Abstract
The presence of osteoderms in the skin of some extinct sloths and in cingulates (armadillos, pampatheres, and glyptodonts) has often been considered a pleisomorphic character of the Xenarthra. While osteoderms are known from the earliest cingulates, they are absent in most sloths including the two extant taxa and only appear late in their fossil record. Osteoderms are currently only reported from five genera of mylodonts and two megatheres, out of the over 100 currently recognized genera of sloths. Consequently, rather than a plesiomorphic character of the Xenarthra, which has been secondarily lost in sloths, it is more likely that osteoderms in sloths are the result of parallel evolution to the cingulates that independently evolved in one, possibly two different sloth clades.
This is a preview of subscription content, access via your institution.




Abbreviations
- NALMA:
-
North American Land Mammal Age
- SALMA:
-
South American Land Mammal Age
- ABDSP(LACM):
-
Anza Borrego Desert State Park, Borrego Springs, California (specimen originally in the Natural History Museum of Los Angeles County)
- FMNH:
-
Field Museum of Natural History, Chicago, Illinois
References
Allen GM (1913) A new Mylodon. Memoirs of the Museum of Comparative Zoology at Harvard College 40:319-346
Ameghino F (1887) Enumeración sistemática de las especies de mamíferos fósiles coleccionados por Carlos Ameghino en los terrenos eocenos de la Patagonia austras y depositados en el Museo La Plata. Boletim Museo La Plata 1:1-26
Ameghino F (1907) Notas sobre una pequeña colección de huesos de mamíferos procedentes de las grutas calcáreas de Iporanga en el Estado de São Paulo, Brasil. Revista do Museu Paulista 7:59-124
Arzani H, Lanzelotti SL, Acuña Suárez GE, Novo NM (2014) Primer registro de pelos fósiles en Glossotherium robustum (Xenarthra, Mylodontidae), Pleistoceno tardío, Mercedes, Provincia de Buenos Aires, Argentina. Ameghinana 51:585-590
Bargo MS, Toledo N, Vizcaíno SF (2012) Paleobiology of the Santacrucian sloths and anteaters (Xenarthra, Pilosa). In: Vizcaíno SF, Kay RF, Bargo MS (eds) Early Miocene Paleobiology in Patagonia. Cambridge University Press, pp 216-242
Bergqvist LP, Abrantes ÉPL, Avilla LDS (2004) The Xenarthra (Mammalia) of Sao José de Itaboraı Basin (upper Paleocene, Itaboraian), Rio de Janeiro, Brazil. Geodiversitas 26:323-337
Boule M, Thévenin (1920) Mammifères fossils de Tarija. Librairie H. le Soudier, Paris, 256 pp
Branco W (1906) Die Anwendung der Röntgenstrahlen in der Paläontologie. Abhandlungen der Königlich Preussischen Akademie der Wissenschaften Berlin:1-55
Burmeister H (1867) Fauna Argentina. I. Mamiferos fósiles. Lista de los mamiferos fósiles del terreno diluviano. Anales del Museo Público de Buenos Aires 1:87-300
Carlini AA, Ciancio MR, Flynn JJ, Scillato-Yané GJ, Wyss AR (2009) The phylogenetic and biostratigraphic significance of new armadillos (Mammalia, Xenarthra, Dasypodidae, Euphractinae) from the Tinguirirican (early Oligocene) of Chile. J Syst Palaeontol 7:489-503
Carranza-Castañeda O (2006) Late Tertiary fossil localities in central Mexico, between 19°-23°N. In: Carranza-Castañeda O, Lindsay EH (eds) Advances in Late Tertiary Vertebrate Paleontology in Mexico and the Great American Biotic Interchange. Universidad Nacional Autónoma de México, Instituto de Geología and Centro de Geociencias, Publicación. Especial 4:45-60
Cartelle C (1991) Um novo Mylodontinae (Edentata, Xenarthra) do Pleistoceno final de região intertropical brasileira. An Acad Bras Ciênc 63:161-170
Cartelle C, Bohórquez GA (1986) Presença de ossículos dérmicos em Eremotherium laurillardi (Lund) Cartelle & Bohorquez, 1982. (Edentata, Megatheriidae). Iheringia 11:3-8
Cartelle C, De Iuliis G (1995) Eremotherium laurillardi: the Panamerican late Pleistocene megatheriid sloth. J Vertebr Paleontol 15:830-841
Cartelle C, Fonseca S (1983) Contribuição ao melhor conhecimento da pequeña preguiça terrícola Nothrotherium maquinense (Lund) Lydekker, 1998. Lundiana 2:127-181
Cattoi N (1962) Un nuevo (Xenarthra) del Terciario de Patagonia, Chubutherium ferelloii gen. et. sp. nov. (Megalonychoidea, Mylodontidae). Revista Museo Argent Ciencias Nacional “Bernardino Rivadavia” Zool 8:123-133
