(Xenarthra, Mylodontidae) from the Pliocene of the Bolivia
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New well-preserved craniodental remains of Simomylodon uccasamamensis (Xenarthra, Mylodontidae) from the Pliocene of the Bolivian Altiplano: phylogenetic, chronostratigraphic, and paleobiogeographic implications Alberto Boscaini, Timothy Gaudin, Bernardino Mamani Quispe, Philippe Münch, Pierre-Olivier Antoine, Francois Pujos To cite this version: Alberto Boscaini, Timothy Gaudin, Bernardino Mamani Quispe, Philippe Münch, Pierre-Olivier An- toine, et al.. New well-preserved craniodental remains of Simomylodon uccasamamensis (Xenarthra, Mylodontidae) from the Pliocene of the Bolivian Altiplano: phylogenetic, chronostratigraphic, and pa- leobiogeographic implications. Zoological Journal of the Linnean Society, Linnean Society of London, 2019, 185 (2), pp.459-486. 10.1093/zoolinnean/zly075. hal-01922935 HAL Id: hal-01922935 https://hal.umontpellier.fr/hal-01922935 Submitted on 14 Dec 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Zoological Journal of the Linnean Society, 2018, XX, 1–28. With 15 figures. New well-preserved craniodental remains of 1.54 Simomylodon uccasamamensis (Xenarthra: Mylodontidae) 1.55 1.5 from the Pliocene of the Bolivian Altiplano: phylogenetic, chronostratigraphic and palaeobiogeographical AQ1 implications 1.60 1.10 ALBERTO BOSCAINI1* , TIMOTHY J. GAUDIN2, BERNARDINO MAMANI-QUISPE3, PHILIPPE MÜNCH4, PIERRE-OLIVIER ANTOINE5 and FRANÇOIS PUJOS1 1.65 1Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CCT-CONICET- 1.15 Mendoza, Avda. Ruiz Leal s/n, Parque Gral. San Martín, 5500 Mendoza, Argentina 2Department of Biology, Geology, and Environmental Science, University of Tennessee at Chattanooga, 615 McCallie Avenue, Chattanooga, TN 37403-2598, USA 3 Departamento de Palaeontología, Museo Nacional de Historia Natural de Bolivia, Calle 26 s/n, Cota 1.70 Cota, La Paz, Bolivia 1.20 4Géosciences Montpellier (UMR 5243, CNRS/UM), Université de Montpellier, Montpellier Cedex 05, France 5Institut des Sciences de l’Evolution de Montpellier, cc64, Université de Montpellier, CNRS, IRD, EPHE, F-34095 Montpellier, France 1.75 1.25 Received 1 May 2018; revised 17 August 2018; accepted for publication 7 September 2018 Fossil remains of extinct terrestrial sloths have been discovered in numerous localities throughout the Americas, but 1.80 knowledge of these animals remains poor in the tropical latitudes in comparison with the austral ones. Even where 1.30 Pliocene mylodontine sloths are known from North and South America, well-preserved craniodental remains are extremely rare, hindering reliable assessment of their taxonomic assignment and phylogenetic affinities. Here, new craniodental remains of Simomylodon uccasamamensis, from the latest Miocene–Pliocene of the Bolivian Altiplano, are described and compared with those of other Neogene Mylodontinae from South and North America. The resulting 1.85 morphological observations, combined with morphometric analyses, permit reliable differentiation among these mod- erate-sized Miocene–Pliocene mylodontids. Simomylodon uccasamamensis appears to be the smallest Pliocene mylo- 1.35 dontine, and it is closely related phylogenetically to the late Miocene species Pleurolestodon acutidens. Simomylodon uccasamamensis is also an endemic taxon of the Andean highlands during the Pliocene, with a continuous chrono- logical range extending throughout the Montehermosan, Chapdamalalan and (early) Marplatan South American Land Mammal Ages. This terrestrial sloth may have found its ideal ecological conditions in the Bolivian Altiplano, 1.90 during a span of time falling between the important South American Late Miocene–Pliocene faunal turnover and the 1.40 Great American Biotic Interchange around the Pliocene–Pleistocene transition. ADDITIONAL KEYWORDS: anatomy – Bolivian Altiplano – ‘ground’ sloth – Mylodontinae – phylogeny – Pliocene – Simomylodon uccasamamensis – Xenarthra. 