Glyptodon (; ) is a genus of glyptodont, an extinct group of large, herbivorous armadillos that lived from the Pliocene, around 3.2 million years ago, to the early Holocene, around 11,000 years ago, in South America. It is one of, if not the, best-known genera of glyptodont. Glyptodon has a long and storied past, being the first named extinct cingulate and the type genus of the subfamily Glyptodontinae. Fossils of Glyptodon have been recorded as early as 1814 from Pleistocene aged deposits from Uruguay, though many were incorrectly referred to the ground sloth Megatherium by early paleontologists.
The type species, G. clavipes, was described in 1839 by notable British paleontologist Sir Richard Owen. Later in the 19th century, dozens of complete skeletons were unearthed from localities and described by paleontologists such as Florentino Ameghino and Hermann Burmeister. During this era, many species of Glyptodon were dubbed, some of them based on fragmentary or isolated remains. Fossils from North America were also assigned to Glyptodon, but all of them have since been placed in the closely related genus Glyptotherium. It was not until the later end of the 1900s and 21st century that full review of the genus came about, restricting Glyptodon to just five species under one genus.
Glyptodonts were typically large, quadrupedal (four-legged), herbivorous armadillos with armored carapaces (top shell) that were made of hundreds of interconnected osteoderms (structures in dermis composed of bone). Other pieces of armor covered the tails and skull roofs, the skull being tall with hypsodont (high-crowned) teeth. As for the postcranial anatomy, pelves 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 phylogenetically 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 notoungulates and ground sloths reaching immense sizes. Glyptodon had a mixed diet of grasses and other plants, instead living at the edge forests and grasslands where the shrubbery was lower. Glyptodon had a wide muzzle, an adaptation for bulk feeding. The armor could have protected the animal from predators, of which many coexisted with Glyptodon, including the "saber-tooth cat" Smilodon, the large canid 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 Paleoindians suggests that humans may have been a causal factor in the extinctions.
History
Early history
The history and taxonomy of Glyptodon is storied and convoluted. Between 1752 and 1756, British missionary Thomas Falkner was the first to record the discovery of glyptodonts, a carapace found in the Carcaraña River in what is now Santa Fe, Argentina. The indigenous writer Garcilaso de la Vega Inga hypothesized that they came from a giant human who was "destroyed by God for the crime of sodomy". However, Falkner stated that they belonged to a giant armadillo, which would prove to be accurate. In 1814, Uruguayan priest, scientist, soldier, and later politician Dámaso Antonio Larrañaga wrote about the discovery of several unusual fossils in his Diario de Historia Natural. This work 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. The glyptodont fossils included of a femur (thighbone), carapace (shell) fragments, and a caudal tube (an armored tail covering) that he collected from a Pleistocene-aged (ca. 2.5-0.011 mya) deposit on the banks of the Solís Grande Creek in southern Uruguay. Larrañaga identified the fossils as those of Dasypus (Megatherium), believing that Megatherium was a subgenus of Dasypus because the osteoderms were found associated with a specimen of Megatherium. This misled other paleontologists to believe that Megatherium was an armored giant sloth, an idea followed by French paleontologist Georges Cuvier. Cuvier went on to describe Megatherium in 1796, which sparked a new wave of European colonial and scientific interest in South America. In this period, South America's rich natural history, especially its fossils, were plundered and sold to European scientists and institutions. Often, these fossils were mixed together, had vague locality information, and were damaged because of poor packing. 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. Larrañaga also noted that similar fossils had been found in "analogous strata near Lake Mirrim, on the frontier of the Portuguese colonies" (southern Brazil).
In the 1820s, Prussian explorer Friedrich Sellow discovered a host of glyptodont fossils in two different locales; a femur and caudal tube (an armored tail covering known in glyptodonts) from the Queguay Grande River in northern Uruguay, and a carapace from the Arapey Grande River.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. In 1827, German mineralogist Christian Samuel Weiss regarded the carapace as coming from Megatherium as well, while the caudal tube was stated to be a palm tree trunk. Weiss and other paleontologists noted that the osteoderms closely resembled those of armadillos, but Cuvier's hypothesis was popularized based on the incorrect referral of glyptodontine osteoderms to Megatherium. British naturalist William Clift backed this view in 1835 when describing some glyptodont fossils from the Salado River, stating they came from Megatherium. In 1831, French paleontologist Geoffroy Saint-Hilaire informally named some osteoderms discovered by Sellow as coming from a Teleosaurus-like reptile, which he dubbed lepitherium.
