Wikipedia

Megatherium

For the often misspelt bacterium, seeBacillus megaterium.

Megatherium(/mɛɡəˈθɪəriəm/meg-ə-THEER-ee-əm;from Greekméga(μέγα) 'great' +theríon(θηρίον) 'beast') is an extinctgenusofground slothsendemic toSouth Americathat lived from the EarlyPliocene[1]through the end of theLate Pleistocene.[2]It is best known for theelephant-sizedtype speciesMegatherium americanum,primarily known from thePampas,but ranging southwards to northernmostPatagoniaand northwards to southernBoliviaduring the lateMiddle Pleistoceneand Late Pleistocene. Various other species belonging to the subgenusPseud Omega theriumranging in size comparable to considerably smaller thanM. americanumare known from the Andean region.

Megatherium
Temporal range: EarlyPliocene[1]to EarlyHolocene,5–0.010Ma
↓
Possible later date of 0.008 Ma
M. americanumskeleton,Natural History Museum, London
Scientific classificationEdit this classification
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
  • †M. altiplanicumSaint-Andre & De Iuliis, 2001
  • †M. americanumCuvier, 1796
  • †M. gallardoiAmeghino & Kraglievich, 1921
Pseud Omega therium
  • †M. celendinensePujos, 2006
  • †M. medinaePhilippi, 1893
  • †M. sundtiPhilippi, 1893
  • †M. tarijenseGervais&Ameghino,1880
  • †M. urbianiPujos & Salas, 2004
Map showing the distribution of allMegatheriumspecies in red, inferred from fossil finds
Synonyms
  • EssonodontheriumAmeghino 1884
  • OrocanthusAmeghino 1885
  • NeoracanthusAmeghino 1889

The first (holotype) specimen ofMegatheriumwas discovered in 1787 on the bank of theLuján Riverin what is now northern Argentina. The specimen was then shipped toSpainthe following year wherein it caught the attention of the French paleontologistGeorges Cuvier,who named the animal in 1796 and was the first to determine, by means ofcomparative anatomy,thatMegatheriumwas a giant sloth.

Megatheriumis part of the sloth familyMegatheriidae,which also includes the closely related and similarly giantEremotherium,comparable in size toM. americanum,which was native to tropical South America, Central America and North America as far north as the southern United States.

Megatherium americanumis thought to have been abrowserthat fed on the foliage and twigs of trees and shrubs using ablack rhinoceros–like prehensile upper lip. Despite its large body size,Megatherium americanumis widely thought to have been able to adopt a bipedal posture at least while standing, which allowed it to feed on high-growing leaves, as well as possibly to use its claws for defense.

Megatheriumbecame extinct around 12,000 years ago as part of theend-Pleistocene extinction event,simultaneously with the majority of other large mammals in the Americas. The extinctions followed thefirst arrival of humans in the Americas,and one and potentially multiplekill siteswhereM. americanumwas slaughtered and butchered is known, suggesting that hunting could have been a factor in its extinction.[3]

Research history

Illustration of the first specimen ofMegatherium americanumfrom 1796
Life illustration ofMegatherium americanumfrom 1863, depicting it with a short trunk

The earliest specimen ofMegatherium americanumwas discovered in 1787 by Manuel de Torres, aDominicanfriar and naturalist, from a ravine on the banks of theLujan Riverin what is now northern Argentina, which at the time was part of theViceroyalty of the Río de la Platain theSpanish Empire.Torres described the bones as a ‘wonder and providence of the Lord’. On the orders of the then viceroy of la Plata,Nicolás Cristóbal del Campo, Marqués de Loreto,the specimen was moved to the capitalBuenos Aires.There the skeleton was drawn for the first time byJosé Custodio Sáa y Fariain a horse-like posture. Campo summoned a number of local indigenous leaders to ask if they had heard of the animal. The skeleton was then transferred by Campo to the Royal Cabinet of Natural History of Madrid (now theNational Museum of Natural SciencesMNCN) in 7 crates, which had arrived and been unpacked by late 1788.[4]

At the direction of the cabinets main taxidermist Juan Bautista Bru, the specimen was then mounted for public exhibition (which remains unaltered in the modern museum display). In 1796 a scientific description of the skeleton was published authored by Bru along with engineer Joseph Garriga, with engravings by Manuel Navarro. As the work was going through the process of publication in 1795, preliminary prints of the paper were obtained by French diplomat Philippe-Rose Roume who was in Madrid at the time, who sent them to theNational Museum of Natural History(Muséum national d'histoire naturelle) in Paris, France, where they were seen by French anatomist and paleontologistGeorges Cuvier.[4]

