PBDB Taxon

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Megalonychidae

Mammalia - Megalonychidae

Taxonomy

Megalonychidae was named by Gervais (1855).

It was synonymized subjectively with Megatheriidae by Hay (1902).

It was assigned to Gravigrada by Ameghino (1891), Ameghino (1894), Ameghino (1897); to Edentata by Kurten and Anderson (1980); to Pilosa by Thurmond and Jones (1981); to Megalonychoidea by Carroll (1988); to Xenarthra by Nowak (1991), Muizon and McDonald (1995); to Eutardigrada by Gaudin (1995); to Phyllophaga by McDonald and Muizon (2002); to Pilosa by McDonald and Naples (2007); to Pilosa by McDonald et al. (2013), McDonald and Carranza-Castañeda (2017); and to Megatherioidea by White and MacPhee (2001), Pujos et al. (2007), Varela et al. (2019).

Subtaxa

Amphihapalops, Amphiocnus, Analcimorphus, Choloepodinae, Deseadognathus, Diheterocnus, Eleutherodon, Eucholoeops, Eugeronops, Geronops, Hapalops (syn. Stenocephalus), Holomegalonyx, Hyperleptus (syn. Tapinotherium), Mecorhinus, Megalocninae, Megalonychinae, Megalonychops, Megalonychotherium, Meizonyx, Mesocnus, Mesopotamocnus, Metopotherinae, Metopotherini, Microcnus, Miocnus, Nohochichak, Nothropus, Ocnopodinae, Ortotheriinae, Ortotherium, Paranabradys, Paraplanops, Pattersonocnus, Pliomorphus, Protomegalonyx, Pseudhapalops, Pseudortotherium, Torcellia, Trematherium, Urumacocnus, Xibalbaonyx, Zacatzontli

Synonyms

Choloepina was named by Gray (1871). It is extant.

It was synonymized subjectively with Megalonychidae by Adam (1999).

Synonymy list

Year	Name and author
1855	Megalonychidae Gervais
1891	Megalonychidae Ameghino p. 32
1894	Megalonychidae Ameghino p. 147
1897	Megalonychidae Ameghino p. 505
1980	Megalonychidae Kurten and Anderson p. 135
1981	Megalonychidae Thurmond and Jones p. 177
1988	Megalonychidae Carroll
1991	Megalonychidae Nowak
1995	Megalonychidae Gaudin
1995	Megalonychidae Muizon and McDonald p. 224
2001	Megalonychidae White and MacPhee
2002	Megalonychidae McDonald and Muizon p. 350
2007	Megalonychidae McDonald and Naples p. 154
2007	Megalonychidae Pujos et al.
2013	Megalonychidae McDonald et al. p. 1228
2017	Megalonychidae McDonald and Carranza-Castañeda
2019	Megalonychidae Varela et al.

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
subclass	Synapsida
—	Therapsida	()

Rank	Name	Author
infraorder	Cynodontia	()
—	Mammaliamorpha
—	Mammaliaformes
class	Mammalia
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
—	Americatheria
—	Xenarthra	()
infraorder	Pilosa	Flower 1883
—	Folivora
class	Eufolivora	Delsuc et al. 2001
superfamily	Megatherioidea	Gray 1821
family	Megalonychidae	Gervais 1855
family	Megalonychidae	Gervais 1855

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Fm. †Megalonychidae Gervais 1855

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G. †Amphihapalops Ameghino 1891

†Amphihapalops cadens Ameghino 1891

†Amphihapalops congermanus Ameghino 1891

†Amphihapalops gallaicus Ameghino 1891

G. †Amphiocnus Kraglievich 1922

†Amphiocnus paranense Kraglievich 1922

G. †Analcimorphus Ameghino 1891

†Analcimorphus giganteus Ameghino 1894

†Analcimorphus inversus Ameghino 1891

Subfm. †Choloepodinae MacPhee 2001

G. †Acratocnus Anthony 1916

†Acratocnus antillensis Matthew 1931

†Acratocnus odontrigonus Anthony 1916

†Acratocnus ye MacPhee et al. 2001

G. Choloepus Illiger 1811

Choloepus agustinus Allen 1913

Choloepus andinus Allen 1913

Choloepus capitalis Allen 1913

Choloepus didactylus Linnaeus 1758 [Linnaeus's two toed sloth]

Invalid names: Choloepus braziliensis Fitzinger 1871 [synonym], Choloepus curi Link 1795 [synonym], Choloepus didactylus columbianus Gray 1871 [synonym], Choloepus florenciae Allen 1913 [synonym], Choloepus guianensis Fitzinger 1871 [synonym], Choloepus napensis Lönnberg 1922 [synonym], Choloepus unau Link 1795 [synonym]

Choloepus hoffmanni Peters 1858 [Hoffmann's two-toed sloth]

G. †Neocnus Arredondo 1961

†Neocnus comes Miller 1929

†Neocnus dousman MacPhee et al. 2001

†Neocnus gliriformis Matthew 1931

†Neocnus major Arredondo 1961

†Neocnus toupiti MacPhee et al. 2001

G. †Paulocnus Hooijer 1962

†Paulocnus petrifactus Hooijer 1962

Invalid names: Acratocnini Varona 1974 [empty], Choloepodini Gray 1871 [empty], Cubanocnini Varona 1974 [empty]

G. †Deseadognathus Carlini and Scillato-Yané 2004

†Deseadognathus riggsi Carlini and Scillato-Yané 2004

G. †Diheterocnus Kraglievich 1928

G. †Eleutherodon Mercerat 1891

†Eleutherodon heteroclitus Mercerat 1891

G. †Eucholoeops Amegino 1887

†Eucholaeops titan Lydekker 1894

†Eucholoeops ingens Ameghino 1887

Invalid names: Eucholoeops curtus Ameghino 1894 [synonym], Eucholoeops externus Ameghino 1891 [synonym], Eucholoeops fronto Ameghino 1891 [synonym], Eucholoeops lafonei Mercerat 1891 [synonym], Eucholoeops latirostris Ameghino 1891 [synonym]

†Eucholoeops latifrons Mercerat 1891

†Eucholoeops litoralis Ameghino 1891

†Eucholoeops titans Lyddekker 1894

G. †Eugeronops Ameghino 1891

G. †Geronops Ameghino 1891

†Geronops circularis Ameghino 1891

G. †Hapalops Ameghino 1887

†Hapalops adteger Amegino 1887

†Hapalops aguirrei Mercerat 1891

†Hapalops angustipalatus Ameghino 1891

†Hapalops antistis Ameghino 1897

†Hapalops atlanticus Ameghino 1891

†Hapalops australis Mercerat 1891

†Hapalops boulei Mercerat 1891

†Hapalops brachycephalus Ameghino 1894

†Hapalops brevipalatus Ameghino 1891

Invalid names: Stenocephalus hybridus Mercerat 1891 [synonym]

†Hapalops cilindricus Ameghino 1891

†Hapalops cognathus Mercerat 1891

†Hapalops congermanus Ameghino 1891

†Hapalops crassidens Ameghino 1891

†Hapalops crassignathus Ameghino 1891

†Hapalops crassissimus Ameghino 1894

†Hapalops curvus Ameghino 1899

†Hapalops depressipalatus Ameghino 1891

†Hapalops diverssidens Ameghino 1891

†Hapalops elongatus Ameghino 1891

†Hapalops forticulus Ameghino 1891

†Hapalops gracilidens Ameghino 1891

†Hapalops grandaevus Moreno and Mercerat 1891

†Hapalops grandis Ameghino 1894

†Hapalops hyperleptus Ameghino 1891

†Hapalops indifferens Ameghino 1887

Invalid names: Stenocephalus australis Mercerat 1891 [synonym]

†Hapalops infernalis Ameghino 1887

†Hapalops latus Ameghino 1894

†Hapalops longiceps Scott 1903

†Hapalops longipalatus Ameghino 1891

†Hapalops minutus Ameghino 1891

†Hapalops platycephalus Scott 1903

†Hapalops ponderosus Scott 1903

†Hapalops primus Ameghino 1894

†Hapalops rectagulidens Ameghino 1891

†Hapalops robustus Ameghino 1891

†Hapalops rostratus Ameghino 1887

Invalid names: Xyophorus simus Ameghino 1887 [synonym]

†Hapalops rutimeyeri Ameghino 1891

†Hapalops sectus Ameghino 1891

†Hapalops subcuadratus Ameghino 1891

†Hapalops testudinatus Ameghino 1891

†Hapalops vulpiceps Scott 1903

Invalid names: Stenocephalus Mercerat 1891 [synonym]

G. †Holomegalonyx Scillato-Yané 1979

G. †Hyperleptus Ameghino 1891

†Hyperleptus garzonianus Ameghino 1891

†Hyperleptus schissognathus Ameghino 1891

†Hyperleptus sectus Ameghino 1891

Invalid names: Tapinotherium aguirrei Mercerat 1891 [synonym]

Invalid names: Tapinotherium Mercerat 1891 [synonym]

G. †Mecorhinus Ameghino 1894

†Mecorhinus primus Ameghino 1894

Subfm. †Megalocninae

G. †Imagocnus MacPhee and Iturralde-Vinent 1994

†Imagocnus zazae MacPhee and Iturralde-Vincent 1994

G. †Megalocnus Leidy 1868

†Megalocnus rodens Matthew and Paula Couto 1959

†Megalocnus zile MacPhee et al. 2000

G. †Parocnus Miller 1929

†Parocnus browni Matthew 1931

†Parocnus serus Miller 1929

Invalid names: Megalocnini Kraglievich 1923 [empty], Mesocnini Varona 1974 [empty]

Subfm. †Megalonychinae Trouessart 1904

G. †Ahytherium Cartelle et al. 2008

†Ahytherium aureum Cartelle et al. 2008

Invalid names: Iporangabradyx Dos Santos 1991 [nomen nudum], Iporangabradyx collecti Dos Santos 1991 [nomen nudum]

G. †Australonyx De Iuliis et al. 2009

†Australonyx aquae De Iuliis et al. 2009

G. †Ereptodon Leidy 1853

†Ereptodon priscus Leidy 1853

G. †Megalonyx Harlan 1825

†Megalonyx curvidens Matthew 1924

†Megalonyx cuvieri Lund 1839

†Megalonyx dissimilis Leidy 1855

†Megalonyx gigas Marsh 1874

†Megalonyx jeffersonii Desmarest 1822 [Jefferson's ground sloth]

Invalid names: Megalonyx brachycephalus Sellards 1941 [synonym], Megalonyx californicus Stock 1913 [synonym], Megalonyx hogani Stovall 1940 [synonym], Megalonyx laqueatus Harlan 1831 [synonym], Megalonyx milleri Lyon 1938 [synonym]

†Megalonyx leidyi Lindahl 1892

†Megalonyx leptostomus Cope 1893

Invalid names: Megalonyx rohrmani Gustafson 1978 [synonym]

†Megalonyx loxodon Cope 1871

†Megalonyx mathisi Hirschfeld and Webb 1968

†Megalonyx obtusidens Webb and Perrigo 1985

†Megalonyx scalper Cope 1899

†Megalonyx sierrensis Sinclair 1905 [sloth]

†Megalonyx tortulus Cope 1871

†Megalonyx validus Leidy 1868

†Megalonyx wheatleyi Cope 1871

Invalid names: Megalonyx sphenodon Cope 1871 [synonym]

Invalid names: Megalonyx gracilis Lund 1893 [nomen nudum]

G. †Megistonyx McDonald et al. 2013

†Megistonyx oreobios McDonald et al. 2013

G. †Pliometanastes Hirschfeld and Webb 1968

†Pliometanastes protistus Hirschfeld and Webb 1968

Invalid names: Pliometanastes galushai Hirschfeld and Webb 1968 [synonym]

G. †Sinclairia Ameghino 1912

†Sinclairia oregoniana Ameghino 1912

G. †Megalonychops Kraglievich 1927

†Megalonychops primigenius Kraglievich 1926

G. †Megalonychotherium Scott 1904

†Megalonychotherium atavus Scott 1903

G. †Meizonyx Webb and Perrigo 1985

†Meizonyx salvadorensis Webb and Perrigo 1985

G. †Mesocnus Matthew 1931

†Mesocnus torrei Matthew 1931

G. †Mesopotamocnus Brandoni 2014

†Mesopotamocnus brevirostrum Bordas 1941

Subfm. †Metopotherinae Ameghino 1902

G. †Hapaloides Ameghino 1902

†Hapaloides ignavus Ameghino 1902

†Hapaloides laeviusculus Ameghino 1902

†Hapaloides ponderosus Ameghino 1902

G. †Proschismotherium Ameghino 1902

†Proschismotherium oppositum Ameghino 1902

Subfm. †Metopotherini Ameghino 1894

G. †Adiastemus Ameghino 1894

†Adiastemus compressidens Ameghino 1894

G. †Metopotherium Ameghino 1891

†Metopotherium splendens Ameghino 1891

G. †Uranokyrtus Ameghino 1894

†Uranokyrtus bombifrons Ameghino 1894

G. †Microcnus Matthew 1931

G. †Miocnus Matthew 1931

G. †Nohochichak McDonald et al. 2017

†Nohochichak xibalbahkah McDonald et al. 2017

G. †Nothropus Burmeister 1882

†Nothropus carcaranensis Bordas 1942

†Nothropus nordenskioldi Pujos et al. 2007

†Nothropus priscus Burmeister 1882

Subfm. †Ocnopodinae Hoffstetter 1954

G. †Ocnopus Reinhardt 1875

†Ocnopus gracilis Lund 1840

Subfm. †Ortotheriinae Ameghino 1889

G. †Menilaus Ameghino 1891

G. †Ortotherium Ameghino 1885

†Ortotherium berroi Kraglievich 1932

†Ortotherium laticurvatum Ameghino 1885

Invalid names: Amphiocnus seneum Ameghino 1891 [synonym], Amphiocnus seneus Ameghino 1891 [synonym], Menilaus affinis Ameghino 1891 [synonym], Ortotherium schlosseri Ameghino 1891 [synonym], Ortotherium scrofum Bordas 1941 [synonym]

†Ortotherium robustum Ameghino 1881

G. †Paranabradys Scillato-Yané 1980

†Paranabradys vucetichae Scillato-Yané 1980

G. †Paraplanops Ameghino 1891

†Paraplanops oblongus Ameghino 1891

G. †Pattersonocnus Rincón et al. 2019

†Pattersonocnus diazgameroi Rincón et al. 2019

G. †Pliomorphus Ameghino 1885

†Pliomorphus mutilatus Ameghino 1885

Invalid names: Pliomorphus ameghinoi Kraglievich 1923 [synonym], Pliomorphus brevis Kraglievich 1923 [synonym]

†Pliomorphus robustus Ameghino 1885

G. †Protomegalonyx Kraglievich 1925

†Protomegalonyx chasicoensis Scillato-Yané 1977

†Protomegalonyx doellojuradoi Kraglievich 1925

†Protomegalonyx praecursor Kraglievich 1925

G. †Pseudhapalops Ameghino 1891

†Pseudhapalops altiramis Ameghino 1894

†Pseudhapalops forticulus Ameghino 1891

†Pseudhapalops grandis Ameghino 1894

†Pseudhapalops infernalis Ameghino 1887

†Pseudhapalops longitudinalis Ameghino 1891

†Pseudhapalops observationis Ameghino 1891

G. †Pseudortotherium Scillato-Yane 1981

G. †Torcellia Kraglievich 1923

†Torcellia paranense Kraglievich 1923

G. †Trematherium Ameghino 1887

†Trematherium nanum Ameghino 1891

G. †Urumacocnus Rincón et al. 2019

†Urumacocnus urbanii Rincón et al. 2019

G. †Xibalbaonyx Stinnesbeck et al. 2017

†Xibalbaonyx exinferis Stinnesbeck et al. 2020

†Xibalbaonyx microcaninus Stinnesbeck et al. 2018

†Xibalbaonyx oviceps Stinnesbeck et al. 2017

G. †Zacatzontli McDonald and Carranza-Castañeda 2017

†Zacatzontli cotobrusensis Valerio et al. 2022

†Zacatzontli tecolotlanensis McDonald and Carranza-Castañeda 2017

Invalid names: Choloepidae Gray 1871 [synonym]

Diagnosis

No diagnoses are available

Measurements

part	N	mean	median
DIstal Fibula height	1	28.5	-
Humerus height	2	80.0	80.0
Humerus diameter	2	170.0	170.0

Composition:

phosphaticsubp

Maximum body mass:

80 kgg

Minimum body mass:

40 kgg

Environment:

terrestrialsubc

Locomotion:

actively mobilec

Life habit:

ground dwellingf

Diet:

herbivoref

Reproduction:

viviparoussubc

Comments:

life habit and diet based on Nowak 1999f

Created:

2005-06-08 10:11:09

Modified:

2005-08-22 18:30:05

Source: g = genus, f = family, subc = subclass, c = class, subp = subphylum

References: Ji et al. 2002, Vizcaíno et al. 2010, Hendy et al. 2009, Carroll 1988, Nowak 1991, Lillegraven 1979

Age range

Maximum range based only on fossils: base of the Bartonian to the top of the Holocene or 41.30000 to 0.00000 Ma
Minimum age of oldest fossil (stem group age): 33.9 Ma

