. Glyptodon is larger on average, with an elongated carapace, a relatively shorter tail, and a robust zygoma, or cheek bone.
Glyptodonts existed for millions of years, though Glyptodon itself was one of its last surviving members. Glyptodon was one of many South American megafauna, with many native groups such as Notoungulata and ground sloths reaching immense sizes. Glyptodon had a mixed diet of grasses and other plants, instead living at the edge forests and grasslands where the shrubbery was lower. Glyptodon had a wide muzzle, an adaptation for bulk feeding. The armor could have protected the animal from predators, of which many coexisted with Glyptodon, including the "saber-tooth cat" Smilodon, the large Canidae Protocyon, and the giant bear Arctotherium.
Glyptodon, along with all other glyptodonts, became extinct at the end of the Late Pleistocene, around 12,000 years ago as part of the Late Pleistocene extinctions, along with most large mammals in the Americas. Evidence of hunting of glyptodonts by recently arrived Paleo-Indians suggests that humans may have been a causal factor in the extinctions.
History
Confusion with Megatherium
The history and taxonomy of
Glyptodon is storied and convoluted, as it involved confusion with other genera and
Nomen dubium species, as well as a lack of detailed data. The first recorded discovery of
Glyptodon was as early as 1814 when Uruguayan priest, scientist, soldier, and later politician Dámaso Antonio Larrañaga (1771–1848) wrote about the discovery of several unusual fossils in his
Diario de Historia Natural, which included his descriptions of many new species of ants, birds, mammals, and even one of the first figures of the extinct
Megatherium, a genus of giant
ground sloth that was named in 1796 by French scientist
Georges Cuvier (1769–1832).
[Cuvier, G. (1796). Notice sur le squelette d'une très-grande espèce de quadrupède inconnue jusqu'à présent, trouvé au Paraguay, et déposé au cabinet d'histoire naturelle de Madrid. de l'imprimerie du Magasin encyclopédique, rue Honoré No 94, vis-à-vis le passage Roch.] This was the first recorded discovery of a
or fossil
Cingulata.
The unusual fossils consisted of a femur,
carapace fragments, and a caudal tube (an armored tail covering found in glyptodontines) that he collected from the
Pleistocene aged (ca. 2.5-0.011 mya) strata on the banks of the Solís Grande Creek, Uruguay.
Larrañaga identified the fossils as those of
Dasypus (
Megatherium), believing that
Megatherium was a subgenus of
Dasypus based on the incorrect referral of glyptodontine osteoderms to
Megatherium years earlier by Spanish scientist Juan Bautista Bru de Ramón, which misled other scientists to believe that glyptodontine fossils were actually those of armored megatheres.
Larrañaga wrote to French scientist Auguste Saint Hilaire about the discovery, and an extract from the letter was reproduced by Cuvier in 1823 in the eighth volume of his landmark book Recherches sur les ossemens fossiles.[Weiss, C. S. (1830). "Über das südliche Ende des Gebirgszuges von Brasilien in der Provinz S. Pedro do Sul und der Banda oriental oder dem Staate von Monte Video. Nach den Sammlungen des Herrn Fr. Sellow (Gelesen in der Akademie der Wissenschaften am 9. August 1827 und 5. Juni 1828)". Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin.] The femur and caudal armor were recovered from the Queguay in northern Uruguay, while the carapace had been found in the Arapey River.
Another work on the armored Megatherium hypothesis was published in 1833 by the German scientist Eduard Joseph d'Alton, who described more of the material sent by Sellow, including portions of the limbs, manus, and shoulder girdle. D'Alton recognized the great similarities of the fossils to Dasypus and speculated that it was a giant armadillo, contrary to the notion that they were from Megatherium. Despite this, D'Alton did not erect a new name for the fossils and instead wrote that additional material was necessary to distinguish it from other armadillos. D'Alton did not mention Megatherium or its osteoderms in the paper, but he implied that all of the " Megatherium armor" was instead from his armadillo. This hypothesis was supported by Charles Léopold Laurillard in 1836, who mentioned that a plaster cast of a large armadillo carapace represented a distinct taxon from Megatherium and that the armor referred to the sloth was instead from an armadillo.
