Biology:Megatherium

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Short description: Genus of ground sloth (extinct)

Megatherium
Temporal range: Early Pliocene[1] to Early Holocene, 5–0.010 Ma
↓
Possible later date of 0.008 Ma
Megatherium americanum Skeleton NHM.JPG
M. americanum skeleton, Natural History Museum, London
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Pilosa
Clade: †Megatheria
Family: †Megatheriidae
Subfamily: †Megatheriinae
Genus: †Megatherium
Cuvier, 1796
Type species
†Megatherium americanum
Cuvier, 1796
Subgenera
Megatherium range map.svg
Map showing the distribution of all Megatherium species in red, inferred from fossil finds
Synonyms
  • Essonodontherium Ameghino 1884
  • Orocanthus Ameghino 1885
  • Neoracanthus Ameghino 1889

Megatherium (/mɛɡəˈθɪəriəm/ meg-ə-THEER-ee-əm; from Greek méga (μέγα) 'great' + theríon (θηρίον) 'beast') is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene[1] through the end of the Pleistocene.[2] It is best known for the elephant-sized type species M. americanum, sometimes known as the giant ground sloth, or the megathere, native to the Pampas through southern Bolivia during the Pleistocene. Various other smaller species belonging to the subgenus Pseudomegatherium are known from the Andes.

Megatherium is part of the sloth family Megatheriidae, which also includes the similarly giant Eremotherium, comparable in size to M. americanum, which was native to tropical South America, Central America and North America as far north as the southern United States. Megatherium was first discovered in 1788 on the bank of the Luján River in Argentina. The holotype specimen was then shipped to Spain the following year wherein it caught the attention of the paleontologist Georges Cuvier, who was the first to determine, by means of comparative anatomy, that Megatherium was a sloth.[3] Megatherium became extinct around 12,000 years ago as part of the Late Pleistocene extinctions, simultaneously with the majority of other large mammals in the Americas. The extinctions followed the first arrival of humans in the Americas, and one and potentially multiple kill sites where M. americanum was slaughtered and butchered is known, suggesting that hunting could have caused its extinction.[4]

Taxonomy

Megatherium is divided into 2 subgenera, Megatherium and Pseudomegatherium. Taxonomy according to Pujos (2006) and De Iuliis et al (2009):[5][6]

  • Subgenus Megatherium
    • †M. altiplanicum Saint-André & de Iuliis 2001
    • †M. americanum Cuvier 1796
  • Subgenus Pseudomegatherium Kraglievich 1931
    • †M. celendinense Pujos 2006
    • †M. medinae Philippi 1893
    • †M. sundti Philippi 1893
    • †M. tarijense Gervais & Ameghino, 1880
    • †M. urbinai Pujos & Salas 2004
Specimen of M. americanum in Museo Nacional de Ciencias Naturales, Madrid, the first prehistoric animal skeleton mounted, in 1795.

The first fossil specimen of Megatherium was discovered in 1788 by Manuel Torres, on the bank of the Luján River in Argentina . The fossil was shipped to Museo Nacional de Ciencias Naturales in Madrid the following year, where it remains. It was reassembled by museum employee Juan Bautista Bru, who also drew the skeleton and some individual bones.[7]

Based on Bru's illustrations, comparative anatomist Georges Cuvier determined the relationships and appearance of Megatherium. He published his first paper on the subject in 1796, a transcript of a previous lecture at the French Academy of Sciences. He published on the subject again in 1804; this paper was republished in his book Recherches sur les ossemens fossiles de quadrupèdes.[3] In his 1796 paper, Cuvier assigned the fossil the scientific name Megatherium americanum. Cuvier determined that Megatherium was a sloth, and at first believed that it used its large claws for climbing trees, like modern sloths, although he later changed his hypothesis to support a subterranean lifestyle, with the claws used to dig tunnels.[3]

Fossils of Megatherium and other western megafauna proved popular with the Georgian-era public, preceding the discovery of giant dinosaurs some decades later.

