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New Toxodontid (Notoungulata) from the Early Miocene of Mendoza, Argentina

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RESEARCH PAPER New toxodontid (Notoungulata) from the Early Miocene of Mendoza, Argentina Analı´a M. Forasiepi • Esperanza Cerden˜o • Mariano Bond • Gabriela I. Schmidt • Maximiliano Naipauer • Fiona R. Straehl • Agustı´n G. Martinelli • Alberto C. Garrido • Mark D. Schmitz • James L. Crowley Received: 21 November 2013 / Accepted: 12 May 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract We describe a new toxodontid species, Nes- dental features, and close comparisons were made with the odon taweretus sp. nov., from the Aisol Formation in Patagonian Nesodon imbricatus, common in the Santa Cruz Mendoza Province, central-west Argentina. Nesodon is a Formation (Santacrucian Age, Early Miocene). The mate- frequently found Toxodontidae, member of the Noto- rial is of a similar size to N. imbricatus, with a body mass ungulata, an extinct endemic group of Cenozoic South estimation of about 550 kg. The phylogenetic analysis American mammals that are ecologically similar to current groups N. taweretus sp. nov. with other species of Nesodon. hoofed ungulates. The holotype of N. taweretus sp. nov. is The absolute age of the Aisol Formation has been estab- a skull, and we tentatively assign some mandibular frag- lished at ca 19.480 ± 0.025 Ma (Burdigalian; Early Mio- ments and postcranial bones. N. taweretus sp. nov. differs cene) by means of U–Pb zircon dating. The vertebrate from the other Nesodon species in several cranial and association is encompassed by the Santacrucian Age. Lat- itudinal separation between Mendoza and Patagonia in the south would have favored taxonomic differences, as Electronic supplementary material The online version of this reflected in the species of Nesodon. article (doi:10.1007/s12542-014-0233-5) contains supplementary material, which is available to authorized users. A. M. Forasiepi (&) Á E. Cerden˜o M. Naipauer Paleontologı´a, IANIGLA, CCT-CONICET Mendoza, Instituto de Estudios Andinos ‘‘Don Pablo Groeber’’ (FCEyN, Av. Ruiz Leal s/n, 5500 Mendoza, Argentina Universidad de Buenos Aires-CONICET), Pab. 2, Ciudad e-mail: [email protected] Universitaria, C1428EHA Buenos Aires, Argentina e-mail: [email protected] E. Cerden˜o e-mail: [email protected] A. G. Martinelli Departamento de Paleontologia e Estratigrafia, Instituto de A. M. Forasiepi Á F. R. Straehl Geocieˆncias, Universidade Federal do Rio Grande do Sul, Ave. Pala¨ontologisches Institut und Museum, Bento Gonc¸alves, 9500, Porto Alegre, RS 91540-000, Brazil Universita¨tZu¨rich, Karl Schmid-Strasse 4, 8006 Zurich, e-mail: [email protected] Switzerland e-mail: fi[email protected] A. C. Garrido Museo Provincial de Ciencias Naturales ‘‘Profesor Dr. Juan A. M. Bond Olsacher’’, Etcheluz y Ejercito Argentino, 8340 Zapala, Divisio´n Paleontologı´a de Vertebrados, Museo de La Plata, Neuque´n, Argentina Paseo del Bosque s/n, B1900 La Plata, Buenos Aires, Argentina e-mail: [email protected] e-mail: [email protected] M. D. Schmitz Á J. L. Crowley G. I. Schmidt Boise State University, 1910 University Drive, Boise, Laboratorio de Paleontologı´a de Vertebrados, Centro de ID 83725-1535, USA Investigaciones Cientı´ficas y Transferencia de Tecnologı´aala e-mail: [email protected] Produccio´n (CICYTTP-CONICET), Materi y Espan˜a, 3105 Diamante, Entre Rı´os, Argentina J. L. Crowley e-mail: [email protected] e-mail: [email protected] Keywords Nesodon Á South America Á Cenozoic Á Early Mendoza Province has been the subject of new pale- Miocene Á U–Pb (CA-ID-TIMS) tuff age ontological studies in the last few years, with a great deal of information on the evolution and distribution of Ceno- Kurzfassung Wir beschreiben eine neue