1837 saw the naming of the first glyptodontine, Hoplophorus euphractus, when Danish paleontologist Peter Wilhelm Lund published a series of memoirs on the fossils of Lagoa Santa in Brazil, dating to the Pleistocene.[Lund, P. W. (1837). Blik paa brasiliens dyreverden för sidste jordomvaeltning. Popp.][Bronn, H. G. (1858). Untersuchungen über die Entwickelungs-Gesetze der organischen Welt während der Bildungs-Zeit unserer Erd-Oberfläche. E. Schweizerbart.] Pachypus by Eduard D'Alton in 1839,[Saint-Hilaire, E. G. (1831). Recherches sur de grands sauriens: trouvés à l'état fossile vers les confins maritimes de la basse normandie, attribués d'abord au crocodile, puis déterminés sous les noms de téléosaurus et sténéosaurus. Firmin Didot.] Saint-Hilaire considered the osteoderms found by Sellow to not even be mammal, but instead of a relative of Teleosaurus, a crocodile-like reptile known from Jurassic deposits in France.
Richard Owen and referred species
In 1838, British diplomat
Woodbine Parish (1796–1882) was sent an isolated molariform attached to a letter about the discovery of several large, Pleistocene-aged fossils from the
Matanza River in Buenos Aires, Argentina.
[Owen, R. (1841). VI.—Description of a Tooth and Part of the Skeleton of the Glyptodon clavipes, a large Quadruped of the Edentate Order, to which belongs the Tesselated Bony Armour described and figured by Mr. Clift in the former Volume of the Transactions of the Geological Society; with a consideration of the question whether the Megatherium possessed an analogous Dermal Armour. Transactions of the Geological Society of London, 6(1), 81-106.] Parish later collected several more fossils from localities in Las Averias and Villanueva; the latter including a partial skeleton containing a mandible fragment and a set of partial limbs. This skeleton was deposited in Parish's collection at the Royal College of Surgeons upon his return to the United Kingdom.
[ Some of these fossils were cast at the Natural History Museum, London, but the original fossils were destroyed after The Blitz hit the college during World War II from 1940 to 1941. In 1839, Glyptodon was named by Richard Owen (1804–1892) in a chapter of the book Buenos Ayres, and the Provinces of the Rio de La Plata: their present state, trade, and debt.][Parish, W. (1852). Buenos Ayres, and the provinces of the Rio de La Plata: their present state, trade, and debt. Murray.][Owen, R. (1839). Note on the Glyptodon. Buenos Aires and the Provinces of the Rio de La Plata, 1-178.] Within this book, Owen erroneously believed the fossils from Las Averias and Villanueva were all from the same specimen, which he named Glyptodon ("grooved tooth") based on the anatomy of the molariform.[Hoffstetter, R. (1955). Sur le genotype de Glyptodon Owen. Bulletin du Muséum National d'Historie Naturelle, 27(5), 408-413.] However, the lectotype of G. clavipes was undiagnostic and indistinguishable from other Glyptodon species and even Glyptotherium, making it dubious.
Cuadrelli et al (2018) designated the species a species inquirenda due to this issue and commented that more analyses are necessary.
