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AMERICAN MUSEUM NOVITATES Number 3750, 36 pp. July 20, 2012 Two New Taxa (Caviomorpha, Rodentia) from the Early Oligocene Tinguiririca Fauna (Chile) ORNELLA C. BERTRAND,1 JOHN J. FLYNN,2 DARIN A. CROFT,3 AND ANDRE R. WYSS4 ABSTRACT Here we describe two new caviomorphs from the early Oligocene Tinguiririca Fauna of the Andean Main Range of central Chile, representing the most ancient rodents known from the mid to high latitudes of South America, and the second-oldest securely dated rodents from the continent. These two new taxa are each documented by single partial mandibles bearing largely complete dentitions. Representing two new taxa, Andemys termasi, gen. et sp. nov., and Eoviscaccia frassinettii, sp. nov., these caviomorphs are informally referred to the pan-Dasy- proctidae and pan-Chinchillidae, respectively. These taxa, together with recent findings in Peru, confirm that caviomorphs were well diversified prior to the Deseadan SALMA, that they likely originated during the middle to late Eocene, but that they did not spread from the tropics until some time after the Mustersan—a well-sampled interval from which rodents are unknown in higher latitudes. Additionally, in documenting the earliest occurrence of hypsodonty among caviomorphs Eoviscaccia frassinettii, sp. nov., provides important insights into the acquisition of this common mammalian dental innovation in rodents. 1 Laboratoire de Paléontologie, Institut des Sciences de l’Évolution, c.c. 64, Université Montpellier II, Place Eugène Bataillon, F-34095 Montpellier cedex 05, France; and Kade Fellow, Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79th St., New York, NY 10024. 2 Division of Paleontology and Richard Gilder Graduate School, American Museum of Natural History. 3 Department of Anatomy, Case Western Reserve University, Cleveland, OH 44106. 4 Department of Earth Science, University of California, Santa Barbara, CA 93106. Copyright © American Museum of Natural History 2012 ISSN 0003-0082 2 American Museum NOVitates NO. 3750 INTRODUCTION The early Oligocene Tinguiririca Fauna from the Andean main range of central Chile includes two new rodent taxa, both represented by partial mandibles (Flynn et al., 2003). We describe and name these taxa in this report. The sudden mid-Cenozoic appearance of caviomorphs in South America’s stratigraphic record is perplexing, given the continent’s geographic isolation at the time and the “African- Asian” distribution of the group’s nearest putative relatives, Phiomyidae and Baluchimyinae (Marivaux et al., 2000, 2002; Jaeger et al., 2010). The venerable notion of caviomorph mono- phyly (Wood and Patterson, 1959) has been corroborated repeatedly by molecular analyses (Nedbal et al., 1994; Huchon and Douzery, 2001; Opazo, 2005; Farwick et al., 2006; Poux et al., 2006; Huchon et al., 2007; Blanga-Kanfi et al., 2009; Churakov et al., 2010), but morphological evidence has remained more ambiguous. Auditory (Meng, 1990) and dental (Marivaux et al., 2004; Sallam et al., 2009) features have been interpreted as indicative of caviomorph mono- phyly, as has a recent combined molecular and morphological dataset (Horovitz et al., 2006). Nevertheless, a polyphyletic origin involving two independent colonizations has also been pro- posed on the basis of carotid arterial patterns and myology (Bugge, 1985; Woods and Herman- son, 1985; Bryant and McKenna, 1995; McKenna and Bell, 1998; Landry, 1999; Jenkins et al., 2005) and incisor enamel (Martin, 1994). With two exceptions (see discussion of the Santa Rosa and Contamana faunas below), rodents do not occur in or prior to the Mustersan (late middle and/or late Eocene) South American Land Mammal “Age” (SALMA). The group’s pres- ence in the high latitudes thus almost certainly postdates the Mustersan given the dense sam- pling of this and earlier SALMAs in the region (Vucetich et al., 1999; Madden et al., 2010), even for small-bodied taxa. Caviomorphs are widely inferred to have reached South America from Africa (Lavocat, 1974, 1976; Jaeger, 1989; Martin, 1994, 2005; Marivaux et al., 2004; Coster et al., 2010; Sallam et al., 2011), via one or more crossings of a ~1000–1500 km wide South Atlantic (Houle, 1999) during the Paleogene. An earlier alternative scenario, invoking dispersal from North America via the proto-Antilles (Wood and Patterson, 1959; Wood, 1968; 1972; 1974), was predicated on the now discredited (Hoffstetter and Lavocat, 1970; Bugge, 1985; Meng, 1990; Martin, 1994) notion of a close relationship between North American fra- nimorphs and Caviomorpha. An Asian origin for caviomorphs has been proposed on molecu- lar and morphological grounds (Hussain et al., 1978; Flynn et al., 1986; Jaeger, 1989; Huchon and Douzery, 