Cuvier, working solely from the prints from Madrid and not visiting the specimen personally,[4]and usingcomparative anatomywith "edentate" mammals (now recognised as members of the orderXenarthra) in the collection of the Paris museum,[5]correctly recognised that the remains represented those of a giant sloth, and an animal that was entirely extinct and not living. In early 1796, somewhat before the full publication of the work by Bru, Garriga and Navarro, Cuvier published a paper naming the speciesMegatherium americanum(literally "Great American beast" ),[4]becoming the first fossil mammal to be identified with both agenusand species name. Which description hadpriorityhas been controversial in the past. Cuvier later wrote a fuller description in 1804, which was republished in his famous 1812 bookRecherches sur les ossemens fossiles de quadrupèdes.Cuvier identifiedMegatheriumas a sloth primarily on the basis of its skull morphology, thedental formulaand the shoulder, while regarding the anatomy of its limbs as more similar toarmadillosandanteaters.Cuvier suggested that based on the proportions of its limbs (which are approximately equal to each other), thatMegatheriumdid not jump or run, nor crawl like living sloths, with the presence of aclavicleand well developed crests on thehumerus,suggesting to Cuvier that the animal probably used its forelimbs to grasp.[5]A later publication in 1823 by Cuvier suggested that giant carapaces found in the Pampas also belonged toMegatherium,but British paleontologistRichard Owenin 1839 demonstrated that these actually belonged to another extinct group of xenarthrans calledglyptodontsthat were related to armadillos.[6]

Additional remains ofMegatheriumwere collected byCharles Darwinduring theVoyage of the Beaglein the 1830s, these remains were assigned by Richard Owen in 1840 to the speciesMegatherium cuvieri,which had been named byAnselme Gaëtan Desmarestin 1822. These remains are now assigned toM. americanum.[6]

19th centuryM. americanumsculpture inCrystal Palace Park,London, England

Owen later wrote a monograph series from 1851 to 1860 thoroughly describing the anatomy ofM. americanum.[7][8][9][10][11][12]

From the late 19th century onward additional species ofMegatheriumwere described. In 1888 Argentine explorerFrancisco Morenoerected the speciesMegatherium filholifor remains found in the Late Pleistocene of Argentina.[13][14][15]In 1880Paul GervaisandFlorentino Ameghinodescribed the speciesM. tarijensefrom remains of Pleistocene age found in Bolivia. In 1893Rodolfo Amando Philippierected the speciesM. sundtiandM. medinaefrom remains found in the Pleistocene of Bolivia and Chile, respectively.[16][17]In 1921, Florentino's brotherCarlos Ameghinoand Lucas Kraglievich described the speciesMegatherium gallardoibased on remains found in the Pampas of Northern Argentina, of Early-Middle Pleistocene age.[18][19]In 2001, the speciesM. altiplanicumwas described based on remains found in the Pliocene of Bolivia.[20]In 2004, the speciesMegatherium urbinaiwas erected based on remains found in Pleistocene aged deposits in Peru.[21]In 2006, the speciesMegatherium celendinensewas erected for remains of Pleistocene age found in the Peruvian Andes.[22]

Taxonomy and evolution

Megatheriumis divided into 2subgenera,MegatheriumandPseud Omega therium.Taxonomy according to Pujos (2006) and De Iuliiset al(2009):[22][23]

  • SubgenusMegatherium
    • †M. altiplanicumSaint-André & de Iuliis 2001
    • †M. americanumCuvier 1796
    • †M. gallardoiAmeghino & Kraglievich, 1921
  • SubgenusPseud Omega theriumKraglievich 1931
    • †M. celendinensePujos 2006
    • †M. medinaePhilippi 1893
    • †M. sundtiPhilippi 1893
    • †M. tarijenseGervais & Ameghino, 1880
    • †M. urbinaiPujos & Salas 2004

Megatherium gallardoiAmeghino & Kraglievich, 1921from the Pampas dating to theEarlytoMiddle Pleistocene[15]has sometimes been regarded as a synonym ofM. americanum.[19]The speciesMegatherium filholiMoreno, 1888also from the Pleistocene of the Pampas region, historically regarded to be a junior synonym ofM. americanumrepresenting juvenile individuals has been suggested to be valid by some recent authors.[14]Megatherium gaudryiMoreno (1888)from Argentina, of uncertain temporal provenance but possibly Pliocene in age, may also be valid.[15]

Mitochondrial DNAsequences obtained fromM. americanumindicates thatthree-toed sloths(Bradypus) are their closest living relatives. Phylogeny of sloths after Delsuc et al. 2019.[24]

Folivora(sloths)

†Caribbean sloths

Mylodontoidea
Megatherioidea

Megatheriidaeis suggested to have diverged from other sloth families during theOligocene,around 30 million years ago.[24]The subfamily to whichMegatheriumbelongs,Megatheriinae,first appeared in theMiddle MioceneinPatagonia,at least 12 million years ago, represented by the genusMegathericulus.[25]The earliest known remains of the genusMegatheriumare known from thePliocene,found in Bolivia (M. altiplanicum) and the Pampas (indeterminate species), dating to at least 3.6 million years ago.[15][20]M. altiplanicumis suggested to be more closely related toM. americanumthan to species ofPseud Omega therium.Phylogeny of Megatheriinae after Pujos, 2006:[22]

Megatheriinae

Plesi Omega therium

Megathericulus

Megatheriops

Pyramiodontheriumbergi

Pyramiodontherium brevirostrum

Eremotherium

Megatherium
Megatherium(Megatherium)

Megatherium americanum

Megatherium altiplanicum

Megatherium(Pseud Omega therium)

Megatherium sundti

Megatherium urbinai

Megatherium celendinense

Megatherium medinae

Megatherium tarijense

Megatherium americanumfirst appears in the fossil record during the second half of theMiddle Pleistocene,from around 400,000 years ago.[26]

Description

Size

Size ofMegatherium americanumcompared to a human

M. americanumis one of the largest known ground sloths, with a total body length of around 6 metres (20 ft).[27]Volumetricanalysis suggests that a full grownM. americanumweighed around 3,700–4,000 kilograms (8,200–8,800 lb), comparable to an Asian elephant.[28][29][30]The Late Pleistocene Andean-AltiplanoPseud Omega theriumspeciesMegatherium celendinensewas likely comparable in size. These species were only rivalled in size amongst ground sloths by the closely relatedEremotheriumand the distantly relatedLestodon.The ChileanPseud Omega theriumspeciesM. sundtiwas much smaller, with an estimated body mass of only 1,253 kilograms (2,762 lb), with the PeruvianMegatherium urbinai,BolivianMegatherium tarijenseand the ChileanMegatherium medinae(all also belonging toPseud Omega therium) also having a considerably smaller body size thanM. americanum.[31]The PlioceneMegatherium(Megatherium) speciesM. altiplanicumhas been estimated to weigh 977–1,465 kilograms (2,154–3,230 lb).[20]

Skull and jaws

Skull and lower jaws ofM. americanum(note: nasal septum is broken) Scale bar = 10 cm, ~ 4 inches

The head ofMegatheriumis relatively small compared to body size.[29]The skull is roughly cylindrical in shape, with the cranial region of the skull being narrow. Thejugalbone ofM. americanumhas strongly developed ascending and descendingprocesses.[32]The skull ofM. americanumhas a relatively smallcranial cavity(and thus brain) relative to skull size, with the skull having extensivesinusspaces.[33]In many species ofMegatherium,the lower jaw is relatively deep, which served to accommodate the very long hypselodont (evergrowing) teeth,[20]which are considerably proportionally longer than those of other ground sloths. Like other ground sloths, the number of teeth in the jaw is reduced to 5 and 4 teeth in each half of the upper and lower jaws, respectively, and the teeth lack enamel. The teeth ofMegatherium americanumhave sharp crests separated by v-shaped valleys, which interlock with the teeth on the opposing jaw.[32]These teeth were self-sharpening, akin to rodent incisors.[34]The skull ofM. americanumhas a relatively narrow snout/muzzle with aossifiednasal septum,and is suggested to have had a thickprehensileupper lip, similar to that of the livingblack rhinoceros,which compensated for the lack of teeth at the front of the jaws.[35]The morphology of thehyoid bonesinMegatheriumsuggests that they were relatively rigid, this along with the short distance between the hyoid and themandibular symphysis(the joint connecting the two halves of the lower jaw) suggests that the tongue had limited ability to protrude, and thusMegatheriumdid not have a long prehensile tongue, contrary to what was often historically suggested.[36]The skull and jaws ofM. americanumshow adaptation to powerful vertical biting.[32]M. americanumandM. altiplanicumare distinguished from species of the subgenusPseud Omega theriumby the fusion of themaxillaandpremaxilla,while members ofPseud Omega theriumare distinguished from those species by their flatoccipital condyles.[22]

Axial skeleton

Like other xenarthrans, the posterior trunk vertebrae ofMegatherium americanumhave additional xenarthrous processes that articulate with the other vertebrae. Theischiumwas connected to thecaudal vertebrae,forming asynsacrum.Thesacrumwas composed of 5 vertebrae. Thepubic symphysisis reduced. The tail is large in size.[29]

Limbs

Foot ofMegatheriumshowing enlarged and elongate calcaneum (left) and lateral digits

The bones of the forelimbs ofM. americanumare relatively elongate and thin. The three fingers in the middle of the hand bore claws, while the cuneiform hand bones did not touch theulna.[29]Theolecranonprocess of the ulna was relatively short.[37]Like other xenarthrans, but unlike most other mammals,Megatheriumpossessesclavicles(collarbones), which serves to support the forelimb. Like other sloths, the clavicle is merged with theacromionof thescapula.[38]The femur was massive and roughly rectangular in shape.[29]As in most megatheriines, thetibiaandfibulaofMegatheriumspecies are fused together at their proximal (closest to hip) end, while inM. americanumandM. tarijense,they are also fused together at their distal (closest to foot) ends.[39]The foot was heavily modified from those of other mammals and earlier ground sloths, with a reduction in the number of digits on the inner part of the foot (digits I and II being lost), the increase in the size and robustness (thickness) of themetapodialelements of the outer digits, with the loss or reduction of thephalangealbones. Thecalcaneumis wide and elongate posteriorly. The foot is suggested to have been inwardly rotated, historically the foot was suggested to be near vertical, though a recent study suggests that the angle was much shallower. The weight was primarily borne on the outer digits and the calcaneum.[40]M. urbinaidiffers fromM. americanumbased on various characters of the feet and hands.[21]

Ecology

UprightMegatherium americanumin an open landscape alongside two individuals of theglyptodontGlyptodon.

Remains ofMegatherium americanumhave been found in low elevation areas to the east of the Andes mountains in northernPatagonia,thePampasand adjacent areas in what is now northern Argentina, Uruguay, Paraguay, southern Bolivia andRio Grande do Sulin southern Brazil.[31]Megatherium americanuminhabitedtemperate,arid-tosemi aridopen habitats.[41]During theLast Glacial Period,the Pampas was generally drier than it is at present with many areas exhibiting asteppe-like environment dominated by grass, with some areas of woodland.[31]

Although some authors have suggested thatMegatheriumwas an omnivore,[37]isotopic analysis has supported an entirely herbivorous diet forMegatherium.[42]Megatherium americanumis suggested to have been abrowserthat was a selective feeder on the foliage, twigs and fruits of trees and shrubs.[35][43]The sharp cusps of the teeth served to shear plant material.[34]Megatheriumis widely thought to have been able to adopt a bipedal posture to use its forelimbs to grasp vegetation, though whether it was capable of moving in this posture is uncertain.[44]Analysis of injuries on the clavicles ofM. americanumindividuals suggests that the species probably habitually moved in a quadrupedal posture and assumed a bipedal posture next to trees to feed on high-growing leaves, likely using its forelimbs to brace itself against the tree trunk, as well as to pull down higher branches within reach of its prehensile lip.[38]Isotopic analysis suggests that some individuals ofM. americanumat certain times and places also consumed grass.[45]The smallerMegatherium tarijensehas been suggested to have had a mixed feeding-browsing diet.[46]Preservedcoprolitesattributed toMegatheriumsuggests that its diet included plants likeFabiana,Ephedra(Ephedra breana),beebrush,Junellia,andChuquiraga.[47]

Whether or notMegatheriumhad a slowmetabolismlike living tree sloths is uncertain. Analysis of thenutrient foraminain thediaphysis(shaft) of the femur ofMegatherium americanumshows that they are more similar to those of other large living mammals like elephants than living tree sloths, which may suggest that it had a metabolism more similar to non-xenarthran mammals and was capable of vigorous activity similar to living elephants.[48]However, isotopic analysis of teeth suggests thatMegatheriumhad a somewhat lowerbody temperaturethan non-xenarthran mammals, around 30–32 °C (86–90 °F), comparable to that of living tree sloths, implying a lower metabolic rate.[49]Megatherium americanumhas been traditionally reconstructed as being covered with a thick coat of fur.[49]Due to its very large body size, some authors have alternatively argued thatMegatherium americanumwas probably hairless like modern elephants for thermodynamic reasons.[50]However this has been disputed, with other authors suggesting based on thermodynamic modelling assuming a living xenarthran-like metabolism thatMegatheriumspecies probably had a dense coat of fur around 3 centimetres (1.2 in) thick to be able to tolerate the relatively cool environments they inhabited.[49]

Based on fossil trackways and the anatomy of its inner ear, which is considerably different from living sloths and more similar to those of armadillos, species ofMegatherium,while probably not capable of moving at considerable speed due to limitations of their skeletal anatomy (with one study estimating a max speed of approximately 2.2 metres per second (7.2 ft/s) or 7.92 kilometres per hour (4.92 mph), a fraction of the 5–6 metres per second (16–20 ft/s) or 18–21.6 kilometres per hour (11.2–13.4 mph) top speed observed for living elephants[49]) were likely significantly more agile and mobile than living sloths, which are only capable of moving 0.5–0.6 kilometres per hour (0.31–0.37 mph). Species ofMegatheriumlikely relied on their large adult body size to protect themselves against predators.[51]Like many other large mammals,Megatheriumis suggested to have had a slow life cycle in accordance with aK-selectionstrategy.Megatherium americanumis suggested to have given birth to a single large offspring at a time.[52]

The anatomy of its forelimb bones suggests thatM. americanumhad the ability to rapidly and powerfully extend its arms, which likely made its claws effective stabbing weapons.[37]It may have used its claws like this to defend itself, as living tree sloths do.[38]Although some authors in the 19th century suggested thatMegatheriumengaged in digging behaviour, this has been disputed by other scholars, and the morphology of its limb bones do not appear to display significant adaptations to digging unlike some ground sloths such asmylodontids.[53]

In the Pampas,Megatherium americanumlived alongside other megafauna species, including the large ground slothLestodon,along with the smaller (but still large) ground slothsMylodon,Glossotherium,andScelidotherium,theglyptodonts(very large armadillos with fused round carapaces covering the body)Glyptodon,Doedicurus,andPanochthus,the large camel-like ungulateMacraucheniaand rhinoceros-likeToxodon,thegomphothere(elephant-relative)Notiomastodon,the equinesHippidionandEquus neogeus,the large short-faced bearArctotherium,and the large sabertooth catSmilodon.[54]The range ofMegatherium americanumoverlaps little with its similarly sized tropical relativeEremotherium,with their co-occurrence only confidently reported from a few localities in Southern Brazil, and it is unclear whether they were contemporary at these localities.[55]

Relationship with humans and extinction

During theLate Pleistocene,six species ofMegatheriumwere present in South America, includingM. americanumin the Pampas and adjacent regions, and the 5 species ofPseud Omega theriumin the vicinity of the Andes.[31]

The youngest unambiguous dates forMegatheriumare from the end of the Late Pleistocene. Supposed early Holocene dates obtained forMegatherium americanumand other Pampas megafauna have been questioned, with suggestions that they are likely due tohumic acidcontamination of thecollagenused toradiocarbon datethe bones.[3]Megatheriumdisappeared simultaneously along with the vast majority (>80%) of other large (megafaunal) South American mammals, as part of theend-Pleistocene extinction event.[56]The use of bioclimatic envelope modeling indicates that the area of suitable habitat forMegatheriumhad 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.[57]