Later in 1845, many more fossils found by Parish from Pleistocene layers in Argentina were named as new species of Glyptodon by Owen: G. ornatus, G. reticulatus, G. tuberculatus, and G. clavicaudatus in 1847. Of these additional species, only G. reticulatus is still considered a valid species of Glyptodon as G. ornatus was reassigned to the genus Neosclerocalyptus,[Paula Couto, C. D. (1957). Sôbre um gliptodonte do Brasil. Boletim Divisão de Geologia e Mineralogia, 165, 1-37.] G. tuberculatus to Panochthus,[Burmeister, G. (1866). Lista de los mamíferos fósiles del terreno diluviano. In Anales del Museo Público de Buenos Aires (Vol. 1, No. 3, pp. 121-232).] and G. clavicaudatus to Doedicurus.[Burmeister, G. Burmeister 1870–1874. Monografia de los glyptodontes en el Museo Público de Buenos Aires. Anales del Museo Público de Buenos Aires, 2, 1-412.] G. reticulatus was named on the basis of several carapace fragments that had also been recovered from the Matanza River, but they lack detailed locality information and the fossils too were destroyed during WWII. The fragments were cast by the NHMUK as well, being used to diagnose the species.
Other paleontologists also started erecting names for Glyptodon species after the 1840s, but many of them are now seen as dubious, species inquirenda, or synonymous with previously named species.[Nodot, L. (1856). Description d'un nouveau genre d'édenté fossile renfermant plusieurs espèces voisines du glyptodon: suivie d'une nouvelle méthode de classification applicable à toute l'histoire naturelle, et spécialement à ces animaux, avec un atlas de douze planches lithographiées; ouvrage publié par l'Académie des sciences, arts et belles-lettres de Dijon et l'atlas avec le concours du Conseil municipal de même ville. Imprimerie Loireau-Feuchot.] Another species now seen as valid, G. munizi, was described in 1881 by Argentine paleontologist Florentino Ameghino (1853–1911) on the basis of several osteoderms found in the Ensenadan of Arroyo del Medio, San Nicolás, Argentina.[Ameghino, F. 1882. Catálogo de las colecciones de Antropología prehistórica y paleontología de Florentino Ameghino, Partido de Mercedes. En: Catálogo de la Sección de la Provincia de Buenos Aires (República Argentina). Exposición Continental Sudamericana. Anexo A: 35-42.] For many years the taxon was only known from the fragmentary holotype, but skull and complete carapace material of the species was later described in detail in 2006 that cemented its validity.[Burmeister, H. (1866). XXXIX.—On Glyptodon and its allies. Annals and Magazine of Natural History, 18(106), 299-304.][Castellanos, A. (1932). Nuevos géneros de gliptodontes en relación con su filogenia.][Castellanos, A. (1953). Descripción de restos de" Paraglyptodon uquiensis" n. sp. de Uquía (Senador Pérez) de Jujuy (No. 32). la Provincia.] The former species is dubious, but likely not Glyptodon based on its age.
Reassessment and Glyptotherium
In the 1950s, Argentine paleontologist Alfredo Castellanos (1893–1975) erected new generic names for several species of Glyptodon, the first being Glyptocoileus and second of these being Glyptopedius in 1953 that was made for the species G. elongatus that had been named by Robert Burmeister in 1866 on the basis of a single carapace,
Another Glyptodon species was described in 2020 called G. jatunkhirkhi by several authors led by Argentine zoologist Francisco Cuadrelli on the basis of an individual preserving a nearly complete carapace, several caudal rings, and a pelvis that had been collected from Yamparaez, southeast of the Bolivian city of Sucre. The strata they were found in was made up of fluvial, sandy sediments that dated to the Late Pleistocene from elevations as high as above sea level.
Fossils from North America were also described and referred to Glyptodon starting in 1875, when civil engineers J. N. Cuatáparo and Santiago Ramírez collected a skull, nearly complete carapace, and associated postcranial skeleton of a glyptodontine from a drainage canal near Tequixquiac, Mexico, the fossils coming from the Rancholabrean of the Pleistocene.[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.]