1.95 1.45 INTRODUCTION represented by the genera Bradypus and Choloepus, ecologically and geographically restricted to tropical Extant sloths (Folivora = Tardigrada = Phyllophag rain forests of South and Central America. However, a; Delsuc et al., 2001; Fariña & Vizcaíno, 2003) are 1.100 the fossil record of sloths extends geographically 1.50 throughout the Americas and ranges chronologically *Corresponding author. E-mail: aboscaini@mendoza-conicet. from the late Eocene to the Holocene (e.g. Gaudin 1.52 gob.ar, [email protected] & Croft, 2015). Extinct sloths exhibit much greater 1.104 1 2 A. BOSCAINI ET AL. taxonomic diversity and morphological variation than The Neogene fossil record of mylodontines is scarce the extant forms, with ≥ 90 recognized genera (e.g. and, even though they range from South to North Mones, 1986; McKenna & Bell, 1997) displaying a America, the poor quality of the craniodental remains great variety of dietary habits and locomotor modes has often discouraged their inclusion in updated 2.60 2.5 (e.g. Bargo et al., 2006; Bargo & Vizcaíno, 2008; Pujos phylogenetic analyses. The Miocene mylodontines that et al., 2012; Toledo, 2016). Their abundance is concen- preserve a significant number of craniodental features trated especially in Argentina, southern Brazil and the are Glossotheriopsis pascuali Scillato-Yané, 1976, from USA, rather than in the tropics. However, this has long the Friasian, Colloncuran and Laventan SALMAs of been attributed to biases, owing to both the greater Argentina and Colombia (middle Miocene; Scillato- 2.65 2.10 accessibility of fossil-bearing deposits (i.e. more open Yané, 1976; McDonald, 1997) and Pleurolestodon acu- habitats) and the longer palaeontological tradition in tidens Rovereto, 1914, from the Huayquerian SALMA the countries that lie outside the tropical latitudes of Argentina (early Late Miocene; Rovereto, 1914). In of the American continent (Pujos et al., 2012, 2017; his pioneering work, Rovereto (1914) described three Rincón et al., 2016). Pleurolestodon species that were later synonymized by 2.70 2.15 Among Folivora, five monophyletic clades are rec- Kraglievich (1921) and Saint-André et al. (2010) under ognized and traditionally considered as families: the single species P. acutidens. The latter authors also Mylodontidae, Megalonychidae, Nothrotheriidae, established the new species Pleurolestodon dalenzae AQ3 Megatheriidae and Bradypodidae (e.g. Gaudin, 2004; Saint-André et al., 2010, on the basis of a single well- McDonald & De Iuliis, 2008; Slater et al., 2016). The preserved skull discovered in the late Neogene deposits 2.75 2.20 genus Pseudoglyptodon appeared in the late Eocene of the Choquecota section (Oruro Department, Bolivia; and is considered the oldest sloth, but its phylogen- Saint-André et al., 2010). In this work, the authors etic and familial affinities are still unknown; the also defined the new genus and species Simomylodon mylodontids and megalonychids are the first families uccasamamensis Saint-André et al., 2010 from the to radiate in South America, both represented by iso- Pliocene deposits of Ayo Ayo–Viscachani and Pomata- 2.80 2.25 lated late Oligocene remains (Pujos & De Iuliis, 2007; Ayte localities (La Paz and Oruro Departments, respect- McDonald & De Iuliis, 2008; Shockey & Anaya, 2011; ively, Bolivia; Saint-André et al., 2010). In the Pliocene, AQ4 Gaudin & Croft, 2015). The mylodontids persisted Glossotheridium chapadmalense (Kraglievich, 1925) until the late Pleistocene–earliest Holocene interval, is well represented in the Chapadmalalan SALMA of and three subfamilies are recognized by most authors: Argentina (Kraglievich, 1925; Cattoi, 1966). Remains 2.85 2.30 Mylodontinae, Lestodontinae and Scelidotheriinae (see tentatively assigned to the latter taxon were also iden- Pitana et al., 2013 and references therein). Additionally, tified in North America (Robertson, 1976) and Bolivia the subfamilies Octomylodontinae, Nematheriinae (Anaya & MacFadden, 1995). However, the specimens and Urumacotheriinae are considered valid by some from North America (including some scanty remains authors (e.g. Scillato-Yané, 1977; Rinderknecht et al., from Mexico) are now assigned to Paramylodon gar- 2.90 2.35 2010; Pitana et al., 2013), but their monophyly has never banii (Montellano-Ballesteros & Carranza-Castañeda, been demonstrated. Consequently, the Scelidotheriinae, 1986; Morgan, 2008; McDonald & Morgan, 2011). Mylodontinae and Lestodontinae remain the only During the Pliocene, mylodontid terrestrial sloths widely accepted mylodontid subfamilies. According to were widely spread in the Americas. As recent dis- Gaudin (2004), these three clades are monophyletic, but coveries testify, early members of the clade occupied 2.95 2.40 Lestodontinae represents a subgroup of Mylodontinae, the central and northern areas of South America in thus constituting the tribe Lestodontini. The lat- the late Oligocene–early Miocene (Shockey & Anaya, ter usage is followed here for the clade comprising 2011; Rincón et al., 2016). This suggests that atten- Lestodon and Thinobadistes. Following the same au- tion should be paid to poorly