However, an 1833 paper by German scientist Eduard Joseph d'Alton argued that Sellow's fossils came from an armadillo, not Megatherium. Here, d'Alton he described more of the material sent by Sellow, including portions of the limbs, manus (hands), and shoulder girdle. These he compared to Dasypus and Chlamyphorus, leading him to conclude that the fossils unearthed by Sellow came from a close relative of living armadillos rather than Megatherium. In 1836, this hypothesis was supported by French naturalist Charles Léopold Laurillard, 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. The modern consensus is that many of the osteoderms, carapaces, and caudal tubes mistakenly assigned to Megatherium come from Glyptodon instead. In 1837, Danish paleontologist Peter Wilhelm Lund was the first to scientifically describe a glyptodont, Hoplophorus, based on osteoderms, teeth, skull bones, and other fossils found in Lagoa Santa, Brazil. Following the discovery of Hoplophorus, a multitude of other glyptodont genera were named, such as Chlamydotherium and Orycterotherium in 1838, and Pachypus in 1839. In December 1838, Uruguayan naturalist Teodoro Vilardebó and politician Bernardo Berro discovered a well preserved Glyptodon skeleton in the Arroyo del Pedernal Grande, Uruguay. Between December 9 and 14, the skeleton was unearthed while between March 31 and April 5 it was described in a series of newspaper articles. In their last installment, they named the new species Dasypus antiquus, making it the first species name formally assigned to Glyptodon. Although the valid name for Glyptodon, this discovery received little recognition because of a language barrier between South American and European scientific journals. Furthermore, European scientists, especially the British, had their own desire to take taxonomic priority over Glyptodon before it was named.
Glyptodon clavipes
One of several European fossil traders who unearthed Glyptodon remains and/or sold them to European museums and collections was British diplomat Sir Woodbine Parish. He worked with a web of fossil traders to procure fossils from Argentine and Uruguayan locales and sell them back to European institutions.Parish, W. (1852). Buenos Ayres, and the provinces of the Rio de La Plata: their present state, trade, and debt. Murray. At the same time as Parish's discoveries, British naturalist Charles Darwin was on the second voyage of the HMS Beagle, wherein he discovered several Megatherium and Glyptodon fossils in southern South America. Once these fossils made it to the RC, it was soon recognized that the carapaces and osteoderms ascribed to Megatherium by earlier authors derived from their own taxon. In 1838, Parish received an isolated molariform (cheek tooth) attached to a letter containing information on the discovery of several large 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. That same year, British paleontologist Sir Richard Owen informally named Glyptodon based on the tooth, but did not provide a species name. In 1839, Owen informally mentioned and illustrated Glyptodon in a chapter of Parish's book Buenos Ayres, and the Provinces of the Rio de La Plata: their present state, trade, and debt.Owen, R. (1839). Note on the Glyptodon. Buenos Aires and the Provinces of the Rio de La Plata, 1-178.
Owen was working with material from three different localities. This included a mandible (lower jaw) fragment, incomplete left forelimb, a partial right hindlimb, and pieces of the right pes, which were found at Villanueva, the molariform, which was found in Matanza, and portions of a carapace from Las Averías.Hoffstetter, R. (1955). Sur le genotype de Glyptodon Owen. Bulletin du Muséum National d'Historie Naturelle, 27(5), 408-413. These fossils were deposited in Parish's collection at the Royal College of Surgeons (RC) upon his return to the United Kingdom earlier in the 1830s. In both Parish's book and his subsequent formal description, Owen erroneously believed the fossils were all from the same specimen. In 1839, Owen formally described the new genus and species Glyptodon clavipes. The generic name Glyptodon derives . This is in reference to the sculpted anatomy of the molariform. The specific epithet clavipes is derived from the Latin: clava, which can mean "club" or "knotted staff"; and pes, meaning "of or pertaining to a foot". Several remains were cast at the Natural History Museum, London, but the original fossils were lost after German aerial bombing raids hit the college during World War II between 1940 to 1941.