Taxonomy
Glyptodon is the type genus of Glyptodontinae, an extinct subfamily of large, heavily armored armadillos that first evolved in the Eocene (ca. 33.5 mya) and went extinct in the Greenlandian during the Late Pleistocene extinctions (ca. 7,000 years ago).[Gray, J. E. (1869). Catalogue of carnivorous, pachydermatous, and edentate Mammalia in the British Museum. order of the Trustees.] However, Hermann Burmeister proposed the name Biloricata for the family, believing that glyptodontines possessed a ventral Turtle shell (bottom shell) and could pull their heads inside their carapaces like turtles. This name lost all use and his theory has not been supported.[Ameghino, F. (1889). Contribucion al conocimiento de los mamiferos fosiles de la República Argentina: Obra escrita bajo los auspicios de la Academia nacional de ciencias de la República Argentina para ser presentada á la Exposicion universal de Paris de 1889 (Vol. 6). PE Coni é hijos.]
Glyptodontinae was classified in its own family or even superfamily until in 2016, when ancient DNA was extracted from the carapace of a 12,000 year old Doedicurus specimen, and a nearly complete mitochondrial genome was reconstructed (76x coverage). Comparisons with those of modern armadillos revealed that glyptodonts diverged from Tolypeutinae and Chlamyphorinae armadillos approximately 34 million years ago in the Priabonian.
The internal phylogeny of Glyptodontinae is convoluted and in flux, with many species and families erected based on fragmentary or undiagnostic material that lacks comprehensive review.[Oliveira, É. V., Porpino, K. D., & Baretto, A. (2010). On the presence of Glyptotherium in the Late Pleistocene of Northeastern Brazil, and the status of " Glyptodon" and " Chlamydotherium". Paleobiogeographic implications. Neues Jahrbuch fur Geologie und Palaontologie-Abhandlungen, 258(3), 353.][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.][Cope, E. D. (1889). the edentata of North America. The American Naturalist, 23(272), 657-664.]
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:
Description
Like the extant armadillos and all other glyptodontines, Glyptodon had a large, bony carapace that covered much of its torso, as well as smaller Head armor covering the roof of its head, akin to that in turtles. The carapace was composed of hundreds of small, hexagonal osteoderms (armored structures made of bone), with Glyptodon carapaces preserving a total of 1,800 osteoderms each. The anatomy of different Glyptodon species varies greatly, mostly in the species G. jatunkhirkhi which is more similar to Glyptotherium in certain aspects.
In the axial skeleton, glyptodontines had strongly fused and Pelvis completely connected to the carapace, traits convergently evolved in turtles.
During the Pleistocene, the diversity of glyptodontines diminished but body size increased, with the largest known glyptodont, Doedicurus, evolving in the Pleistocene.[Fariña, R. A., Vizcaíno, S. F., & Bargo, M. S. (1998). Body mass estimations in Lujanian (late Pleistocene-early Holocene of South America) mammal megafauna. Mastozoología Neotropical, 5(2), 87-108.]
Skull, mandible, and dentition
Glyptodont dentition contains entirely hypsodont molariforms, which have one of the most extreme examples of hypsodonty known from terrestrial mammals. The dentition is typical of other armadillos, but is fluted on each side by deep grooves. The anterior teeth were compressed, while the posterior teeth were cylindrical.[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.]
The nasal passage was reduced with heavy muscle attachments for some unknown purpose. Some have speculated that the muscle attachments were for a proboscis, or Torso, much like that of a tapir or elephant. The lower jaws were very deep and helped support massive chewing muscles to help chew coarse fibrous plants. Some paleontologists have proposed that Glyptodon and some glyptodontines also had a proboscis or large snout similar to those in and , but few have accepted this hypothesis.
Vertebrae and pelvis
Glyptodon has 7 cervical vertebrae, of which the first 3 cervicals were fused together while the rest of the cervicals were free except for the 7th.
Carapace and osteoderms
|alt=A Glyptodon carapace.]] Glyptodons osteoderms were attached by Synostosis (bony connections) and were found in double or triple rows on the front and sides of the carapace's edges, as well as in the tail armor and cephalic shield. The carapace's osteoderms were conical with a rounded point, while the ones on the tail were just Cone. The sulci between these raised structures were deep and wide with parallel lines.