Ciancio MR, Krmpotic CM, Scarano AC, Epele MB (In Press) Internal morphology of osteoderms of extinct armadillos and its relationship with environmental conditions. Journal of Mammalian Evolution
Collins RL (1933) Mylodont (ground sloth) dermal ossicles from Colombia, South America. J Wash Acad Sci 23:426-429
Dechaseaux C (1971) Oreomylodon wegneri, édenté gravigrade du Pléistocène de l'Equateur - Crâne et moulage endocrânien. Ann Paléontol 57:243-285
Delsuc F, Catzeflis FM, Stanhope M J, Douzery EJP (2001) The evolution of armadillos, anteaters and sloths depicted by nuclear and mitochondrial phylogenies: implications for the status of the enigmatic fossil Eurotamandua. Proc Roy Soc B 268:1605-1615
Dilkes DW, Reisz RR (1996) First record of a basal synapsid (‘mammal-like reptile’) in Gondwana. Proc Roy Soc Lond B 263:1165-1170
Gaudin TJ (2004) Phylogenetic relationships among sloths (Mammalia, Xenarthra, Tardigrada): the craniodental evidence. Zool J Linn Soc 140:255-305
Graham RW, Kay M (1988) Taphonomic comparisons of cultural and noncultural faunal deposits at the Kimmswick and Barnhart Sites, Jefferson County, Missouri. In: Laub RS, Miller NG, Steadman DW (eds) Late Pleistocene and Early Holocene Paleoecology and Archeology of the Eastern Great Lakes Region. Bulletin of the Buffalo Society of Natural Science 33:227-240
Hill RV (2006) Comparative anatomy and histology of xenarthran osteoderms. J Morphol 267:1441-1460
Hirschfeld SE (1985) Ground sloths from the Friasian La Venta fauna, with additions to the Pre-Friasian Coyaima fauna of Colombia, South America. Univ Calif Publ Geol Sci 128:1-91
Hoffstetter R (1952) Les mammifères Pléistocènes de la République de L’Équateur. Mémoires de la Société Géologique de France 66:1-391
Kraglievich L (1925) Cuatro nuevos gravigrados de la Araucana chapadmalense. Anales del Museo Nacional de Historia Natural de Buenos Aires 33:215-235
Krmpotic CM, Ciancio MR, Barbeito C, Mario RC, Carlini AA (2009) Osteoderm morphology in recent and fossil euphractine xenarthrans. Acta Zool 90:339-351
Krmpotic CM, Carlini AA, Galliari FC, Favaron P, Miglino MA, Scarano AC, Barbeito CG (2014) Ontogenetic variation in the stratum granulosum of the epidermis of Chaetophractus vellerosus (Xenarthra, Dasypodidae) in relation to the development of cornified scales. Zoology117:392-397
Lönnberg E (1899) On some remains of “Neomylodon listai” Ameghino brought home by the Swedish Expedition to Tierra del Fuego 1895-1897. Svenska Expeditionen Till Magellansländerna 2:149-170
López-Mendoza P, Mena-Larraín F (2011) Extinct ground sloth dermal bones and their role in the taphonomic research of caves: the case of Baño Nuevo-1 (Andean Central Patagonia, Chile). Revista Mexicana de Ciencias Geológicas 28:519-532
Lund PW (1840) Blik paa Brasiliens Dyreverden för Sidste Jordomvaeltning. Tredie. Afhandling. Fortseattelse af Pattedyrene. Det Kongelige Danske Videnskabernes. Selskabs Naturvidenskabr\elige og Mathematiske Afhandlinger 8:217-272
McAfee RK (2009) Reassessment of the cranial characters of Glossotherium and Paramylodon (Mammalia: Xenarthra: Mylodontidae). Zool J Linn Soc 155:885-903
McDaniel GE Jr, Jefferson GT, McDonald HG (2001) A large Paramylodon harlani osteoderm layer from the Irvingtonian of Anza-Borrego Desert State Park, California. J Vertebr Paleontol 21:79A
McDonald HG (1997) Xenarthrans: Pilosans. In: Kay RF, Madden RH, Cifelli RL, Flynn JJ (eds) Vertebrate Paleontology in the Neotropics: The Miocene Fauna of La Venta, Colombia. Smithsonian Institution Press, Washington, D.C., pp 231-243
McDonald HG, Vizcaíno SF, Bargo MS (2008) Fossil vermilinguas – an overview. In: Vizcaíno SF, Loughry J (eds) The Biology of the Xenarthra. University of Florida Press, Gainesville, pp 64-78
McKenna MC, Bell SK (1997) Classification of Mammals Above the Species level. Columbia University Press, New York
Merriam JC (1908) Death trap of the ages. Sunset Magazine 21:465-475
Montellano M, Carranza-Castañeda O (1981) Edentados Pliocenicos de la region central de Mexico. Anais II Congresso Latino-Americano Paleontologia, Porto Alegre:683-695
Montellano-Ballesteros M, Carranza-Castañeda O (1986) Descripción de un milodontido del Blancan temprano de la mesa central de Mexico. Universidad Nacional Autónoma de México, Instituto de Geología Revista 6:193-203