Since the original discovery, numerous other fossil Megatherium skeletons have been discovered across South America, in Argentina , Bolivia, Brazil , Chile , Colombia (Quipile, Cundinamarca),[8][9] Guyana, Paraguay, Peru and Uruguay.[2] New species in the genus Megatherium, M. urbinai and M. celendinense, have been described in 2004 and 2006, respectively.[10] M. celedinense is named after Celendin, Cajamarca Province in the Peruvian Andes.[5] These species are considerably smaller than M. americanum, and are considered to belong to a separate subgenus, Pseudomegatherium.[5]

The species Megatherium (Pseudomegatherium) tarijense, appears to be a junior synonym of M. americanum, and merely a small individual.[11]

The species Megatherium filholi Moreno, 1888 of the Pampas, previously thought to be a junior synonym of M. americanum representing juvenile individuals, was suggested to be a distinct valid species in 2019.[12]

Megatherium gallardoi Ameghino & Kraglievich 1921 from the Ensenadan of Argentina was suggested to be a valid species in 2008, most closely related to M. americanum and M. altiplanicum.[13]

M. parodii Hoffstetter 1949, and M. istilarti Kraglievich 1925 have not had their validity assessed in recent literature.

Evolution

Bru's 1796 skeletal drawing of M. americanum

Ground sloths are a diverse group belonging to superorder Xenarthra, which also includes extinct pampatheres and glyptodonts, as well as living tree sloths, anteaters and armadillos. One of the four major eutherian radiations, this superorder evolved in isolation in South America while it was an island continent during the Paleogene and Neogene. The family to which Megatherium belongs, Megatheriidae, is related within superfamily Megatherioidea to the extinct families Nothrotheriidae and Megalonychidae, and to living three-toed sloths of family Bradypodidae, as deduced recently from collagen[14] and mitochondrial DNA[15] sequences obtained from subfossil bones.[citation needed]

During the Pliocene, the Central American Isthmus formed, causing the Great American Interchange, and a mass extinction of much of the indigenous South American megafauna. Xenarthrans were largely unaffected and continued to thrive in spite of competition from the northern immigrants. Ground sloths were prominent among the various South American animal groups to migrate northwards into North America, where they remained and flourished until the late Pleistocene.[16]

The rhinoceros-sized Promegatherium of the Miocene is suggested to be the ancestor of Megatherium. The oldest (and smallest) species of Megatherium is M. altiplanicum of Pliocene Bolivia.[1] It was very similar to Promegatherium, and was also about the size of a rhinoceros. M. tarijense has been regarded as a medium-sized Megatherium species, larger than M. altiplanicum, but smaller than M. americanum. It roamed from the Tarija Basin in Bolivia to Yantac in Peru.[11] The oldest-known remains of Megatherium from the Pampas dates to the late Pliocene, around 3.58 million years ago.[17] Species of Megatherium became larger over time, with the largest species, M. americanum of the Late Pleistocene, reaching the size of an African elephant. The oldest records of M. americanum are from the latter half of the Middle Pleistocene, around 0.4 Ma (400 ka) ago.[18]

The following sloth family phylogenetic tree is based on collagen and mitochondrial DNA sequence data (see Fig. 4 of Presslee et al., 2019).[14]

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Description

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Megatherium americanum was one of the largest animals in its habitat, weighing up to Lua error: Internal error: The interpreter exited with status 1.,[19][20][21][22] with a shoulder height of Lua error: Internal error: The interpreter exited with status 1. and length of Lua error: Internal error: The interpreter exited with status 1. from head to tail.[23][24][25] It was one of the largest ground sloths, about as big as modern Asian elephants. Megatherium species were members of the abundant Pleistocene megafauna, large mammals that lived during the Pleistocene epoch.Lua error: Internal error: The interpreter exited with status 1.

Megatherium had a robust skeleton with a large pelvic girdle and a broad muscular tail. Its large size enabled it to feed at heights unreachable by other contemporary herbivores. Rising on its powerful hind legs and using its tail to form a tripod, Megatherium could support its massive body weight while using the curved claws on its long forelegs to pull down branches with the choicest leaves. This sloth, like a modern anteater, walked on the sides of its feet because its claws prevented it from putting them flat on the ground. Although it was primarily a quadruped, its trackways show that it was capable of bipedal locomotion. Biomechanical analysis also suggests it had adaptations to bipedalism.[21]

One study has proposed that Megatherium was mostly hairless, like modern elephants, because its large size and small surface-area-to-volume ratio would have made it susceptible to overheating.[26]