Osteoderms on the ventral side of the body were first mentioned by paleontologist Hermann Burmeister in 1866, postulating that there was a ventral plastron like in turtles based on evidence of small armor in the dermis.
Tail
Glyptodon had very primitive tail anatomy for a glyptodont, possessing eight or nine mobile caudal rings of fused, large, conical osteoderms. These enclosed the base of the tail, which terminated in a short caudal tube composed of two fused caudal rings. Caudal rings were composed of two or three rows of pentagonal osteoderms that transitioned from flat, slightly convex in the posterior rings to conical by the third caudal ring. The more posterior the rings were, the larger they were, with the exception of the 2nd ring which was the largest and 1st complete ring in the series, creating a cone-shaped tail. The distal scutes are larger, and their free margins are rounded producing a fan-like shape. Most of the osteoderms of the distal row (some individuals preserving up to 12) bear prominent conical outlines, in stark contrast to more advanced glyptodontines like Doedicurus and Panochthus, which had completely fused tails that formed an inflexible mace or club.
Paleobiology
Digging abilities
Many armadillo species have digging capabilities, with large claws adapted for scraping dirt in order to make burrows or forage for food underground.[Vizcaíno, S. F., Fariña, R. A., & Mazzetta, G. V. (1999). Ulnar dimensions and fossoriality in armadillos. Acta Theriologica, 44.][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.] Much of armadillo diets consist of insects and other invertebrates that live underground,
Endocranial anatomy
Several complete skulls of Glyptodon enable the endocranial anatomy to be analyzed, as well as compared to other well-preserved taxa like Doedicurus and Panochthus. The brain cavities of the larger glyptodontines Glyptodon, Doedicurus, and Panochthus had a braincase volume of . The encephalization quotient of these taxa are 0.12 to 0.4, lower than most modern armadillos (0.44-1.06) and corresponds to those of pampatheres. The brain of the glyptodontines had an extensive olfactory bulb that took up between 4.8 and 9.7% of the entire brain, while around two thirds of it were occupied by the cerebrum and the rest by the cerebellum. Overall, this is akin to that of other armadillos, but in the latter the cerebrum is smaller relative to the cerebellum and the braincase's total volume. Deviating from the armadillos with their wide olfactory bulb, glyptodontines and pampatheres have elongated and triangular olfactory systems. Several other neuroanatomical characteristics differ between glyptodontines and armadillos, such as the presence of a pronounced sulcus praesylvianus.
In general, living cingulates have smaller brains than anteaters and sloths for reasons unknown. Several theories have been made as to why, such as a shorter rearing phase of offspring, dedication of resources to the development of the carapace, and other biological and functional handicaps. Members of Cingulata also tend to have extremely low metabolisms, causing less energy flow to the development of the brain's neurons. The pattern of large bodies bearing adequate protection and a reduction of intelligence is found in several other groups such as Ankylosauria and Stegosauria, two types of armored dinosaur. However, the carapace itself is considered as a restrictive functional component as it prohibited much neck movement and forced a reduced brain size. This reduction thus resulted in weight loss in the skull, which had a great effect on the skulls of large-headed glyptodontines like Glyptodon.
Feeding and diet
Two main groups of glyptodontines can be distinguished by their feeding habits: narrow-muzzled Miocene propalaehoplophorids and wide-muzzled post-Miocene glyptodontines.[Zamorano, M., Scillato-Yané, G. J., Soibelzon, E., Soibelzon, L. H., Bonini, R., & Rodriguez, S. (2018). Hyoid apparatus of Panochthus sp.(Xenarthra; Glyptodontidae) from the Late Pleistocene of the Pampean region (Argentina). Comparative description and muscle reconstruction. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen, 288, 205-219.]
Like most other xenarthrans, glyptodontines had lower energy requirements than contemporary mammal groups.[Fariña, R.A., 1995. Limb bone strength and habits in large glyptodonts. Lethaia, 28: 189-196.] though more backing for this hypothesis has been found in the related Glyptotherium.[Pomi, L. H. (2008). Una nueva asociación de vertebrados fósiles de Edad Ensenadense (Plioceno tardío-Pleistoceno medio) de la provincia de Buenos Aires, Argentina. Ameghiniana, 45(2), 503-510.] with a mix of slightly wooded and slightly open habitats as implied by the consumption of C3 and C4 material.
Intraspecific combat
Glyptodonts are believed to have taken part in intraspecific fighting. It was presumed that since the tail of Glyptodon was very flexible and had rings of bony plates, it was used as a weapon in fights. Although its tail could be used for defense against predators, evidence suggests that the tail of Glyptodon was primarily for attacks on its own kind. A G. reticulatus fossil displays damage done on the surface of its carapace. A study based on this specimen calculated that Glyptodon tails would have been able to generate enough force to break the carapace of another Glyptodon. This suggests that they likely fought each other to settle territorial or mating disputes through the use of their tails, much like male-to-male fighting among deer using their antlers.
Ontogeny
In 2009, a partial skeleton of a prenatal individual of Glyptodon was described that had been found inside of the pelvic region of a carapace of an adult.
In the osteoderms of juvenile Glyptodon reticulatus, the central figures are larger than the peripheral osteoderms. These central figures are planar, sometimes even concave, and elevated compared to the peripherals. The peripherals in younger individuals are also less distinct and bear weakly marked or absent furrows (grooves that separate osteoderms). On the other hand, peripherals and central figures of adults are similarly sized, distinct, and of similar heights.
Posture
Several interpretations of glyptodontine posture have been made,[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.] Linear measurements were later taken which provided insight into this hypothesis, finding that bipedalism would be possible.[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.][Shockey, B. J. (2001). Specialized knee joints in some extinct, endemic, South American herbivores. Acta Palaeontologica Polonica, 46(2).]
Trackways
The first ever glyptodont footprints were recovered from the late Pleistocene Pehuén-Có fossil site, Argentina, and referred to Glyptodon. Described as the ichnotaxon Glyptodontichnus pehuencoensis in 2015, the rarity of glyptodont trackways despite their frequency in the fossil record suggests that glyptodonts may have avoided walking on muddy substrates as they'd be especially vulnerable to getting trapped.
Sexual dimorphism and group behavior
No evidence of sexual dimorphism in Glyptodon has been described, but it has been observed in the close relative Glyptotherium based on fossils found in Pliocene deposits in Arizona . In the genus, the caudal aperture 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.[Superina, M. (2000). Biologie und Haltung von Gürteltieren (Dasypodidae) (Doctoral dissertation, Uitgever niet vastgesteld).]
Distribution and paleoecology
Glyptodon is one of the most common Pleistocene glyptodontines with a large range from the lowland Pampas to the towering Andes of Peru and Bolivia, some fossils found at elevations reaching over above sea level.[Blasi, A., Castiñeira Latorre, C., Del Puerto, L., Prieto, A. R., Fucks, E., De Francesco, C., ... & Young, A. (2010). Paleoambientes de la cuenca media del río Luján (Buenos Aires, Argentina) durante el último período glacial (EIO 4-2). Latin American journal of sedimentology and basin analysis, 17(2), 85-111.][Kruck, W., Helms, F., Geyh, M. A., Suriano, J. M., Marengo, H. G., & Pereyra, F. (2011). Late pleistocene-holocene history of chaco-pampa sediments in Argentina and Paraguay. E&G Quaternary Science Journal, 60(1), 14.][Zurita, A. E., M. Taglioretti, M. De los Reyes, C. Oliva, and F. Scaglia. 2014. First Neogene skulls of Doedicurinae (Xenarthra, Glyptodontidae): morphology and phylogenetic implications. Historical Biology 28:423–432.] G. jatunkhirkhi specifically is known only from Andean climate of Eastern Cordillera in Bolivia, causing it to evolve to be smaller in size than lowland species due to less support for larger masses.