Moreno FP, Woodward AS (1899) On a portion of mammalian skin, named Neomylodon listai, from a Cavern near Consuelo Cove, Last Hope Inlet, Patagonia. Proc Zool Soc Lond 67:144-156
Oliveira EV, Bergqvist LP (1998) A new Paleocene armadillo (Mammalia, Dasypodoidea) from the Itaboraí Basin, Brazil. Paleógeno de América del Sur y de la Península Antártica. Asociación Paleontológica Argentina, Publicación Especial 5:35-40
Perea D (1992) Aproximacion a la sistematica filogenetica de Mylodontinae (Xenarthra). Boletín de la Sociedad Zoológica del Uruguay 7:33-34
Politis GG, Messineo PG (2008) The Campo Laborde site: new evidence for the Holocene survival of Pleistocene megafauna in the Argentine Pampas. Quaternary Internatl 191:98-114
Pujos F, De Iuliis G (2007) Late Oligocene Megatherioidea fauna (Mammalia: Xenarthra) from Salla-Luribay (Bolivia): new data on basal sloth radiation and Cingulata-Phyllophaga split. J Vertebr Paleontol 27:132-144
Reisz RR, Modesto SP (2007) Heleosaurus scholtzi from the Permian of South Africa: a varanopid synapsid, not a diapsid reptile. J Vertebr Paleontol 27:734-739
Rinderknecht A (2002) La presencia de osteodermos en las extremidades posteriores de Glyptodon clavipes Owen, 1839 (Mammalia: Cingulata). Ameghiniana 37:369-373
Robertson JS (1976) Latest Pliocene mammals from Haile XVA, Alachua County, Florida. Bull Florida St Mus - Biol Sci 20:111-186
Romer AS (1966) Vertebrate Paleontology. 3rd Edition. University of Chicago Press, Chicago
Scott WB (1903–1904) Mammalia of the Santa Cruz beds. Part 1: Edentata. Report of the Princeton Expeditions to Patagonia 5:1-364
Shuler EW (1918) The geology of Dallas County. University of Texas Bulletin 1818:1-54
Sinclair WJ (1910) Dermal bones of Paramylodon from the asphaltum deposits of Rancho La Brea, near Los Angeles, California. Proc Am Phil Soc 49:191-195
Stock C (1925) Cenozoic gravigrade edentates of western North America with special reference to the Pleistocene Megalonychidae and Mylodontidae of Rancho La Brea. Carnegie Instit Wash Publ 331:1-206
Vickaryous MK, Hall BK (2006) Osteoderm morphology and development in the nine-banded armadillo, Dasypus novemcinctus (Mammalia, Xenarthra, Cingulata). J Morphol 267(11):1273-1283
Vickaryous MK, Hall BK (2008) Development of the dermal skeleton in Alligator mississippiensis (Archosauria, Crocodylia) with comments on the homology of osteoderms. J Morphol 269:398-422
Villarroel CA (1998) Los Nothrotheriinae (Megatheriidae, Gravigrada) del Mioceno de La Venta (Colombia). Descripción de Huilabradys magdaleniensis, nuevos genero y especie. Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales 22:497-506
Villarroel C (2000) Un nuevo Mylodontinae (Xenarthra, Tardigrada) en la fauna de La Venta, Mioceno de Colombia: el estado actual de la familia Orophodontidae. Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales 24:117-127
Wolf D, Kalthoff DC, Sander PM (2012) Osteoderm histology of the Pampatheriidae (Cingulata, Xenarthra, Mammalia): implications for systematics, osteoderm growth, and biomechanical adaptation. J Morphol 273:388-404
Woodward AS (1899) On some remains of Grypotherium (Neomylodon) listai and associated mammals from a cavern near Consuelo Cove, Last Hope Inlet, Patagonia. Proc Zool Soc Lond 69:64-78
Yané GJS (2013) Notas sobre los Dasypodidae (Mammalia, Edentata) del Plioceno del Territorio Argentino I. Los restos de edad Chasiquense (Plioceno Inferior) del sur del provincial de Buenos Aires. Ameghiniana 14:133-144
Acknowledgements
Bill Simpson kindly provided the images of the mylodont osteoderms from Tarija at the Field Museum of Natural History, Chicago. John Simmons kindly provided the photos of the mummified skin of Mylodon darwinii housed at the Natural History Museum, London, which granted permission to use the images. I thank the three anonymous reviewers for their comments and suggestions.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
McDonald, H.G. An Overview of the Presence of Osteoderms in Sloths: Implications for Osteoderms as a Plesiomorphic Character of the Xenarthra. J Mammal Evol 25, 485–493 (2018). https://doi.org/10.1007/s10914-017-9415-8
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10914-017-9415-8