Collections (332 total)

Time interval	Ma	Country or state	Original ID and collection number
Oldest occurrences
Bartonian - Priabonian	41.3 - 33.9	Antarctica	Megalonychidae indet. (31173)
Deseadan	29.0 - 21.0	Bolivia	Megalonychidae indet. (95688)
Deseadan	29.0 - 21.0	Argentina (Mendoza)	Megalonychidae indet. (176466)
Deseadan	29.0 - 21.0	Bolivia (La Paz)	Megalonychidae indet. (133611)
Deseadan	29.0 - 21.0	Argentina (Santa Cruz)	Deseadognathus riggsi (220634)
Early/Lower Miocene	23.03 - 15.97	Cuba (Sancti Spiritus)	Imagocnus zazae (31183)
Miocene	23.03 - 5.333	USA (California)	Megalonychidae indet. (19376)
Colhuehuapian	21.0 - 17.5	Argentina (Chubut)	Megalonychidae indet., Hapaloides sp., Proschismotherium sp., Holomegalonyx sp. (141368)
Burdigalian	20.44 - 15.97	Chile (Magallanes)	Megalonychidae indet. (204203)
Burdigalian	20.44 - 15.97	Chile (Aisén)	Hapalops sp. (71843)
Burdigalian	20.44 - 15.97	Chile (Aysén)	Hapalops sp. (237483)
Burdigalian	20.44 - 15.97	Argentina (Santa Cruz)	Hapalops sp. (59319)
Burdigalian - Langhian	20.44 - 13.82	Colombia (Guajira)	Hyperleptus sp. (145271)
Santacrucian	17.5 - 16.3	Argentina (Santa Cruz)	Eucholoeops fronto (176563) Eucholoeops ingens (27313 176587 176643 207742) Eucholoeops sp. (176601) Eucholoeops sp., Hapalops sp. 1, Hapalops sp. 2, Hapalops sp., Eucholoeops ingens, Eucholaeops sp. 1 (142529) Eucholoeops sp., Hapalops sp., Eucholoeops fronto (176603) Eucholoeops sp., Hapalops sp., Pseudhapalops rutimeyeri (206241) Hapalops elongatus (176635 176641 207605 210638 210787) Hapalops indifferens, Hapalops elongatus, Hapalops angustipalatus, Eucholoeops fronto, Hapalops ponderosus (176585) Hapalops longiceps (176583) Hapalops platycephalus (176598) Hapalops sp. (176570 176571 176576 176592 176622 176623 176625 204358 210154) Hapalops sp. 1, Hapalops sp. 2 (176584) Hapalops sp. 1, Hapalops sp. 2, Eucholoeops fronto (176581) Hapalops sp., Hapalops gracilidens, Hapalops platycephalus (210153) Hapalops sp., Hapalops indifferens, Hapalops gracilidens, Pseudhapalops rutimeyeri, Megalonychotherium atavus (206237) Hapalops sp., Hapalops longiceps (176599) Hyperleptus sp. (176636) Hyperleptus sp., Hapalops sp. 1, Hapalops sp. 2, Eucholoeops ingens, Eucholoeops fronto, Eucholaeops sp. 1, Eucholaeops sp. 2 (142533) Hyperleptus sp., Hapalops sp., Eucholoeops ingens (176602) Megalonychidae indet., Hapalops sp. (87314) Megalonychidae indet., Hapalops sp., Hapalops elongatus (176590)
Santacrucian	17.5 - 16.3	Argentina (Buenos Aires)	Eucholoeops ingens (207743)
Santacrucian	17.5 - 16.3	Argentina (San Juan)	Hapalops sp. (197899)
Laventan	13.8 - 11.0	Bolivia (Tarija)	Pelecyodon sp. (38071)
Laventan	13.8 - 11.0	Peru (Ucayali)	Megalonychidae indet. (144793)
Laventan	13.8 - 11.0	Colombia	Hapalops sp. (13684 153817)
Laventan	13.8 - 11.0	Colombia (Huila)	Eucholoeops fronto (188252) Hapalops sp. (186628 186667 187122 187888 187961 187965 187974 187975) Hapalops sp., Megalonychinae indet. (187721) Megalonychidae indet. (13650 133441 186607 186621 186683 186860 187967 187972) Megalonychidae indet., Hapalops sp. (186630 187945) Megalonychinae indet. (133689 187078 187739)