Material previously assigned to Glyptodon in northeast Brazil has been reassigned to Glyptotherium, restricting the Brazilian distribution of Glyptodon to the southern provinces. However, two osteoderms with characteristics similar to those of Glyptodon have been found in Sergipe state in the northeast, suggesting that both genera occurred in this region during the Pleistocene.
Predation and relationship with humans
Glyptodon coexisted with a variety of large predators including the cat Smilodon, , and canid Protocyon.[Montalvo, C. I., Zárate, M. A., Bargo, M. S., & Mehl, A. (2013). Registro faunístico y paleoambientes del Cuaternario tardío, provincia de La Pampa, Argentina. Ameghiniana, 50(6), 554-570.] This belief is furthered by the discovery of fractured dorsal armor, which implies that Glyptodon had been in physical conflict with other animals.
Smilodon may have occasionally preyed upon glyptodontines, based on a skull of Glyptotherium texanum which bears the distinctive elliptical puncture marks that best match those of the machairodont cat, indicating that the predator successfully bit into the skull through the armored cephalic shield.[Brandes, G. (1900) : Ueber eine Ursache des Aussterbens Diluvialer Säugethiere. Corrblatt d. Deutsch . Ges. f. Anthropol. Jahrg. 31. Munichen 1901.] Smilodon canines could not pierce the thick carapace osteoderms of glyptodontines.[Bohlin, B. (1940). 8. Food habit of the machairodonts, with special regard to Smilodon.] Brandes imagined that the evolution of thick glyptodontine armor and long machairodont canines was an example of coevolution,[Vogt, C. (1881). Squelette humain associe aux glyptodontidae. Bulletin de la Societe d'Antropologie de Paris, 3(4), 693–699] and many fossil discoveries from the Late Pleistocene to Early Holocene have been unearthed since that exhibit human predation on glyptodontines. No fossils of Glyptodon preserving direct interactions have been unearthed, but it did inhabit this region alongside humans. At the site of Pay Paso 1, an archaeological site in northwestern Uruguay preserving human-made spear points and other signs of culture were found associated with fossils of Glyptodon and the horse Equus. These were used for radiocarbon dating using collagen, supposedly dating to around 9,000 to 9,500 BP but these dates cannot be verified.[Fidalgo, F., et al. (1986) "Investigaciones arqueológicas en el sitio 2 de Arroyo Seco (Pdo. de Tres Arroyos, prov. de Buenos Aires, República Argentina)" In: Bryan, Alan (ed.) (1986) New evidence for the Pleistocene peopling of the Americas Peopling of the Americas Symposia Series, Center for the Study of Early Man, University of Maine, Orono, Maine, , pp. 221–269, in Spanish][Politis, Gustavo G. and Gutierrez, Maria A. (1998) "Gliptodontes y Cazadores-Recolectores de la Region Pampeana (Argentina)" (" Glyptodonts and Hunter-Gatherers in the Pampas Region (Argentina)") Latin American Antiquity9(2): pp.111–134 in Spanish]
Glyptodon was also a victim of parasitism, as evidenced by findings of Karethraichnus kulindros on an articulated carapace of G. clavipes, which are believed to represent traces made by tungid fleas that were related to Tunga perforans.
Extinction
Glyptodon, along with all other glyptodonts became extinct around the end of the Late Pleistocene, as part of a wave of extinctions of most large mammals across the Americas. Some evidence suggests that humans drove glyptodontines to extinction.
The extinction of Glyptodon notably coincides with the end of the Antarctic Cold Reversal period in which, for 1,700 years, temperatures dropped before spiking after ending at 12.7 ka.
See also
External links