Mouth

Megatherium had a narrow, cone-shaped mouth and prehensile lips that were probably used to select particular plants and fruits.[27] Megatherium also possessed the narrowest muzzle of all ground sloths from the Pleistocene, possibly meaning it was a very selective eater, able to carefully pick and choose which leaves and twigs to consume.[27] While some evidence suggests the animal could use its tongue to differentiate and select its foliage, the lips probably had a more important role in this.[28] In Megatherium, the stylohyal and epihyal bones (parts of the hyoid bone which supports the tongue and is located in the throat) were fused together, and the apparatus lies farther upwards the throat, which, together with the elongated, steeply inclined mandibular symphysis, indicates a relatively shorter geniohyoid muscle and thus more limited capacity for tongue protrusion.[29] Analysis of wear and the biomechanics of the chewing muscles suggests that they chewed vertically. Megatheres displayed deeper jaws than other sloths.[19]

Like other sloths, Megatherium lacked the enamel, deciduous dentition and dental cusp patterns of other mammals. Instead of enamel, the tooth displays a layer of cementum, orthodentine and modified orthodentine, creating a soft, easily abraded surface.[28] The teeth of M. americanum exhibit extreme hypsodonty, indicative of its gritty, fibrous diet. Their teeth in side view show interlocking V-shaped biting surfaces, although they are nearly square in cross-section and exhibit bilophodonty. The teeth are spaced equidistantly in a series, located in the back of the mouth, which leaves space at the predentary, but with no diastema, although the length of this tooth row and of the predentary spout can vary by species.Lua error: Internal error: The interpreter exited with status 1.[19]

Habitat

M. americanum restoration

Megatherium inhabited woodland and grassland environments of the lightly wooded areas of South America, with a Late Pleistocene range centred around the Pampas[30] where it was an endemic species, as recently as 10,000 years ago. Megatherium was adapted to temperate, arid or semiarid open habitats. An example of these most recent finds is at Cueva del Milodón in Patagonian Chile .[31] The closely related genus Eremotherium (that has been classified occasionally as part of Megatherium)[32] lived in more tropical environments further north, and invaded temperate North America as part of the Great American Interchange.

Paleobiology

Restoration of M. americanum by Robert Bruce Horsfall, 1913

The giant ground sloth lived mostly in groups, but it may have lived singly in caves. It probably had mainly a browsing diet in open habitats, but also it probably fed on other moderate to soft tough food. For millions of years, the sloth did not have many enemies to bother it, so it was probably a diurnal animal.Lua error: Internal error: The interpreter exited with status 1.

The giant ground sloth was a herbivore, feeding on leaves such as yuccas, agaves and grasses.Lua error: Internal error: The interpreter exited with status 1. While it fed chiefly on terrestrial plants, it could also stand on its hind legs, using its tail as a balancing tripod, and reach for upper growth vegetation. It would pull itself upright to sit on its haunches or to stand and then tugged at plants with its feet, digging them up with the five sharp claws on each foot. The sloth used its simple teeth to grind down food before swallowing it, and its highly developed cheek muscles helped in this process. The sloth's stomach was able to digest coarse and fibrous food.Lua error: Internal error: The interpreter exited with status 1. It is likely that it spent a lot of time resting to aid digestion.

M. americanum skull
Claw of Megatherium

A recent morpho-functional analysis[19] indicates that M. americanum was adapted for strong vertical biting. The teeth are hypsodont and bilophodont, and the sagittal section of each loph is triangular with a sharp edge. This suggests that the teeth were used for cutting, rather than grinding, and that hard fibrous food was not the primary dietary component.

While it has been suggested that the giant sloth may have been partly carnivorous, this is a controversial claim. Richard Fariña and Ernesto Blanco of the Universidad de la República in Montevideo have analysed a fossil skeleton of M. americanum and discovered that its olecranon—the part of the elbow to which the triceps muscle attaches—was very short. This adaptation is found in carnivores and optimises speed rather than strength. The researchers say this would have enabled M. americanum to use its claws like daggers. They suggest that to add nutrients to its diet, Megatherium may have taken over the kills of Smilodon. Based on the estimated strength and mechanical advantage of its biceps, it has been proposed that Megatherium could have overturned adult glyptodonts (large, armored xenarthrans, related to armadillos) as a means of scavenging or hunting these animals.[33] However, noting that sloths lack the carnassials typical of predators and that traces of bone are absent from the many preserved deposits of sloth dung, Paul Martin has described this proposal as "fanciful".[upper-alpha 1] Carbon isotope analysis has found that Megatherium has isotope values similar to other megafaunal herbivores such as mammoths, glyptodonts and Macrauchenia, and significantly unlike omnivorous and carnivorous mammals, suggesting that Megatherium was an obligate herbivore.[34]

Extinction

M. americanum sculpture in Crystal Palace Park

The youngest unambiguous dates for Megatherium are from the end of the Late Pleistocene. Supposed early Holocene dates obtained for Megatherium and other Pampas megafauna have been questioned, with suggestions that they are likely due to humic acid contamination of the collagen used to radiocarbon date the bones.[4] Megatherium disappeared simultaneously along with the vast majoriy (>80%) of other large (megafaunal) South American mammals, as part of the Quaternary extinction event.[35] The use of bioclimatic envelope modeling indicates that the area of suitable habitat for Megatherium had shrunk and become fragmented by the mid-Holocene. While this alone would not likely have caused its extinction, it has been cited as a possible contributing factor.[36]

Towards the end of the Late Pleistocene, humans first arrived in the Americas, with some of the earliest evidence of humans in South America being the Monte Verde II site in Chile, dating to around 14,500 years Before Present ~(12,500 BC).[37] The extinction interval of Megatherium and other megafauna coincides with the appearance and abundance of Fishtail projectile points, which are suggested to have been used to hunt megafauna, across the Pampas region and South America more broadly.[38] There is evidence for the butchery of Megatherium by humans. Two M. americanum bones, an ulna[39] and an atlas vertebra,[40] from separate collections, bear cut marks suggestive of butchery, with the latter suggested to represent an attempt to exploit the contents of the head.[40] A kill site dating to around 12,600 years Before Present (BP), is known from Campo Laborde in the Pampas in Argentina, where a single individual of M. americanum was slaughtered and butchered, which is the only confirmed giant ground-sloth kill site in the Americas. At the site several stone tools were present, including the fragment of a projectile point.[4] Another possible kill site is Arroyo Seco 2 near Tres Arroyos in the Pampas in Argentina, where M. americanum bones amongst those of other megafauna were found associated with humans artifacts dating to approximately 14,782–11,142 cal yr BP.[41] This hunting may have been a factor in its extinction.[38]

Cultural references

The Megatherium Club, named for the extinct animal and founded by William Stimpson, was a group of Washington, D.C.-based scientists who were attracted to that city by the Smithsonian Institution's rapidly growing collection, from 1857 to 1866.