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 theMonte Verde IIsite in Chile, dating to around 14,500 yearsBefore Present(~12,500 BC).[58]The extinction interval ofMegatheriumand other megafauna coincides with the appearance and abundance ofFishtail points,which are suggested to have been used to hunt megafauna, across the Pampas region and South America more broadly.[59]At the Paso Otero 5 site in the Pampas of northeast Argentina, Fishtail points are associated with burned bones ofMegatherium americanumand other extinct megafauna. The bones appear to have been deliberately burned as a source of fuel. Due to the poor preservation of the bones there is no clear evidence of human modification.[60]

There is evidence for the butchery ofMegatheriumby humans. TwoM. americanumbones, anulna[61]and anatlas vertebra,[62]from separate collections, bear cut marks suggestive of butchery, with the latter suggested to represent an attempt to exploit the contents of the head.[62]Akill sitedating to around 12,600 years Before Present (BP), is known from Campo Laborde in the Pampas in Argentina, where a single individual ofM. americanumwas slaughtered and butchered at the edge of a swamp, 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.[3]Another possible kill site is Arroyo Seco 2 nearTres Arroyosin the Pampas in Argentina, whereM. americanumbones amongst those of other megafauna were found associated with human artifacts dating to approximately 14,782–11,142 cal yr BP.[63]This hunting may have been a factor in its extinction.[59]

Cultural references

TheMegatherium Club,named for the extinct animal and founded byWilliam Stimpson,was a group ofWashington, D.C.–based scientists who were attracted to that city by theSmithsonian Institution's rapidly growing collection, from 1857 to 1866.

