New Early Eocene mammalian fauna from western Patagonia, Argentina

Two new fossil mammal localities from the Paleogene of central-western Patagonia are preliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of Paleocene-Eocene age. This complex includes a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks deposited after the K-T boundary. Geochronological data taken from nearby volcanic deposits that underlie and overlie the mammal-bearing levels indicate that both faunas are of late early Eocene age (Ypresian-Lutetian boundary). In addition to more than 50 species of mammals, including marsupials, ungulates, and xenarthrans, two lower molars are the oldest evidence of bats in South America. Paleobotanical and palynological evidence from inferred contemporary localities nearby indicate subtropical environments characterized by warm and probably moderately humid climate. Remarkably, this new fauna is tentatively correlated with Eocene mammals from the La Meseta Formation in the Antarctic Peninsula. We conclude that the two localities mentioned above are part of a possible new biochronological unit, but the formal proposal of a new SALMA awaits completion of taxonomic analysis of the materials reported upon here. If the La Meseta fauna is correlated biochronologically to western Patagonia, this also suggests a continental extension of the biogeographic Weddelian Province as far north as central-western Patagonia

Phylogenetic placement of Adalatherium hui (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar : implications for allotherian relationships

The phylogenetic position of Gondwanatheria within Mammaliaformes has historically been controversial. The well-preserved skeleton of Adalatherium hui from the Late Cretaceous of Madagascar offers a unique opportunity to address this issue, based on morphological data from the whole skeleton. Gondwanatheria were, until recently, known only from fragmentary dental and mandibular material, as well as a single cranium. The holotype of A. hui provides the first postcranial skeleton for gondwanatherians and substantially increases the amount of character data available to score. We sampled 530 characters and 84 cynodonts (including 34 taxa historically affiliated with Allotheria) to test the phylogenetic relationships of Gondwanatheria and Allotheria using parsimony, undated Bayesian, and tip-dated Bayesian methods. We tested three lower dental formulae for Adalatherium, because its postcanines are distinctly different from those of other mammaliaforms and cannot readily be homologized with any known dental pattern. In all analyses, Adalatherium is recovered within Gondwanatheria, most frequently outside of Sudamericidae or Ferugliotheriidae, which is congruent with establishment of the family Adalatheriidae. The different dental coding schemes do not greatly impact the position of Adalatherium, although there are differences in character optimization. In all analyses, Gondwanatheria are placed within Allotheria, either as sister to Multituberculata, nested within Multituberculata, or as sister to Cifelliodon (and Euharamiyida), or in a polytomy with other allotherians. The composition of Allotheria varies in our analyses. The haramiyidans Haramiyavia and Thomasia are placed outside of Allotheria in the parsimony and tip-dated Bayesian analyses, but in a polytomy with other allotherians in the undated Bayesian analyses

Nuevos Xenarthra del Friasense (Mioceno medio) de Argentina

[ES] Los Xenarthra argentinos de Edad Friasense (Mioceno medio) eran deficientemente conocidos hasta las minuciosas recolecciones de 1990-1993 (convenio Duke University, USA-Museo de La Plata, UNLP). A base de estos nuevos restos se reconocen cuatro géneros y siete especies nuevos de Dasypodidae (Eutatini), Glyptodontidae (Sclerocalyptini y Palaehoplophorini), Megatheriidae (Nothrotheriinae y Prepotheriinae), Mylodontidae (Scelidotheriinae) y Myrmecophagidae (Myrmecophaginae). Estos taxones permiten caracterizar este lapso y diferenciarlo tanto respecto de la Edad Santacrucense (Mioceno temprano) como de la Chasiquense (Mioceno tardío más temprano). Los Dasypodidae de la Fm. Cerro Boleadoras (Santa Cruz) indicarían una antigüedad algo menor que la del Santacrucense de la costa atlántica patagónica. En la Fm. Collón Cura ("Colloncurense") se registran los primeros indudables Megatheriinae y Mylodontinae. En la Fm. El Pedregoso ("Mayoense") aparecen xenartros más avanzados aún. En conclusión, durante el Friasense se verifican importantes cambios composicionales entre los Xenarthra, tal vez en relación con diferentes capacidades de adaptación a las variaciones climático-ambientales: entre los Tardigrada, los tipos "araucopampeanos" aparecen en el "Colloncurense"; en cambio, entre los Cingulata, se mantienen muchos tipos "pansantacrucianos" hasta el "Mayoense", y el recambio mayor se produce a lo largo del Chasiquense.[EN] The Argentine Xenarthrans from the Friasian Age (Middle Miocene) were poorly known until the detailed collections made during 1990-1993 (Duke University, USA-Museo de La Plata, UNLP Agreement). Four new genera and seven new species of Dasypodidae (Eutatini), Glyptodontidae (Sclerocalyptini and Palaehoplophorini), Megatheriidae (Nothrotheriinae and Prepotheriinae), Mylodontidae (Scelidotheriinae) and Myrmecophagidae (Myrmecophaginae), were described. Through these taxa, this lapse may be characterized and differentiated from the Santacrucian Age (Lower Miocene) as well as from the Chasicoan Age (earliest Late Miocene). The Dasypodidae from the Cerro Boleadoras Formation (Santa Cruz) indicate an age somewhat younger than that of the Santacrucian from the Patagonian Atlantic coast. In the Collón Cura Formation ("Colloncuran"), the first undoubted Megatheriinae and Mylodontinae, were recorded. In the El Pedregoso Formation ("Mayoan") appeared even more advanced xenarthrans. Finally, significant changes in the composition of the Xenarthra were verified during the Friasian, probably related to different adaptive capability to environmental and climatic changes. Among the Tardigrada, "araucanian-pampean" types appeared in the "Colloncuran"; instead, among the Cingulata, several "pansantacrucian" types lasted until the "Mayoan", and the greatest re-change occurred during the Chasicoan

