First record of Toxodontidae (Mammalia, Notoungulata) from the late Miocene–early Pliocene of the southern central Andes, NW Argentina

Abstract

Abstract.-A new species of toxodontid notoungulate, Xotodon maimarensis n. sp., is described from the Maimará Formation (late Miocene-early Pliocene), Jujuy Province, northwestern Argentina. This is the first record of a toxodontid from the Eastern Cordillera. The specimen is housed at the Museo de Geología, Mineralogía y Paleontología, Instituto de Geología y Minería de la Universidad Nacional de Jujuy. It consists of an incomplete mandible preserving the right mandibular ramus with part of the dental series, partially preserved symphysis with all the incisors, and a small portion of the left ramus without teeth. The following characters distinguish it as a new taxon: symphysis long and narrow with slight divergence of its lateral borders; strong procumbence of lower incisors and deeply implanted i3; chin angle lower than in X. major and X. cristatus and bulging labial keel limiting strong lateral concavities. Comparative analysis in the context of the recently revised Neogene Toxodontidae indicates that the Maimará specimen shares mandibular features and dental characters with Xotodon and Mixotoxodon, differing from the latter by the more upraised symphysis. The phylogenetic position of Xotodon maimarensis n. sp. supports the taxonomic interpretation of the studied specimen as a new species of Xotodon. This new Toxodontidae increases the knowledge of the diversity and radiation of this group of notoungulates in northwest Argentina.

New records of Neogene Xenarthra (Mammalia) from eastern Puna (Argentina): diversity and biochronology

“…Macrochorobates scalabrinii has been recorded in the Andalhuala Formation, Catamarca Province (Marshall and Patterson, 1981; Bossi et al, 1987; Esteban and Nasif, 1996; Esteban et al, 2001). Radiometric dating for this unit estimated the age to be between 7.14 and 5.59 Ma (Marshall and Patterson, 1981; Latorre et al, 1997; Reguero and Candela, 2011; Bonini et al, 2017). This species has also been cited for the Epecuén Formation (Huayquerian SALMA), Buenos Aires Province (Scillato-Yané, 1980, 1982); Cerro Azul Formation (Huayquerian SALMA), La Pampa Province (Esteban et al, 2001; Urrutia et al, 2008); Salicas Formation, La Rioja Province (Tauber, 2005; Brandoni et al, 2012); and Las Flores Formation, San Juan Province (Contreras, 2007; Contreras et al, 2013) in which the fossil-bearing level is between 6.9 and 6.3 Ma (Ré et al, 2003).…”

“…Most knowledge of the evolutionary history of Xenarthra comes from southern South America (Carlini et al, 2005; Croft et al, 2016), but knowledge of the group from middle and low latitudes has recently increased (Cozzuol, 2006; Ciancio et al, 2013; Tejada-Lara et al, 2015; Amson et al, 2016; Antoine et al, 2016), including Andean and sub-Andean areas (Croft et al, 2004, 2007, 2009, 2016; Reguero and Candela, 2008, 2011; Contreras et al, 2013; Bonini et al, 2017). Particularly between 30°S and 15°S, several authors have reported numerous Neogene localities bearing abundant paleofaunas (some of them from elevations of > 2500 masl) in which xenarthrans are one of the best-represented groups.…”

“…The Argentine Province of Jujuy has one of the most important continental late Miocene–Pleistocene sequences of South America, in areas currently near 2700 masl (Pingel et al, 2012). More precisely in the Quebrada de Humahuaca (Eastern Cordillera), the localities of Uquía, Esquina Blanca, Chucalezna, San Roque, and Maimará (Salfity et al, 1984; Reguero et al, 2007; Reguero and Candela, 2008, 2011; Pingel et al, 2012; Pujos et al, 2012; Abello et al, 2015; Galli et al, 2016; Bonini et al, 2017) have yielded a large diversity of vertebrates in which xenarthrans are well represented (Reguero and Candela, 2008, 2011; Pujos et al, 2012).…”

The Neogene Record of Northern South American Native Ungulates

“…Abbreviations: SM = Stratigraphic meter; Lat = latitude; Lon = longitude. Basin Bonini et al (2017a) topologies but their positions are different in the cladograms. Concerning the toxodontinaes from northern South America, the main difference in our result is that the toxodontids recorded in Venezuela (Mixotoxodon, Gyrinodon, and Falcontoxodon) form a monophyletic group (node 45) and belong to a clade that also includes Piauhytherium (node 46; Figure 24a).…”

“…We performed a maximum parsimony analysis on 28 notoungulate taxa and 59 morphological characters with PAUP* 4.0 (Swofford, 2002). We used the matrix presented by Forasiepi et al (2015) and modified by Bonini et al (2017a). We added Piauhytherium as described by Guérin and Faure (2013), and the new toxodontine from Codore Formation.…”