References

  1. ^abSaint-André, P. A.; De Iuliis, G. (2001)."The smallest and most ancient representative of the genusMegatheriumCuvier, 1796 (Xenarthra, Tardigrada, Megatheriidae), from the Pliocene of the Bolivian Altiplano "(PDF).Geodiversitas.23(4):625–645. Archived fromthe original(PDF)on 2013-10-29.Retrieved14 April2016.
  2. ^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. ^abcPolitis, 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".Science Advances.5(3): eaau4546.Bibcode:2019SciA....5.4546P.doi:10.1126/sciadv.aau4546.ISSN2375-2548.PMC6402857.PMID30854426.
  4. ^abcdPimentel, Juan (2021), Pimentel, Juan; Thurner, Mark (eds.),"Megatherium",New World Objects of Knowledge,A Cabinet of Curiosities, University of London Press, pp.231–236,ISBN978-1-908857-82-8,JSTORj.ctv1vbd275.38,retrieved2024-04-23
  5. ^abArgot, Christine (2008), Sargis, Eric J.; Dagosto, Marian (eds.),"Changing Views in Paleontology: The Story of a Giant (Megatherium, Xenarthra)",Mammalian Evolutionary Morphology,Vertebrate Paleobiology and Paleoanthropology Series, Dordrecht: Springer Netherlands, pp.37–50,doi:10.1007/978-1-4020-6997-0_3,ISBN978-1-4020-6996-3,retrieved2024-04-23
  6. ^abFernicola, J. C., Vizcaino, S. F., & De Iuliis, G. (2009). The fossil mammals collected by Charles Darwin in South America during his travels on board the HMS Beagle.Revista De La Asociación Geológica Argentina,64(1), 147–159. Retrieved from https://revista.geologica.org.ar/raga/article/view/1339
  7. ^Owen R (1851) On theMegatherium(Megatherium americanum,Blumenbach). Part I. Preliminary observations on the exogenous processes of vertebrae. Phil Trans R Soc Lond 141:719–764
  8. ^Owen R (1855) On theMegatherium(Megatherium americanum,Cuvier and Blumenbach). Part II. Vertebrae of the trunk. Phil Trans R Soc Lond 145:359–388
  9. ^Owen R (1856) On theMegatherium(Megatherium americanum,Cuvier and Blumenbach). Part III. The skull. Phil Trans R Soc Lond 146:571–589
  10. ^Owen R (1858) On theMegatherium(Megatherium americanum,Cuvier and Blumenbach). Part IV. Bones of the anterior extremities. Phil Trans R Soc Lond 148:261–278
  11. ^Owen R (1859) On theMegatherium(Megatherium americanum,Cuvier and Blumenbach). Part V. Bones of the posterior extremities. Phil Trans R Soc Lon149:809–829
  12. ^Owen R (1861) Memoir on theMegatherium,or Giant Ground-sloth of America (Megatherium americanum,Cuvier). Williams and Norgate, London
  13. ^Moreno, F.P. (1888): Informe preliminar de los progresos del Museo La Plata durante el primer semestre de 1888. – Boletín del Museo La Plata, 1: 1-35.
  14. ^abAgnolin, 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".Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen.289(3):339–348.doi:10.1127/njgpa/2018/0777.hdl:11336/80117.ISSN0077-7749.S2CID134660849.
  15. ^abcdChimento, 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)".Journal of South American Earth Sciences.107:102950.Bibcode:2021JSAES.10702950C.doi:10.1016/j.jsames.2020.102950.
  16. ^Philippi, R.A. 1893a. Vorläufige Nachricht über fossile Säugethierknochen von Ulloma, Bolivia. Zeitschrift der deutschen geologischen Gesellschaft 45: 87–96.
  17. ^Philippi, R.A. 1893b. Noticias preliminares sobre huesos fósiles de Ulloma. Anales de la Universidad de Chile 82: 499–506.
  18. ^C. Ameghino, L. Kraglievich Descripción del "Megatherium gallardoi"C. Amegh. descubierto en el Pampeano inferior de la ciudad de Buenos Aires Anales del Museo Nacional de Historia Natural de Buenos Aires, 31 (1921), pp. 134–156
  19. ^abBrandoni D., Soibelzon E. & Scarano A. 2008. —OnMegatherium gallardoi(Mammalia, Xenarthra, Megatheriidae) and the Megatheriinae from the Ensenadan (lower to middle Pleistocene) of the Pampean region, Argentina.Geodiversitas2008 (4): 793-804.
  20. ^abcdSaint-André P.-A. & de Iuliis G. 2001. —The smallest and most ancient representative of the genusMegatheriumCuvier, 1796 (Xenarthra, Tardigrada, Megatheriidae), from the Pliocene of the Bolivian Altiplano.Geodiversitas2001 (4): 625–645.
  21. ^abPujos, François; Salas, Rodolfo (May 2004)."A new species of Megatherium (Mammalia: Xenarthra: Megatheriidae) from the Pleistocene of Sacaco and Tres Ventanas, Peru".Palaeontology.47(3):579–604.Bibcode:2004Palgy..47..579P.doi:10.1111/j.0031-0239.2004.00376.x.ISSN0031-0239.
  22. ^abcdPujos, François (2006)."Megatherium celendinense sp. nov.from the Pleistocene of the Peruvian Andes and the phylogenetic relationships of Megatheriines ".Palaeontology.49(2):285–306.Bibcode:2006Palgy..49..285P.doi:10.1111/j.1475-4983.2006.00522.x.S2CID84225654.
  23. ^De Iuliis, Gerardo; Pujos, François; Tito, Giuseppe (2009-12-12). "Systematic and taxonomic revision of the Pleistocene ground sloth Megatherium (Pseud Omega therium) tarijense (Xenarthra: Megatheriidae)".Journal of Vertebrate Paleontology.29(4):1244–1251.Bibcode:2009JVPal..29.1244D.doi:10.1671/039.029.0426.ISSN0272-4634.S2CID84272333.
  24. ^abDelsuc, Frédéric; Kuch, Melanie; Gibb, Gillian C.; Karpinski, Emil; Hackenberger, Dirk; Szpak, Paul; Martínez, Jorge G.; Mead, Jim I.; McDonald, H. Gregory; MacPhee, Ross D.E.; Billet, Guillaume; Hautier, Lionel; Poinar, Hendrik N. (June 2019)."Ancient Mitogenomes Reveal the Evolutionary History and Biogeography of Sloths".Current Biology.29(12): 2031–2042.e6.Bibcode:2019CBio...29E2031D.doi:10.1016/j.cub.2019.05.043.PMID31178321.