Primer registro fehaciente de <em>Nopachtus coagmentatus</em> (Xenarthra, Cingulata, Glyptodontidae) en la región Pampeana, Argentina. Contexto estratigráfico

The species <em>Nopachtus coagmentatus</em> was recognized by Amegino in 1888, on the basis of sections of the caudal tube and the dorsal carapace. These remains comes from Valles de las Sierras de Córdoba near Villa Cura Brochero, and stratigraphically from the Brochero Formation (Montehermosan-Chapadmalalan [early Pliocene - late Pliocene]). Ameghino also mentioned <em>N. coagmentatus</em> for the Monte Hermoso Formation (Montehermosan), but the determination Ameghino is highly questionable. The exploitation of Precambrian rocks from the center of the Sierras Bayas in Olavarría (Buenos Aires province) allowed the identification from the bottom to the top, of La Alcancía Formation (Miocene), El Polvorín Formation (Pliocene), La Esperanza Formation and El Búho Formation (both late Pleistocene). In this contribution present osteoderms of the latero-dorsal portion of the posterior region of the dorsal carapace of <em>N. coagmentatus</em>. The specimen was extracted from brownish sandy-silt sediments of La Alcancía Quarry (36°58′40′′.06 S; 60°12′23′′.92 W) corresponding to El Polvorín Formation (Upper Chapadmalalan) and correspond to the first reliable record of <em>N. coagmentatus</em> for the Pampean region. Finally, we offer a detailed description of the specimen, and its geographic and stratigraphic provenance.<br><br>La especie <em>Nopachtus coagmentatus</em> fue reconocida por Ameghino en 1888, basándose en porciones del tubo caudal y la coraza dorsal; estos restos proceden de los Valles de las Sierras de Córdoba, en las cercanías de Villa Cura Brochero; y, estratigráficamente, de la Formación Brochero (Montehermosense - Chapadmalalense [Plioceno temprano - Plioceno tardío]). Ameghino también la menciona para la Formación Monte Hermoso (Montehermosense), pero la determinación es altamente dudosa. La explotación de rocas precámbricas en el núcleo central de las Sierras Bayas de Olavarría (provincia Buenos Aires) posibilitó el reconocimiento de la Formación El Polvorín (Plioceno) y, suprayacentes a esta, otras dos: Formación Esperanza y Formación El Búho (Pleistoceno tardío). El material que se da a conocer en esta comunicación fue exhumado en la Cantera Alcancía (36°58′40′′.06 S; 60°12′23′′.92 O), en niveles correspondientes al Chapadmalalense Superior de la Formación El Polvorín. El material mencionado consiste en osteodermos de la región dorso-lateral de la porción posterior de la coraza dorsal de <em>N. coagmentatus</em>. Se da a conocer el primer registro fehaciente de <em>N. coagmentatus</em> para la región Pampeana, se describe el material hallado, se detalla su procedencia y se presenta el perfil estratigráfico detallado correspondiente

El registro más antiguo de <i>Panochthus</i> (Xenarthra, Glyptodontidae)

<i>Panochthus</i> is one of the largest sized and most frequently recorded genera of Pleistocene South American Glyptodontidae. A recent taxonomic revision shows that the genus includes six species: <i>P. intermedius>/i> and <i>P. subintermedius</i> (early Pleistocene-middle Pleistocene), <i>P. tuberculatus</i> and <i>P. frenzelianus</i> (middle Pleistocene-late Pleistocene), whereas <i>P. greslebini</i> and <i>P. jaguaribensis</i> only can be referred to the Pleistocene sensu lato. In this contribution the oldest record of the genus <i>Panochthus</i> (MMP 5171) is presented and described. The remains came from the late Pliocene (Playa Los lobos Aloformation, Chapadmalal Formation; Chapadmalalan; <i>Paraglyptodon chapalmalensis</i> Biozone) of the Mar del Plata, Buenos Aires province, Argentina. The material is represented by a considerable fragment of dorsal carapace and some associated osteoderms, which are assignable to an indeterminate species of <i>Panochthus</i>. One of the most significant characters in the exposed surface of the osteoderms is the presence of a clear “reticular” pattern, a character only observed in <i>Panochthus</i>. From a biostratigraphic viewpoint, it is remarkable the absence of records of <i>Panochthus</i> in the Marplatan Age/Stage (late Pliocene-early Pleistocene).<br><br><i>Panochthus</i> es uno de los géneros de gliptodóntidos de mayores dimensiones y más ampliamente registrado en el Pleistoceno del sur de América del Sur. Una reciente revisión demostró que alberga seis especies distribuidas cronológicamente de la siguiente manera: <i>P. Intermedius</i> y <i>P. Subintermedius</i> (Pleistoceno temprano-Pleistoceno medio, Ensenadense); <i>P. Tuberculatus</i> y <i>P. Frenzelianus</i> tienen sus biocrones limitados al Pleistoceno medio-Pleistoceno tardío (Bonaerense-Lujanense), mientras que <i>P. Greslebini</i> y <i>P. Jaguaribensis</i> solo pueden referirse al Pleistoceno <i>sensu lato</i>. En la presente contribución se da a conocer el registro más antiguo de <i>Panochthus</i>, representado por el material MMP 5171, procedente del Plioceno tardío (Aloformación Playa Los Lobos, Formación Chapadmalal; Chapadmalalense; Biozona de <i>Paraglyptodon chapalmalensis</i>) de la localidad de Mar del Plata, Buenos Aires, Argentina. El material consiste en un gran fragmento de coraza dorsal y en varios trozos de osteodermos asociados, asignables a una especie indeterminada de <i>Panochthus</i>. Uno de los caracteres más significativos es la presencia, a nivel de la superficie expuesta de los osteodermos, de figuritas que siguen un evidente patrón reticular, solo observable en <i>Panochthus</i>. Desde el punto de vista bioestratigráfico, es llamativa la ausencia de registros de <i>Panochthus</i> en la Edad Marplatense (Plioceno tardío-Pleistoceno temprano)

The phylogenetic and biostratigraphic significance of new armadillos (Mammalia, Xenarthra, Dasypodidae, Euphractinae) from the Tinguirirican (Early Oligocene) of Chile

Two new species of early Oligocene dasypodids are described from the Tinguiririca Fauna of Chile, the basis of the recently formalised Tinguirirican South American Land Mammal ‘Age’. Specimens recovered to date, all referable to the Euphractinae, include articulated portions of the movable bands and pelvic shield, an unassociated partial mandible and skull, and isolated osteoderms. Ornamentation of the osteoderms (i.e. the shape of the central figure and keel and the arrangement of the peripheral figures) indicates that these taxa represent early diverging members of the subfamily. Cranial remains from Chile somewhat resemble Sadypus Ameghino (?early Oligocene), particularly in their long, low rostra. One of the new species from Tinguiririca also occurs in Eo‐Oligocene faunas from Patagonia (Argentina) currently under study, providing a basis for long distance biochronological correlation. The material from Tinguiririca assumes special importance given that most Eocene and Oligocene dasypodids are known exclusively from isolated osteoderms. The unusally complete material from Tinguiririca thus provides important phylogenetic insights by clarifying the morphology of the cingulate exoskeleton during a key interval in the clade's diversification