Art der Tox- zoic mammals coming to light (Cerden˜o 2011). One of the odontiden, Nesodon taweretus sp. nov., aus der Aisol- areas studied and prospected is the Aisol Formation out- Formation in der Provinz Mendoza, im Zentralwesten von cropping in the San Rafael Department, in the center of the Argentinien. Nesodon ist ein ha¨ufig vorkommendes Taxon province (Fig. 1a) (Forasiepi et al. 2009, 2011; Vucetich der Toxodontidae, die zu den Notoungulaten, einer et al. 2011). The Aisol Formation outcrops in isolated ausgestorbenen Gruppe von endemischen Sa¨ugetieren des deposits that are exposed on the San Rafael Block and Ka¨nozoikums in Su¨damerika, geho¨ren und den rezenten mainly associated with the Atuel and Diamante rivers gehuften Ungulata o¨kologisch a¨hnlich waren. Der Holotyp (Dessanti 1954, 1956; Gonza´lez Dı´az 1972; Sepu´lveda von N. taweretus sp. nov. ist ein Scha¨del, dem wir vorla¨ufig et al. 2001, 2007). Several fossiliferous localities have been einige Unterkieferfragmente und postkraniale Knochen found in the area, with the richest being the Arroyo Seco de zuweisen. N. taweretus sp. nov. unterscheidet sich von den la Frazada (Fig. 1a). The stratigraphy of the Aisol For- anderen Nesodon-Arten in mehreren Merkmalen des mation has been subject of recent revisions (Forasiepi et al. Scha¨dels und der Bezahnung. Enge Vergleiche wurden mit 2011). Here, the Aisol Formation corresponds to the lower dem aus Patagonien stammenden und in der Santa-Cruz- section (LS) described by Forasiepi et al. (2011; Fig. 1b). Formation (Santacruzium, fru¨hes Mioza¨n) verbreiteten The fossil vertebrate association includes Anura, Testudi- Nesodon imbricatus gemacht. Das Material ist von a¨hnlicher ninae, Xenarthra, Notoungulata, Litopterna, and Rodentia Gro¨sse wie N. imbricatus,Scha¨tzungen der Ko¨rpermasse (Forasiepi et al. 2011). To date, the chronology of the Aisol ist etwa 550 kg. Die phylogenetische Analyse gruppiert Formation has been controversial. Early authors suggested N. taweretus sp. nov. mit anderen Arten von Nesodon. Das that the unit was deposited during the late Early Miocene absolute Alter der Aisol-Formation wurde mittels der U–Pb (Santacrucian Age; Dessanti 1954, 1956; Gonza´lez Dı´az Zirkondatierung auf etwa 19.480 ± 0.025 Ma (Burdigalium, 1972). Later fossil mammal finds suggested a middle Unteres Mioza¨ns) gesetzt. Die Wirbeltiervergesellschaftung Miocene age (Friasian s.l. sensu Soria 1983 or Colloncuran in das Santacruzium eingeschlossen worden. Latitudinale sensu Forasiepi et al. 2011). This contribution presents a Trennung zwischen Mendoza und Patagonien im Su¨den ha¨tte new radiometric dating of a 19.480 ± 0.025 Ma tuff bed, taxonomischen Unterschiede begu¨nstigt, wie das anhand der which constrains the absolute age of the mammalian Arten von Nesodon widergegeben ist. assemblage at these latitudes to the Early Miocene. The Notoungulata is a diverse and abundant clade of Schlu¨sselwo¨rter Nesodon Á Su¨damerika Á Ka¨nozoikum Á extinct South American ungulates recorded from the fru¨hes Mioza¨n Á U–Pb (CA-ID-TIMS) Tuff Datierung Paleocene to the Pleistocene (Bond et al. 1995; Bond 1999). Following the formation of the Panama Bridge, the distribution of the group increased from South America to Introduction Central and North America (Polaco et al. 2004; Lundelius et al. 2013). Their phylogenetic affinities are still unclear. For more than a century, Patagonia in Southern Argentina Notoungulates were related to other South American native has provided rich fossil localities for the study of Cenozoic ungulates (Astrapotheria, Litopterna, Pyrotheria, and Xe- mammals. Age calibrations, coupled with the quality and nungulata) in the group Meridiungulata (McKenna 1975). the quantity of the Patagonian fossil record, provide However, recent analyses dealing with the main phyloge- excellent material to diagnose the evolutionary history of netic relationships of placental mammals recorded affini- the South American biota. The north of South America has ties of notoungulates and Afrotheria (O’Leary et al. 2013). provided a less fecund fossil record and has demonstrated a Toxodontids are medium to large Notoungulata of the different taxonomic composition to the southern part of the Suborder Toxodontia, characterized by a specialized ante- continent (e.g., the Paleogene from Santa Rosa, Peru; the rior dentition, with hypselodont incisor tusks and hypsodont Oligocene from Salla, Bolivia; the Miocene from La Venta, molars. Toxodontids diversified during the Cenozoic and Colombia, and Urumaco, Venezuela; Kay et al. 1997; presented the richest diversity in the Miocene (Cifelli 1985; Campbell 2004;Sa´nchez Villagra et al. 2010; Shockey and Marshall and Cifelli 1990; Nassif et al. 2000). During the Anaya 2008). Mendoza Province in central-western Early and Middle Miocene, toxodontids were represented Argentina lies to the north of the windswept plains of by Nesodon imbricatus, N. conspurcatus, N. cornutus Patagonia, and is in a suitable geographical location to (Santacrucian SALMA in Argentina and Chile); Adinothe- provide data linking both biogeographic scenarios of the rium ovinum and A. robustum (Santacrucian SALMA in South American vertebrate evolution. Argentina); Proadinotherium muensteri (Colhuehuapian SALMA in Argentina); Palyeidodon obtusum (Friasian s.s. combination of laser ablation inductively coupled plasma and Colloncuran SALMAs in Argentina, Bolivia, and mass spectrometry (LA-ICPMS) and chemical abrasion Chile), Hyperoxotodon speciosus (Santacrucian–Colloncu- isotope dilution thermal ionization mass spectrometry (CA- ran SALMAs in Argentina and Chile), and Pericotoxodon ID-TIMS). Tuff level 2 (Fig. 1b) was chosen as the most platignathus (Laventan SALMA in Colombia) (e.g., Pasc- appropriate sample for dating based on its mineralogical ual 1954; Marshall et al. 1983; Madden
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    Palaeontologia Electronica palaeo-electronica.org An exceptionally well-preserved skeleton of Thomashuxleya externa (Mammalia, Notoungulata), from the Eocene of Patagonia, Argentina Juan D. Carrillo and Robert J. Asher ABSTRACT We describe one of the oldest notoungulate skeletons with associated cranioden- tal and postcranial elements: Thomashuxleya externa (Isotemnidae) from Cañadón Vaca in Patagonia, Argentina (Vacan subage of the Casamayoran SALMA, middle Eocene). We provide body mass estimates given by different elements of the skeleton, describe the bone histology, and study its phylogenetic position. We note differences in the scapulae, humerii, ulnae, and radii of the new specimen in comparison with other specimens previously referred to this taxon. We estimate a body mass of 84 ± 24.2 kg, showing that notoungulates had acquired a large body mass by the middle Eocene. Bone histology shows that the new specimen was skeletally mature. The new material supports the placement of Thomashuxleya as an early, divergent member of Toxodon- tia. Among placentals, our phylogenetic analysis of a combined DNA, collagen, and morphology matrix favor only a limited number of possible phylogenetic relationships, but cannot yet arbitrate between potential affinities with Afrotheria or Laurasiatheria. With no constraint, maximum parsimony supports Thomashuxleya and Carodnia with Afrotheria. With Notoungulata and Litopterna constrained as monophyletic (including Macrauchenia and Toxodon known for collagens), these clades are reconstructed on the stem
  • The Largest Fossil Rodent Andre´S Rinderknecht1 and R

    The Largest Fossil Rodent Andre´S Rinderknecht1 and R