Notes

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References

  1. ↑ 1.0 1.1 1.2 Saint-André, P. A.; De Iuliis, G. (2001). "The smallest and most ancient representative of the genus Megatherium Cuvier, 1796 (Xenarthra, Tardigrada, Megatheriidae), from the Pliocene of the Bolivian Altiplano". Geodiversitas 23 (4): 625–645. http://www.mnhn.fr/publication/geodiv/g01n4a4.pdf. Retrieved 14 April 2016. 
  2. ↑ 2.0 2.1 Zurita, A. E.; Carlini, A. A.; Scillato-Yané, G. J.; Tonni, E. P. (2004). "Mamíferos extintos del Cuaternario de la Provincia del Chaco (Argentina) y su relación con aquéllos del este de la región pampeana y de Chile". Revista Geológica de Chile 31 (1): 65–87. doi:10.4067/S0716-02082004000100004. 
  3. ↑ 3.0 3.1 3.2 Argot, Christine (21 May 2008). "Changing Views in Paleontology: The Story of a Giant (Megatherium, Xenarthra)". in Sargis, E. J.; Dagosto, M.. Mammalian Evolutionary Morphology: A Tribute to Frederick S. Szalay. Springer. pp. 37–50. ISBN 978-1-4020-6997-0. OCLC 236490247. https://books.google.com/books?id=6_n2Sr7kIO8C&pg=PA37. 
  4. ↑ 4.0 4.1 4.2 Politis, Gustavo G.; Messineo, Pablo G.; Stafford, Thomas W.; Lindsey, Emily L. (March 2019). "Campo Laborde: A Late Pleistocene giant ground sloth kill and butchering site in the Pampas" (in en). Science Advances 5 (3): eaau4546. doi:10.1126/sciadv.aau4546. ISSN 2375-2548. PMID 30854426. Bibcode: 2019SciA....5.4546P. 
  5. ↑ 5.0 5.1 5.2 Pujos, François (2006). "Megatherium celendinense sp. nov. from the Pleistocene of the Peruvian Andes and the phylogenetic relationships of Megatheriines". Palaeontology 49 (2): 285–306. doi:10.1111/j.1475-4983.2006.00522.x. Bibcode: 2006Palgy..49..285P. 
  6. ↑ De Iuliis, Gerardo; Pujos, François; Tito, Giuseppe (2009-12-12). "Systematic and taxonomic revision of the Pleistocene ground sloth Megatherium (Pseudomegatherium) tarijense (Xenarthra: Megatheriidae)". Journal of Vertebrate Paleontology 29 (4): 1244–1251. doi:10.1671/039.029.0426. ISSN 0272-4634. Bibcode: 2009JVPal..29.1244D. https://doi.org/10.1671/039.029.0426. 
  7. ↑ Piñero, J. M. L. (Spring 1988). "Juan Bautista Bru (1740–1799) and the description of the genus Megatherium". Journal of the History of Biology 21 (1): 147–163. doi:10.1007/BF00125797. 
  8. ↑ Bürgl, Hans (1956). "Restos de Megatherium y otros fósiles de Quipile, Cundinamarca". INGEOMINAS: 1–14. http://catalogo.sgc.gov.co/cgi-bin/koha/opac-detail.pl?biblionumber=10457. Retrieved 2017-05-03. 
  9. ↑ De Porta, Jaime (1961). "La posición estratigráfica de la fauna de Mamíferos del pleistoceno de la Sabana de Bogotá". Boletín de Geología, Universidad Industrial de Santander 7: 37–54. http://revistas.uis.edu.co/index.php/revistaboletindegeologia/article/viewFile/4260/4556. Retrieved 2017-05-03. 
  10. ↑ Pujos, François; Salas, Rodolfo (2004). "A new species of Megatherium (Mammalia: Xenarthra: Megatheriidae) from the Pleistocene of Sacaco and Tres Ventanas, Peru". Palaeontology 47 (3): 579–604. doi:10.1111/j.0031-0239.2004.00376.x. Bibcode: 2004Palgy..47..579P. 
  11. ↑ 11.0 11.1 De Iuliis, G.; Pujos, F.; Tito, G. (2009). "Systematic and taxonomic revision of the Pleistocene ground sloth Megatherium (Pseudomegatherium) tarijense (Xenarthra: Megatheriidae)". Journal of Vertebrate Paleontology 29 (4): 1244–1251. doi:10.1671/039.029.0426. Bibcode: 2009JVPal..29.1244D. 
  12. ↑ Agnolin, Federico L.; Chimento, Nicolás R.; Brandoni, Diego; Boh, Daniel; Campo, Denise H.; Magnussen, Mariano; De Cianni, Francisco (2018-09-01). "New Pleistocene remains of Megatherium filholi Moreno, 1888 (Mammalia, Xenarthra) from the Pampean Region: Implications for the diversity of Megatheriinae of the Quaternary of South America" (in en). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 289 (3): 339–348. doi:10.1127/njgpa/2018/0777. ISSN 0077-7749. 