  25. ^Brandoni, Diego; Carlini, Alfredo A; Anaya, Federico; Gans, Phil; Croft, Darin A (September 2018)."New Remains of Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) from the Serravallian (Middle Miocene) of Bolivia; Chronological and Biogeographical Implications".Journal of Mammalian Evolution.25(3):327–337.doi:10.1007/s10914-017-9384-y.ISSN1064-7554.
  26. ^Prado, José Luis; Alberdi, María Teresa; Bellinzoni, Jonathan (June 2021)."Pleistocene Mammals from Pampean Region (Argentina). Biostratigraphic, Biogeographic, and Environmental Implications".Quaternary.4(2): 15.doi:10.3390/quat4020015.ISSN2571-550X.
  27. ^Naish, Darren (November 2005)."Fossils explained 51: Sloths".Geology Today.21(6):232–238.doi:10.1111/j.1365-2451.2005.00538.x.ISSN0266-6979.
  28. ^Brassey, Charlotte A.; Gardiner, James D. (August 2015)."An advanced shape-fitting algorithm applied to quadrupedal mammals: improving volumetric mass estimates".Royal Society Open Science.2(8): 150302.Bibcode:2015RSOS....250302B.doi:10.1098/rsos.150302.ISSN2054-5703.PMC4555864.PMID26361559.
  29. ^abcdeCasinos, Adrià (March 1996)."Bipedalism and quadrupedalism in Megatheriurn: an attempt at biomechanical reconstruction".Lethaia.29(1):87–96.Bibcode:1996Letha..29...87C.doi:10.1111/j.1502-3931.1996.tb01842.x.ISSN0024-1164.
  30. ^Fariña RA, Czerwonogora A, di Giacomo M (March 2014)."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.doi:10.1590/0001-3765201420120010.PMID24676170.
  31. ^abcdMcDonald, H. Gregory (June 2023)."A Tale of Two Continents (and a Few Islands): Ecology and Distribution of Late Pleistocene Sloths".Land.12(6): 1192.doi:10.3390/land12061192.ISSN2073-445X.
  32. ^abcBargo, M.S. 2001.The ground slothMegatherium americanum:Skull shape, bite forces, and diet.–Acta Palaeontologica Polonica46,2, 173–192.
  33. ^Boscaini, Alberto; Iurino, Dawid A.; Sardella, Raffaele; Gaudin, Timothy J.; Pujos, François (2023), Dozo, María Teresa; Paulina-Carabajal, Ariana; Macrini, Thomas E.; Walsh, Stig (eds.),"The Endocranial Cavities of Sloths (Xenarthra, Folivora): Insights from the Brain Endocast, Bony Labyrinth, and Cranial Sinuses",Paleoneurology of Amniotes,Cham: Springer International Publishing, pp.737–760,doi:10.1007/978-3-031-13983-3_19,ISBN978-3-031-13982-6,retrieved2024-05-14
  34. ^abGreen, Jeremy L.; Kalthoff, Daniela C. (2015-08-03)."Xenarthran dental microstructure and dental microwear analyses, with new data for Megatherium americanum (Megatheriidae)".Journal of Mammalogy.96(4):645–657.doi:10.1093/jmammal/gyv045.ISSN0022-2372.
  35. ^abBargo, M. Susana; Toledo, Néstor; Vizcaíno, Sergio F. (February 2006)."Muzzle of South American Pleistocene ground sloths (Xenarthra, Tardigrada)".Journal of Morphology.267(2):248–263.doi:10.1002/jmor.10399.ISSN0362-2525.PMID16315216.
  36. ^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.PMID20730924.S2CID8106788.
  37. ^abcFariña, R. A.; Blanco, R. E. (1996-12-22)."Megatherium, the stabber".Proceedings of the Royal Society of London. Series B: Biological Sciences.263(1377):1725–1729.doi:10.1098/rspb.1996.0252.ISSN0962-8452.PMID9025315.
  38. ^abcChichkoyan, Karina V.; Villa, Chiara; Winkler, Viola; Manuelli, Luigi; Acuña Suarez, Gabriel E. (2022-12-16)."Paleopathologies of the Clavicles of the Giant Ground Sloth Megatherium americanum (Mammalia, Xenarthra) from the Pleistocene of the Pampean Region (Argentina)".Ameghiniana.59(6).doi:10.5710/AMGH.15.10.2022.3509.ISSN0002-7014.
  39. ^Bonini, Ricardo A.; Brandoni, Diego (December 2015)."Pyramiodontherium Rovereto (Xenarthra, Tardigrada, Megatheriinae) from the Early Pliocene of San Fernando, Catamarca Province, Argentina".Ameghiniana.52(6):647–655.doi:10.5710/AMGH.16.06.2015.2902.hdl:11336/42299.ISSN0002-7014.
  40. ^Toledo, Néstor; De Iuliis, Gerardo; Vizcaíno, Sergio F.; Bargo, M. Susana (December 2018)."The Concept of a Pedolateral Pes Revisited: The Giant Sloths Megatherium and Eremotherium (Xenarthra, Folivora, Megatheriinae) as a Case Study".Journal of Mammalian Evolution.25(4):525–537.doi:10.1007/s10914-017-9410-0.ISSN1064-7554.
  41. ^Varela, Luciano; Tambusso, P. Sebastián; Patiño, Santiago J.; Di Giacomo, Mariana; Fariña, Richard A. (December 2018)."Potential Distribution of Fossil Xenarthrans in South America during the Late Pleistocene: co-Occurrence and Provincialism".Journal of Mammalian Evolution.25(4):539–550.doi:10.1007/s10914-017-9406-9.ISSN1064-7554.
  42. ^Bocherens, Hervé; Cotte, Martin; Bonini, Ricardo A.; Straccia, Pablo; Scian, Daniel; Soibelzon, Leopoldo; Prevosti, Francisco J. (August 2017)."Isotopic insight on paleodiet of extinct Pleistocene megafaunal Xenarthrans from Argentina".Gondwana Research.48:7–14.Bibcode:2017GondR..48....7B.doi:10.1016/j.gr.2017.04.003.hdl:11336/56592.
  43. ^Bargo, M. S., & Vizcaíno, S. F. (2008). Paleobiology of Pleistocene Ground Sloths (Xenarthra, Tardigrada): Biomechanics, Morphogeometry and Ecomorphology Applied to the Masticatory Apparatus.Ameghiniana,45(1), 175–196.