    Proc. R. Soc. B doi:10.1098/rspb.2007.1645 Published online The largest fossil rodent Andre´s Rinderknecht1 and R. Ernesto Blanco2,* 1Museo Nacional de Historia Natural y Antropologı´a, Montevideo 11300, Uruguay 2Facultad de Ingenierı´a, Instituto de Fı´sica, Julio Herrera y Reissig 565, Montevideo 11300, Uruguay The discovery of an exceptionally well-preserved skull permits the description of the new South American fossil species of the rodent, Josephoartigasia monesi sp. nov. (family: Dinomyidae; Rodentia: Hystricognathi: Caviomorpha). This species with estimated body mass of nearly 1000 kg is the largest yet recorded. The skull sheds new light on the anatomy of the extinct giant rodents of the Dinomyidae, which are known mostly from isolated teeth and incomplete mandible remains. The fossil derives from San Jose´ Formation, Uruguay, usually assigned to the Pliocene–Pleistocene (4–2 Myr ago), and the proposed palaeoenviron- ment where this rodent lived was characterized as an estuarine or deltaic system with forest communities. Keywords: giant rodents; Dinomyidae; megamammals 1. INTRODUCTION 3. HOLOTYPE The order Rodentia is the most abundant group of living MNHN 921 (figures 1 and 2; Museo Nacional de Historia mammals with nearly 40% of the total number of Natural y Antropologı´a, Montevideo, Uruguay): almost mammalian species recorded (McKenna & Bell 1997; complete skull without left zygomatic arch, right incisor, Wilson & Reeder 2005). In general, rodents have left M2 and right P4-M1. body masses smaller than 1 kg with few exceptions. The largest living rodent, the carpincho or capybara 4. AGE AND LOCALITY (Hydrochoerus hydrochaeris), which lives in the Neotro- Uruguay, Departament of San Jose´, coast of Rı´odeLa pical region of South America, has a body mass of Plata, ‘Kiyu´’ beach (348440 S–568500 W).
  • New Insights Into the Anatomy of Extinct Paucituberculatan Marsupials

    New Insights Into the Anatomy of Extinct Paucituberculatan Marsupials

    Swiss J Palaeontol DOI 10.1007/s13358-014-0063-9 An exceptionally well-preserved skeleton of Palaeothentes from the Early Miocene of Patagonia, Argentina: new insights into the anatomy of extinct paucituberculatan marsupials Analia M. Forasiepi • Marcelo R. Sa´nchez-Villagra • Thomas Schmelzle • Sandrine Ladeve`ze • Richard F. Kay Received: 8 September 2013 / Accepted: 13 February 2014 Ó Akademie der Naturwissenschaften Schweiz (SCNAT) 2014 Abstract During the Cenozoic paucituberculatans were an anterior semicircular canal (SC) projecting slightly much more diverse taxonomically and ecomorphologically dorsally from the dorsal-most point of the posterior SC, and than the three extant genera of shrew-like marsupials. lateral and posterior SCs projecting laterally to the same Among paucituberculatans, palaeothentids were abundant level. On the basis of postcranial anatomy, previous studies during the Early Miocene, although most of the fossil have demonstrated that P. lemoinei was an agile cursorial remains consist of isolated teeth or fragmentary jaws. We form, an inference supported by study of the new post- describe a new and exceptional partial skeleton of Palaeo- cranial elements. thentes lemoinei (Palaeothentidae), collected from the Santa Cruz Formation (Santacrucian age, Early Miocene) Keywords Marsupialia Á Metatheria Á Cenozoic Á in Patagonia. Whereas the skull of P. lemoinei has more South America Á Skull Á Inner ear Á Postcranium plesiomorphic traits in the face, palate, and cranial vault than that of living paucituberculatans, the dental mor- Abbreviations phology is more derived. The osseous inner ear was examined using micro-CT scanning, revealing a cochlea Institutional abbreviations with 1.9 turns, the presence of a ‘‘second crus commune’’, FMNH Field Museum of Natural History, Chicago, USA IEEUACH Universidad Austral de Chile, A.