  13. ↑ Brandoni, Diego; Soibelzon, Esteban; Scarano, Alejo Carlos (December 2008). "On Megatherium gallardoi (Mammalia, Xenarthra, Megatheriidae) and the Megatheriinae from the Ensenadan (lower to middle Pleistocene) of the Pampean region, Argentina". Geodiversitas. ISSN 1280-9659. http://ri.conicet.gov.ar/handle/11336/80911. 
  14. ↑ 14.0 14.1 Presslee, S.; Slater, G. J.; Pujos, F.; Forasiepi, A. M.; Fischer, R.; Molloy, K.; Mackie, M.; Olsen, J. V. et al. (2019). "Palaeoproteomics resolves sloth relationships". Nature Ecology & Evolution 3 (7): 1121–1130. doi:10.1038/s41559-019-0909-z. PMID 31171860. Bibcode: 2019NatEE...3.1121P. http://eprints.whiterose.ac.uk/147061/1/5426_3_merged_1554730549.pdf. 
  15. ↑ Delsuc, F.; Kuch, M.; Gibb, G. C.; Karpinski, E.; Hackenberger, D.; Szpak, P.; Martínez, J. G.; Mead, J. I. et al. (2019). "Ancient Mitogenomes Reveal the Evolutionary History and Biogeography of Sloths". Current Biology 29 (12): 2031–2042.e6. doi:10.1016/j.cub.2019.05.043. PMID 31178321. https://www.researchgate.net/publication/333647272. 
  16. ↑ Martin, P. S. (2005). Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America (Illustrated ed.). University of California Press. ISBN 978-0520231412. OCLC 58055404. https://books.google.com/books?id=gfpla1OY268C. Retrieved 2014-09-11. 
  17. ↑ Chimento, Nicolás R.; Agnolin, Federico L.; Brandoni, Diego; Boh, Daniel; Magnussen, Mariano; De Cianni, Francisco; Isla, Federico (April 2021). "A new record of Megatherium (Folivora, Megatheriidae) in the late Pliocene of the Pampean region (Argentina)" (in en). Journal of South American Earth Sciences 107: 102950. doi:10.1016/j.jsames.2020.102950. Bibcode: 2021JSAES.10702950C. 
  18. ↑ Chichkoyan, K.V.; Martínez-Navarro, B.; Moigne, A.-M.; Cioppi, E.; Belinchón, M.; Lanata, J.L. (March 2017). "Description and interpretation of a Megatherium americanum atlas with evidence of human intervention". Rivista Italiana di Paleontologia e Stratigrafia 123 (1): 51-64. doi:10.13130/2039-4942/8019. ISSN 0035-6883. https://www.researchgate.net/publication/316562027. 
  19. ↑ 19.0 19.1 19.2 19.3 Bargo, M. S. (2001). "The ground sloth Megatherium americanum: Skull shape, bite forces, and diet". Acta Palaeontologica Polonica 46 (2): 173–192. http://www.app.pan.pl/archive/published/app46/app46-173.pdf. Retrieved 2012-07-22. 
  20. ↑ Blanco, R.E; Czerwonogora, Ada (2003). "The gait of Megatherium Cuvier 1796 (Mammalia, Xenarthra, Megatheriidae)". Senckenbergiana Biologica 83 (1): 61–68. 
  21. ↑ 21.0 21.1 Casinos, A. (1996). "Bipedalism and quadrupedalism in Megatherium: An attempt at biomechanical reconstruction". Lethaia 29 (1): 87–96. doi:10.1111/j.1502-3931.1996.tb01842.x. Bibcode: 1996Letha..29...87C. 
  22. ↑ "Splendid oddness: revisiting the curious trophic relationships of South American Pleistocene mammals and their abundance". Anais da Academia Brasileira de Ciências 86 (1): 311–31. March 2014. doi:10.1590/0001-3765201420120010. PMID 24676170. 
  23. ↑ Turner, Alan (2004). Prehistoric Mammals. National Geographic. pp. 78–79. ISBN 9780792269977. 
  24. ↑ BBC (2012). "Megatherium Wildfacts". BBC. http://www.bbc.co.uk/nature/wildfacts/factfiles/456.shtml. 
  25. ↑ Haines, T.; Chambers, P. (2007). The Complete Guide to Prehistoric Life. Italy: Firefly Books Ltd.. pp. 192–193. ISBN 978-1-55407-181-4. 
  26. ↑ Fariña, R. (June 2002). "Megatherium, the hairless: appearance of the great Quaternary sloths (Mammalia;Xenarthra)". Ameghiniana 39 (2): 241–244. https://www.researchgate.net/publication/297846446. 
  27. ↑ 27.0 27.1 Bargo, M. S.; Toledo, N.; Vizcaíno, S. F. (2006). "Muzzle of South American Pleistocene ground sloths (Xenarthra, Tardigrada)". Journal of Morphology 267 (2): 248–263 (see p. 260). doi:10.1002/jmor.10399. PMID 16315216. 
