Superregnum: Eukaryota
Cladus: Orthokaryota
Cladus: Neokaryota
Cladus: Scotokaryota
Cladus: Podiata
Cladus: Amorphea
Cladus: Obazoa
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: ParaHoxozoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Olfactores
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Cladus: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Cladus: Synapsida
Cladus: Eupelycosauria
Cladus: Metopophora
Cladus: Haptodontiformes
Cladus: Sphenacomorpha
Cladus: Sphenacodontia
Cladus: Therapsida
Cladus: Theriodontia
Cladus: Eutheriodontia
Cladus: Cynodontia
Cladus: Epicynodontia
Cladus: Eucynodontia
Cladus: Probainognathia
Cladus: Prozostrodontia
Cladus: Mammaliamorpha
Cladus: Mammaliaformes
Classis: Mammalia
Cladus: Theriimorpha
Cladus: Theriiformes
Cladus: Trechnotheria
Cladus: Cladotheria
Cladus: Prototribosphenida
Cladus: Zatheria
Cladus: Tribosphenida
Cladus: Boreosphenida
Subclassis: Theria
Cladus: Eutheria
Infraclassis: Placentalia
Superordo: Xenarthra
Ordo: Pilosa
Subordo: Folivora
Familia: †Megatheriidae
Subfamilia: Schismotheriinae
Genus: Hapalops
Species: H. indifferens – H. longicers – H. longipes – H. latus – H. cadens – H. congermanus – H. gallaicus – H. ruetimeyeri
Name
Hapalops Ameghino, 1887
Hapalops is an extinct genus of ground sloth from the Early to Late Miocene of Brazil (Solimões Formation), Bolivia (Honda Group), Colombia (Honda Group),[1] and Argentina (Santa Cruz Formation) in South America.[2]
History
Hapalops was first described by notable Argentine paleontologist and zoologist Florentino Ameghino in 1887, with his description of H. rectangularis as the type species. It was erected based on the posterior part of a left dentary that had been collected from the Miocene aged deposits of Santa Cruz, Argentina, though Ameghino also described a second partial mandible from the same deposits as part of the species, making it a paratype. All of these fossils have been lost and their fragmentary status puts the validity of the genus as a whole in jeopardy.[3]
Description
Sloths in this genus had a long, robust body with more than 19 thoracic vertebrae, a short skull, and long limbs with large, curved claws. They were small sloths, measuring about 1 metre (3.3 ft) in length. On the ground, they probably walked on the knuckles of the forelimbs, like a gorilla. Hapalops had very few teeth with no incisors; the mandible included only four pairs of teeth.[4]
Paleobiology
In the Santa Cruz, Hapalops fed on vegetation in intertropical wooded savannahs. It shared its environment with both herbivorous and predatory marsupials, sheep-sized glyptodonts, armadillos, anteaters, toxodonts, typotheres, and litopterns, as well as modern reptiles such as iguanas and birds such as rheas, geese, and hawks. Giant phorusrachid "terror birds" lived in the region and may have been the top predators.[5] Like most extinct sloths it is categorized as a ground sloth, but it is believed that the smaller size of Hapalops allowed it to engage in some climbing behaviors.[6]
Classification
The genus is classified within the Megatherioidea, which includes the megalonychid and the nothrotheriid sloths. While it is generally represented as an outgroup to Nothrotheriidae and a genus of uncertain relationships, it shows most of the character states that diagnose Nothrotheriidae and may be a close relative. At least 26 species in this genus have been named from the same Santa Cruz formation, a biological impossibility largely based on assigning new species names to fossil fragments. The genus awaits revision.[7]
References
iconMammals portaliconPaleontology portal
Croft, 2007, p.300
Hapalops at Fossilworks.org
Bargo, M. S., De Iuliis, R., & Toledo, N. (2019). "Early Miocene sloths (Xenarthra, Folivora) from the Río Santa Cruz valley (Southern Patagonia, Argentina)". Ameghino, 1887 revisited. Early–Middle Miocene Paleontology in the Río Santa Cruz, Southern Patagonia, Argentina, 130, 102–137.
Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 207. ISBN 978-1-84028-152-1.
Farina, Richard A, Sergio F. Vizcaino, and Gerry de Iuliis (2013). Megafauna; Giant Beasts of Pleistocene South America. Bloomington: Indiana University Press. ISBN 9780253002303.
White, J. 1993. "Indicators of locomotor habits in Xenarthrans: Evidence for locomotor heterogeneity among fossil sloths". Journal of Vertebrate Paleontology, 13(2): 230–242
Pujos, François; De Iuliis, Gerardo; Quispe, Bernardino Mamani (September 2011). "Hiskatherium saintandrei, gen. et sp. nov.: an unusual sloth from the Santacrucian of Quebrada Honda (Bolivia) and an overview of middle Miocene, small megatherioids". Journal of Vertebrate Paleontology. 31 (5): 1131–1149. Bibcode:2011JVPal..31.1131P. doi:10.1080/02724634.2011.599463. ISSN 0272-4634. S2CID 86755668.
Bibliography
Croft, Darin A (2007). "The Middle Miocene (Laventan) Quebrada Honda Fauna, southern Bolivia and a description of its Notoungulates". Palaeontology. 50 (1): 277–303. Bibcode:2007Palgy..50..277C. doi:10.1111/j.1475-4983.2006.00610.x. S2CID 140161482.
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