2001). Nevertheless, dispersal between Asia and South America via North Amer- ica or Australia-Antarctica is contradicted by the lack of early Cenozoic hystricognaths in any of these locations (Hartenberger, 1985; Wood, 1985; Houle, 1999; Marivaux et al., 2002). South America’s isolation during most of the Cenozoic produced highly endemic land mam- mal faunas. Although this endemicity has hampered intercontinental biochronologic correlations, faunal changes have permitted recognition of a finely subdivided sequence of intracontinental biochronologic units. About 20 SALMAs spanning much of the Cenozoic are recognized (e.g., Simpson, 1940, 1950, 1980; Patterson and Pascual, 1968; Marshall et al., 1983; MacFadden, 1985; Marshall, 1985; Pascual and Ortiz Jaureguizar, 1990; Flynn and Swisher, 1995; Pascual et al., 1996; Flynn et al., 2003, 2012) (fig. 1). 2012 BERTRAND ET AL.: EARLY OLIGOCENE TINGUIRIRICA RODENTS 3 OLIGOCENE Simpson (1940) subdivided the Cenozoic mam- 25 malian record into three broad “faunal strata,” based Deseadan largely on the first appearance of various higher-level taxonomic groups. Simpson’s earliest subdivision (Stratum 1) is characterized by the first occurrences of 30 “archaic” lineages: Marsupialia, Xenarthra, and Tinguirirican endemic ungulates (e.g., certain “condylarths,” Litop- ? ? ? ? terna, Notoungulata). Faunal Stratum 2 is marked by immigration of caviomorph rodents and platyrrhine 35 ? ? ? ? primates, as well as by a “modernization” of the EOCENE Mustersan “archaic” lineages of Stratum 1, particularly various ? ? ? ? notoungulates. Simpson’s faunal Stratum 3 corre- 40 sponds to an interval spanning the late Miocene to Casamayoran Recent, i.e., the “Great American Biotic Interchange.” The base of Simpson’s faunal Stratum 2, tradition- ally the Deseadan SALMA (Simpson, 1948, 1950, 1967, 45 ? ? ? ? 1980), is marked by the first appearance of numerous clades, including—prior to discovery of the Tinguiririca Fig. 1. The transitional Eocene-Oligocene Fauna—caviomorphs. Deseadan caviomorphs are portion of the SALMA sequence (based on known from sequences in Patagonian Argentina Flynn and Swisher, 1995; as modified by Croft et al., 2008). (Ameghino, 1897, 1902; Loomis, 1914; Wood, 1949; Wood and Patterson, 1959; Vucetich, 1989), Bolivia (Hoffstetter and Lavocat, 1970; Lavocat, 1976; Patterson and Wood, 1982; Vuce- tich, 1989), Peru (Shockey et al., 2009), Uruguay (Kraglievich, 1932; Mones and Casti- glione, 1979), Brazil (Vucetich et al., 1994; Vucetich and Ribeiro, 2003) and Chile (unpub- lished). In addition to Tinguiririca, pre- Deseadan caviomorphs are also now reported from the Santa Rosa and Contamana faunas of Peru (Frailey and Camp- bell, 2004; Antoine et al., Fig. 2. Location map; Tinguiririca River valley, Termas del Flaco, Chile (mod- 2011). ified from Wyss et al., 1994). 4 TABLE 1. Oligocene and early Miocene caviomorphs used for comparisons in this study, with the proposed taxonomic placement of the two new taxa from the Tinguiririca Fauna (Chile) indicated. Superfamily Family Taxa Age Reference number Locality Dinomyidae Scleromys quadrangulatus Santacrucian MLP 82-VI-3-2 Santa Cruz Formation, Argentina Cavioidea Pan-Dasyproctidae Incamys bolivianus Deseadan PU 2093; PU 21952 Salla-Luribay Basin, Bolivia Neoreomys australis Santacrucian AMNH 9540; AMNH 9541-3 Santa Cruz Formation, Argentina - Colloncuran Branisamys luribayensis Deseadan PU 21944 Salla-Luribay Basin, Bolivia Australoprocta fleaglei Colhuehuapian MACN 1781; 1782; 1783; 1784; Gaiman (Chubut), Argentina A 1785; 1786; 1788; 1789 merican Dasyprocta punctata Extant AMNH 14179; AMNH 40831 Mexico, Ecuador, Venezuela, Colombia, Peru, Bolivia, Brazil, Paraguay, Argentina M Eoincamys pascuali ?Eocene and/or LACM 143299; 143306; 143308 Santa Rosa, Peru Oligocene useum Eobranisamys romeropittmanae ?Eocene and/or LACM 143342; 143345; 144293 Santa Rosa, Peru Oligocene N O Andemys termasi Tinguirirican SGOPV 2933 Tinguiririca V Eocardiidae Chubutomys simpsoni Deseadan AMNH 29557 Cabeza Blanca (Chubut), Argentina itates Octodontoidea Undetermined Draconomys verai Between MPEF-PV 7506 Gran Barranca, Argentina Deseadan and Tinguirirican Paulacoutomys paulista Deseadan MNRJ 4082-V Taubaté Basin, Brazil Sallamys pascuali Deseadan PU 20907; PU 20909 Salla-Luribay Basin, Bolivia Eosallamys simpsoni ?Eocene and/or LACM 143276; 143414 Santa Rosa, Peru Oligocene Eoespina woodi ?Eocene and/or LACM 143281; 143390; 144294 Santa Rosa, Peru Oligocene Eosachacui lavocati ?Eocene and/or LACM 143382; 143393 Santa Rosa, Peru N Oligocene O . 3750 . Deseadomys arambourgi Deseadan MNHN 1903-3-1 Cabeza Blanca (Chubut), Argentina 2012 Superfamily Family Taxa Age Reference number Locality Xylechimys obliquus Deseadan MLP 59-II-26–81 Cabeza Blanca (Chubut), Argentina