  28. ↑ 28.0 28.1 Ferigolo, J. (1985). "Evolutionary trends of the histological pattern in the teeth of Edentata (Xenarthra)". Archives of Oral Biology 30 (1): 71–82. doi:10.1016/0003-9969(85)90027-5. ISSN 0003-9969. PMID 3857888. 
  29. ↑ Perez, L. M.; Toledo, N.; De Lullis, G.; Bargo, M. S.; Vizcaino, S. F. (2010). "Morphology and Function of the Hyoid Apparatus of Xenarthran Fossils (Mammalia)". Journal of Morphology 271 (9): 1119–1133. doi:10.1002/jmor.10859. PMID 20730924. 
  30. ↑ McKenna, M. C.; Bell, S. K. (1997). Classification of Mammals Above the Species Level'. New York: Columbia University Press. pp. 631. ISBN 978-0231110129. 
  31. ↑ C. Michael Hogan (2008) Cueva del Milodon, Megalithic Portal
  32. ↑ Cisneros, J. C. (2005). "New Pleistocene vertebrate fauna from El Salvador". Revista Brasileira de Paleontologia 8 (3): 239–255. doi:10.4072/rbp.2005.3.09. https://www.researchgate.net/publication/228650581. Retrieved 2014-05-27. 
  33. ↑ Fariña, R. A.; Blanco, R. E. (1996). "Megatherium, the stabber". Proceedings of the Royal Society of London 263 (1377): 1725–1729. doi:10.1098/rspb.1996.0252. PMID 9025315. 
  34. ↑ Bocherens, H.; Cotte, M.; Bonini, R.A.; Straccia, P.; Scian, D.; Soibelzon, L.; Prevosti, F.J. (August 2017). "Isotopic insight on paleodiet of extinct Pleistocene megafaunal Xenarthrans from Argentina". Gondwana Research 48: 7–14. doi:10.1016/j.gr.2017.04.003. Bibcode: 2017GondR..48....7B. 
  35. ↑ Anthony D. Barnosky; Paul L. Koch; Robert S. Feranec; Scott L. Wing; Alan B. Shabel (2004). "Assessing the Causes of Late Pleistocene Extinctions on the Continents". Science 306 (5693): 70–75. doi:10.1126/science.1101476. PMID 15459379. Bibcode: 2004Sci...306...70B. 
  36. ↑ Lima-Ribeiro, Matheus Souza (December 2012). "Potential Suitable Areas of Giant Ground Sloths Dropped Before its Extinction in South America: the Evidences from Bioclimatic Envelope Modeling.". Natureza & Conservação 10 (2): 145–151. doi:10.4322/natcon.2012.022. 
  37. ↑ Dillehay, Tom D.; Pino, Mario; Ocampo, Carlos (2021-01-02). "Comments on Archaeological Remains at the Monte Verde Site Complex, Chile" (in en). PaleoAmerica 7 (1): 8–13. doi:10.1080/20555563.2020.1762399. ISSN 2055-5563. https://www.tandfonline.com/doi/full/10.1080/20555563.2020.1762399. 
  38. ↑ 38.0 38.1 Prates, Luciano; Perez, S. Ivan (2021-04-12). "Late Pleistocene South American megafaunal extinctions associated with rise of Fishtail points and human population" (in en). Nature Communications 12 (1): 2175. doi:10.1038/s41467-021-22506-4. ISSN 2041-1723. PMID 33846353. Bibcode: 2021NatCo..12.2175P. 
  39. ↑ Chichkoyan, Karina V.; Martínez-Navarro, Bienvenido; Moigne, Anne-Marie; Belinchón, Margarita; Lanata, José L. (June 2017). "The exploitation of megafauna during the earliest peopling of the Americas: An examination of nineteenth-century fossil collections" (in en). Comptes Rendus Palevol 16 (4): 440–451. doi:10.1016/j.crpv.2016.11.003. Bibcode: 2017CRPal..16..440C. 
  40. ↑ 40.0 40.1 Autoecologia Humana del Quaternari Departament d'Història i Història de l'Art Universitat Rovira i Virgili Martínez-Navarro, B.; Chichkoyan, K.V.; Moigne, A.-M.; Cioppi, E.; Belinchón, M.; Lanata, J.L. (2017). Description and interpretation of a Megatherium americanum atlas with evidence of human intervention. Rivista Italiana di Paleontologia e Stratigrafia. OCLC 1084743779. https://www.researchgate.net/publication/316562027. 
  41. ↑ Bampi, Hugo; Barberi, Maira; Lima-Ribeiro, Matheus S. (December 2022). "Megafauna kill sites in South America: A critical review" (in en). Quaternary Science Reviews 298: 107851. doi:10.1016/j.quascirev.2022.107851. Bibcode: 2022QSRv..29807851B. https://linkinghub.elsevier.com/retrieve/pii/S0277379122004826. 

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External links

Wikidata ☰ Q310387 entry


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