  44. ^Milne, Nick; Toledo, Nestor; Vizcaíno, Sergio F. (September 2012)."Allometric and Group Differences in the Xenarthran Femur".Journal of Mammalian Evolution.19(3):199–208.doi:10.1007/s10914-011-9171-0.hdl:11336/193251.ISSN1064-7554.
  45. ^Sanz-Pérez, Dánae; Hernández Fernández, Manuel; Tomassini, Rodrigo L.; Montalvo, Claudia I.; Beilinson, Elisa; Gasparini, Germán M.; Domingo, Laura (June 2022)."The Pampean region (Argentina) underwent larger variation in aridity than in temperature during the late Pleistocene: New evidence from the isotopic analysis of mammalian taxa".Quaternary Science Reviews.286:107555.Bibcode:2022QSRv..28607555S.doi:10.1016/j.quascirev.2022.107555.
  46. ^Dantas, Mário A. T.; Campbell, Sean Cody; McDonald, H. Gregory (December 2023)."Paleoecological inferences about the Late Quaternary giant sloths".Journal of Mammalian Evolution.30(4):891–905.doi:10.1007/s10914-023-09681-5.ISSN1064-7554.
  47. ^H. Gregory McDonald and Gerardo de Iuliis:Fossil history of sloths.In: Sergio F. Vizcaíno and WJ Loughry (eds.): The Biology of the Xenarthra. University Press of Florida, 2008, pp. 51–52.
  48. ^Varela, Luciano; Tambusso, Sebastián; Fariña, Richard (2024-08-07)."Femora nutrient foramina and aerobic capacity in giant extinct xenarthrans".PeerJ.12:e17815.doi:10.7717/peerj.17815.ISSN2167-8359.PMC11316464.PMID39131616.
  49. ^abcdDeak, Michael D.; Porter, Warren P.; Mathewson, Paul D.; Lovelace, David M.; Flores, Randon J.; Tripati, Aradhna K.; Eagle, Robert A.; Schwartz, Darin M.; Butcher, Michael T. (March 2025)."Metabolic skinflint or spendthrift? Insights into ground sloth integument and thermophysiology revealed by biophysical modeling and clumped isotope paleothermometry".Journal of Mammalian Evolution.32(1).doi:10.1007/s10914-024-09743-2.ISSN1064-7554.
  50. ^Fariña, R. A. (2002).Megatherium,the hairless: appearance of the great Quaternary sloths (Mammalia; Xenarthra). Ameghiniana, 39(2), 241–244.
  51. ^Billet, G.; Germain, D.; Ruf, I.; de Muizon, C.; Hautier, L. (December 2013)."The inner ear of Megatherium and the evolution of the vestibular system in sloths".Journal of Anatomy.223(6):557–567.doi:10.1111/joa.12114.ISSN0021-8782.PMC3842198.PMID24111879.
  52. ^Andrea, Elissamburu (July 2016)."Prediction of offspring in extant and extinct mammals to add light on paleoecology and evolution".Palaeogeography, Palaeoclimatology, Palaeoecology.453:73–79.doi:10.1016/j.palaeo.2016.03.033.
  53. ^Amson, Eli; Nyakatura, John A. (December 2018)."The Postcranial Musculoskeletal System of Xenarthrans: Insights from over Two Centuries of Research and Future Directions".Journal of Mammalian Evolution.25(4):459–484.doi:10.1007/s10914-017-9408-7.ISSN1064-7554.
  54. ^S.F. Vizcaíno, R.A. Fariña, J.C. FernicolaYoung Darwin and the ecology and extinction of Pleistocene South American fossil mammalsRev. Asoc. Geol. Argent., 64 (1) (2009), pp. 160-169
  55. ^Lopes, Renato Pereira; Dillenburg, Sergio Rebello; Pereira, Jamil Corrêa; Sial, Alcides Nóbrega (2021-09-26)."The paleoecology of Pleistocene giant megatheriid sloths: stable isotopes (δ13C, δ18O) of co-occurring Megatherium and Eremotherium from southern Brazil".Revista Brasileira de Paleontologia.24(3):245–264.doi:10.4072/rbp.2021.3.06.
  56. ^Barnosky, Anthony D.; Koch, Paul L.; Feranec, Robert S.; Wing, Scott L.; Shabel, Alan B. (2004). "Assessing the Causes of Late Pleistocene Extinctions on the Continents".Science.306(5693):70–75.Bibcode:2004Sci...306...70B.CiteSeerX10.1.1.574.332.doi:10.1126/science.1101476.PMID15459379.S2CID36156087.
  57. ^Lima-Ribeiro, Matheus Souza; et al. (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.
  58. ^Dillehay, Tom D.; Pino, Mario; Ocampo, Carlos (2021-01-02)."Comments on Archaeological Remains at the Monte Verde Site Complex, Chile".PaleoAmerica.7(1):8–13.doi:10.1080/20555563.2020.1762399.ISSN2055-5563.S2CID224935851.
  59. ^abPrates, Luciano; Perez, S. Ivan (2021-04-12)."Late Pleistocene South American megafaunal extinctions associated with rise of Fishtail points and human population".Nature Communications.12(1): 2175.Bibcode:2021NatCo..12.2175P.doi:10.1038/s41467-021-22506-4.ISSN2041-1723.PMC8041891.PMID33846353.
  60. ^G. Martínez, M. A. Gutiérrez,Paso Otero 5: A summary of the interdisciplinary lines of evidence for reconstructing early human occupation and paleoenvironment in the Pampean region, Argentina,inPeuplements et Préhistoire de l’Amérique,D. Vialou, Ed. (Muséum National d’ Histoire Naturelle. Departement de Prehistoire, U.M.R, Paris, 2011), pp. 271–284.
  61. ^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".Comptes Rendus Palevol.16(4):440–451.Bibcode:2017CRPal..16..440C.doi:10.1016/j.crpv.2016.11.003.
  62. ^abMartínez-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.OCLC1084743779.
  63. ^Bampi, Hugo; Barberi, Maira; Lima-Ribeiro, Matheus S. (December 2022)."Megafauna kill sites in South America: A critical review".Quaternary Science Reviews.298:107851.Bibcode:2022QSRv..29807851B.doi:10.1016/j.quascirev.2022.107851.S2CID253876769.
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