Estudio de la morfología de la mandíbula y la dieta en mamíferos depredadores vivientes y representantes de la Superfamilia Borhyaenoidea (Marsupialia, Sparassodonta)

Sparassodonta ha sido descripto como un grupo de predadores diverso en lo que respecta a dieta, incluyendo desde formas omnívoras a netamente carnívoras o con hábitos carroñeros-osífragos. Estudios previos se han basado en descripciones cualitativas e índices dentarios para realizar estas inferencias. En este trabajo, se estudió una muestra de 541 especímenes depredadores actuales (145 de Metatheria y 396 de Carnivora), representantes de un amplio rango de dietas (hipercarnívoros, mesocarnívoros, omnívoros, herbívoros, insectívoros) y 13 especímenes del Mioceno pertenecientes al Orden Sparassodonta. Utilizando morfometría geométrica, se analizó la variación de forma de la mandíbula y el molar "carnicero" inferior. Mediante un análisis discriminante basado en los componentes principales de forma (variables dependientes) y la dieta (variable categórica independiente), se obtuvieron las siguientes asignaciones dietarias: Arctodictis munizi (Mercerat), A. sinclairi (Marshall) y Borhyaena tuberata (Ameghino), hipercarnívoros con altas probabilidades (más de 80% por especie); Prothylacynus patagonicus (Ameghino), intermedio entre hipercarnívoro (48%) y mesocarnívoro (44%); y Cladosictis patagonica (Ameghino) y Sipalocyon gracilis (Ameghino), mesocarnívoros con altas probabilidades (más de 75%). Los clasificados como hipercarnívoros presentaron talónidos altamente reducidos, carniceros ubicados posteriormente y mandíbulas robustas; los asignados al grupo de mesocarnívoros talónidos poco reducidos y ramas horizontales más delgadas y curvas; mientras que P. patagonicus presentó una morfología intermedia, con talónido reducido y rama horizontal delgada. Los resultados son congruentes y refuerzan las inferencias obtenidas en trabajos previos; sin embargo, C. patagonica y P. patagonicus son aquí descriptos como menos hipercarnívoros que lo evidenciado exclusivamente por índices dentarios.Sesiones libresFacultad de Ciencias Naturales y Muse

First fossil record of the South American frog genus <i>Odontophrynus</i> Reinhardt and Lütken, 1862 (Anura, Neobatrachia)

<p>The frog genus <i>Odontophrynus</i> comprises 10 species arranged in three species groups that inhabit southeastern South America. In Argentina, it is represented by the <i>O. americanus</i> and <i>O. occidentalis</i> species groups and, despite being a fairly common taxon of the extant herpetofauna, it has no known fossil record. Here we report on the first fossil record of the genus, based on an almost complete right ilium from the lower levels of the Buenos Aires Formation (OIS 11, Bonaerian age, middle Pleistocene) in the Bonaerian Pampas of Argentina. The taxonomic allocation is derived from a thorough survey of anuran ilia and is grounded in a set of distinct ilial characters that, in combination, do not occur in any other anuran. These include: ilium not fused to ischium; well-developed dorsal acetabular expansion; broad preacetabular zone with a shallow preacetabular fossa; straight ilial shaft lacking dorsal ridge; and spike-like dorsal prominence bearing a distinct dorsal protuberance. Additionally, after comparing with a large sample of specimens representing most species of <i>Odontophrynus</i>, we propose two main characters (high spike-like dorsal prominence, absence of a lateral knob on the dorsal prominence) that allow referral to <i>Odontophrynus</i> aff. <i>O. americanus</i> or <i>O. cordobae</i>.</p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Turazzini, G. F., M. L. Taglioretti, and R. O. Gómez. 2016. First fossil record of the South American frog genus <i>Odontophrynus</i> Reinhardt and Lütken, <a href="#cit0031" target="_blank">1862</a> (Anura, Neobatrachia). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1228657.</p

A late Eocene frog assemblage from the Geste Formation, Puna of north-western Argentina

Frogs (Anura) are major components of tetrapod communities in the Neotropics and, according to divergence-time estimates, were already diverse in early Palaeogene times, but this is still poorly documented in the fossil record. A late Eocene frog assemblage from the Geste Formation exposed at Antofagasta de la Sierra (Catamarca province) is here described, providing a first glimpse into the Palaeogene anuran diversity in the present-day Puna of north-western Argentina. The assemblage is composed by at least four hyloid neobatrachian taxa having miniature to large body-sizes, ranging 17–81 mm estimated snout-vent length. Neither the families currently found in the Puna-Altiplano, nor those from the Cretaceous – Eocene of southern South America, are represented. The assemblage comprises possible brachycephaloids, odontophrynids, and hemiphractids, suggesting climatic and environmental conditions very different from the harsh conditions prevailing today in the Puna-Altiplano and a biogeographical link with Amazonia. The joint presence of these taxa is currently restricted to the nearby Austral Yungas and the Atlantic Forest, suggesting that the late Eocene frogs likely inhabited a humid forest. The new frog assemblage constitutes a rare window to the early evolution of Neotropical anurans and a major leap forward in the palaeoenvironmental reconstruction of the Puna during Eocene times.</p

First fossil record of the South American frog genus Odontophrynus Reinhardt and Lütken, 1862 (Anura, Neobatrachia)

The frog genus Odontophrynus comprises 10 species arranged in three species groups that inhabit southeastern South America. In Argentina, it is represented by the O. americanus and O. occidentalis species groups and, despite being a fairly common taxon of the extant herpetofauna, it has no known fossil record. Here we report on the first fossil record of the genus, based on an almost complete right ilium from the lower levels of the Buenos Aires Formation (OIS 11, Bonaerian age, middle Pleistocene) in the Bonaerian Pampas of Argentina. The taxonomic allocation is derived from a thorough survey of anuran ilia and is grounded in a set of distinct ilial characters that, in combination, do not occur in any other anuran. These include: ilium not fused to ischium; well-developed dorsal acetabular expansion; broad preacetabular zone with a shallow preacetabular fossa; straight ilial shaft lacking dorsal ridge; and spike-like dorsal prominence bearing a distinct dorsal protuberance. Additionally, after comparing with a large sample of specimens representing most species of Odontophrynus, we propose two main characters (high spike-like dorsal prominence, absence of a lateral knob on the dorsal prominence) that allow referral to Odontophrynus aff. O. americanus or O. cordobae. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Turazzini, G. F., M. L. Taglioretti, and R. O. Gómez. 2016. First fossil record of the South American frog genus Odontophrynus Reinhardt and Lütken, 1862 (Anura, Neobatrachia). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1228657.Fil: Turazzini, Guillermo Fidel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; ArgentinaFil: Taglioretti, Matias Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; ArgentinaFil: Gomez, Raul Orencio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentin