A new temnospondyl record from the Upper Triassic of Argentina

The Brachyopoidea is a group of Mesozoic temnospondyls with flat, parabolic skulls that were recently reviewed and considered to include Brachyopoidea and Chigutisauridae (Warren and Marsicano, 2000; Yates and Warren, 2000, Damiani and Kitching, 2003). Brachyopids have been recorded from several different localities both in Gondwana (excluding South America) and Laurasia (Warren and Marsicano, 2000) during the Early-Middle Triassic. After the Middle Triassic, they areabsent from the fossil record for several million years until they are recorded in the Middle-Late Jurassic of China (Dong, 1985) and Mongolia (Shishkin, 1991). In contrast, chigutisaurid temnospondyls appear to be restricted to Gondwana. They are known from the Lower Triassic, Lower Jurassic and Lower Cretaceous of Australia (Warren, 1981; Warren and Hutchinson, 1983; Warren et al., 1997), the Upper Triassic of Argentina (Bonaparte, 1975; Marsicano, 1993, 1999) and India (Sengupta, 1995), and from the Upper Triassic and Lower Jurassic of South Africa (Warren and Damiani, 1999). This paper describes a new temnospondyl specimen consisting of an incomplete left mandible, preserved from the symphysis to the level of the anterior coronoid, found in strata assigned to the Late Triassic Cacheuta Formation at the Potrerillos locality in western Argentina (Marsicano et al., 2000). The mandible is here considered to be a putative brachyopid and, therefore, it would be the first occurrence of this group in South America and the youngest for Gondwana. Abbreviations-MCNAM-PV, Museo de Ciencias Naturales y Antropológicas Juan Cornelio Moyano of Mendoza (Argentina), paleovertebrados collection; UCMP, University of California Museum of Paleontology, Berkeley (USA).Fil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin

Mandibles of mastodonsaurid temnospondyls from the Upper Permian-Lower Triassic of Uruguay

Partially preserved temnospondyl mandibles from the Late Permian–Early Triassic Buena Vista Formation of Uruguay are referred to the basal stereospondyl taxon Mastodonsauridae. These represent the earliest known members of this group for South America. In most cases, this assignment was based on the characteristic morphology of the postglenoid (= postarticular) area of the lower jaw together with the presence of a hamate process. Comparisons with basal masto−donsaurids indicate that the Uruguayan specimens are phenetically similar to Gondwanan and Laurasian Early Triassic taxa, such as Watsonisuchus, Wetlugasarus, and Parotosuchus. Nevertherless, they display some characters which have not previously been described in Mesozoic temnospondyls. The Permo−Triassic Uruguayan mastodonsaurids support a Gondwanan origin for the group, an event which probably occurred sometime during the latest Permian.Fil: Piñeiro, Graciela. Departamento de Evolución de Cuencas, Sección Bioestratigrafía y Paleo-ecología, Facultad de Ciencias,; UruguayFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Damiani, Ross. Staatliches Museum für Naturkunde Stuttgart; Alemani

Temnospondyl diversity of the Permian-Triassic Colonia Orozco Local Fauna (Buena Vista Formation) of Uruguay

Temnospondyls are the most abundant constituent of the Colonia Orozco Local Fauna of the Uruguayan Buena Vista Formation (Paraná Basin), contrasting with that observed at most latest Permian and earliest Triassic assemblages elsewhere. The components of the Colonia Orozco fauna, appear to represent early stages of the turnover evidenced in the communities of continental tetrapods at the Permo-Triassic boundary. They include plesiomorphic representatives of groups present in Early Triassic assemblages as well as relicts of Late Permian taxa. In particular, the presence of a close relative of the Russian dvinosauroid, Dvinosaurus, implies a dispersal event of this taxon to Gondwana probably during the Late Permian. Comparisons of the Colonia Orozco fauna to other Permo-Triassic communities indicate that it could be older than the Brazilian Lower Triassic Catuçaba Local Fauna of the Sanga do Cabral Formation (Paraná Basin) and probably equivalent to the latest Permian Russian Vyazniki Community. Moreover, the Colonia Orozco fauna could be close to the assemblages represented in the lowermost portion of the South African Lower Triassic Lystrosaurus Assemblage Zone and probably to the Arcadia Formation of Australia.Os Temnospondyli constituem o grupo mais abundante na Fauna Local de Colonia Orozco da Formação Buena Vista no Uruguay (bacia do Paraná), contrastando com o observado na maior parte das associações conhecidas em depósitos do final do Permiano e início do Triássico. A fauna de Colonia Orozco parece representar estágios primitivos da substituição faunística que se constata nas comunidades de tetrápodos continentais no límite Permo-Triássico. Os temnospondilos da Formação Buena Vista incluem representantes plesiomórficos de grupos presentes no início do Triássico, como também relictos de componentes típicos do Permiano superior. Entre eles se destaca a presença de um dvinosaurídeo proximamente relacionado com o gênero Dvinosaurus do Permiano superior da Rússia, o qual implicaría na existência de um evento de dispersão deste táxon até o Gondwana, provavelmente no Permiano Tardío. A comparação da Fauna de Colonia Orozco com outras asociaciones Permo-Triássicas, indica que a fauna uruguaya podería ser equivalente a Comunidad de Vyazniki do Permiano mais superior da plataforma russa, y que podería ostentar um status bastante próximo às associações presentes na porção mais basal da Zona de Lystrosaurus da África do Sul e na Formação Arcadia, na Austrália. Por outro lado, a Fauna Local de Colonia Orozco sería mais antiga que a Fauna Local de Catuçaba registrada na Formação Sanga do Cabral, bacia do Paraná (Brasil), considerada de idade Triássico inferior.Fil: Piñeiro, Graciela. Universidad de la República; UruguayFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Goso, Cesar. Universidad de la República; UruguayFil: Morosi, Elizabeth. Universidad de la República; Urugua

Huellas de tetrápodos del Triásico Medio del extremo sur de América del Sur

In South America, tetrapod footprints of Middle Triassic age were only described from the Cuyana (Cerro de las Cabras Formation) and Ischigualasto-Villa Unión (Los Rastros Formation) basins in west-central Argentina. They are scarce and remain mostly undescribed. Their significance and the putative trackmakers are identified and discussed within a phylogenetic context in the present contribution. Several groups of tetrapods are suggested to be represented, as non-mammalian therapsids, crurotarsal archosaurs and putative dinosaurs. The presence of crurotarsal archosaurs and non-mammalian therapsids in Cerro de las Cabras Formation suggests a tetrapod fauna more diverse than that documented by the known body fossil record. The ichnites described from the Los Rastros Formation are, until now, the only evidence of amniotes in the Ischigualasto-Villa Unión Basin during the deposition of these levels. They indicate the presence of putative dinosaurs, crurotarsal archosaurs and non-mammalian therapsids, which are already well represented in the rest of the sequence by skeletal remains.En América del Sur, huellas de tetrápodos del Triásico Medio sólo se conocen en niveles de las cuencas Cuyana (Formación Cerro de las Cabras) e Ischigualasto-Villa Unión (Formación Los Rastros), en el centro-oeste de Argentina. Las huellas son escasas y la mayoría de los especímenes no están descriptos. En el presente trabajo el significado de estas huellas y sus supuestos generadores son discutidos en un contexto filogenético. Así, varios grupos de tetrápodos han sido identificados como terápsidos no mamalianos, arcosaurios crurotarsales y probables dinosaurios. La presencia de arcosaurios crurotarsales y terápsidos no mamalianos en niveles de la Formación Cerro de las Cabras sugiere una fauna más diversa que lo que indica el registro de restos fósiles esqueletarios conocidos para los mismos niveles. Las icnitas de la Formación Los Rastros son hasta el momento la única evidencia de amniotas en la Cuenca de Ischigualasto-Villa Unión durante la depositación de dichos niveles. Ellas indican la existencia de probables dinosaurios, arcosaurios crurotarsales y terápsidos no mamalianos, bien representados en el resto de la sequencia por restos esqueletarios.Fil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Cátedra de Paleontología de Vertebrados; ArgentinaFil: Arcucci, Andrea Beatriz. Universidad Nacional de San Luis; ArgentinaFil: Mancuso, Adriana Cecilia. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Cátedra de Paleontología de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Caselli, Alberto Tomás. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Taphonomy and Palaeoenvironments a new early Permian Tetrapod fauna from Brazil

The Early Permian Pedra de Fogo Formation of Brazil accumulated in a large intracontinentalsag-basin (Parnaíba Basin) located in sub-tropical Gondwana around 20oS(palaeolatitude). With progressive climatic drying, palaeoenvironments changed from a large,shallow lake to expansive exposed mudflats surrounding a shrinking lacustrine wetland,culminating in isolated playas fed by ephemeral streams which finally became an aeoliandune field.Our team has collected over 500 fossils from this formation in northeastern Brazil. Theyinclude actinopterygians, dipnoans and chondrichthyans, together with two fully-articulatedcoelacanths, at least four temnospondyl taxa (the archegosaurid Prionosuchus, thetrimerorhachid Procuhy, the dvinosaur Timonya, and a rhinesuchid), small-to-mid-sizedcaptorhinid reptiles (cf. Captorhinus/Captorhinikos), and a small parareptile, as well asabundant fish-scale bearing spiral coprolites.Three gradationally superimposed sedimentary facies associations are recognized in the Pedrade Fogo Formation: offshore lacustrine, shoreline/carbonate mudflats and finally anephemeral stream/dune complex. The taphonomic style of vertebrate fossils varies withdepositional facies reflecting different modes of post mortem burial.Offshore facies comprise thick beds of massive siltstone and finely-laminatedsiltstone/mudstone couplets showing algal crenulations but no infaunal burrowing, indicativeof an anoxic lake bed. Scattered actinopterygian fish skeletons with scales are rare, but somefine sandstone turbidite/inundate interbeds contain more fully-articulated aquatic tetrapods,some with soft tissue preservation, indicative of death and burial caused by storm induceddensity underflows.The carbonate mudflats facies association contains silicified algal-laminated limestonesdisplaying stromatolite mounds, tepee and desiccation structures typical of alkaline lakeshorelines. Clusters of coprolites and fish-hash lenses comprising masses of isolated teeth andscales are suggestive of heavy predation within drying ponds and channels.The ephemeral stream/dunite facies contains most of the plant material, mainly tree trunksand in places at the top of the formation rare 3-D petrifications of leaves and fructifications.We are revealing a previously unknown diversity of early Permian (+/-280 Mya) tetrapods inGondwana. While some aspects of the fauna (e.g., caporhinids, trimerorhcachids) are similarto those known from the classic Permian redbeds of the southwestern United States, thepresence of taxa such as rhinesuchids suggest that the Gondwanan tropics were an importantcradle of later Permo-Triassic biodiversity. Dvinosaurian temnospondyls were a majorcomponent of these Gondwanan tetrapod communities that originated, and diversified in andaround tropical saline to brackish water lakes and wetlands.Fil: Smith, Roger. University of the Witwatersrand; SudáfricaFil: Cisneros, Juan. Universidade Federal do Piaui; BrasilFil: Angielczyk, Ken. Field Museum of National History; Estados UnidosFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Kammerer, Christian. North Carolina Museum of Natural Sciences; Estados UnidosFil: Frobisch, Jorg. Humboldt-Universität zu Berlin; Alemania20th Palaeontological Society of Southern Africa Biennial MeetingBloemfonteinSudáfricaThe National Museum, Bloemfontei

Deep-scaled fish (Osteichthyes: Actinopterygii) from the lower Permian (Cisuralian) lacustrine deposits of the Parnaíba Basin, NE Brazil

The richly fossiliferous deposits of the Brazilian Pedra de Fogo Formation originated in an extensive aquatic system in tropical Pangaea, and grade from marginal lacustrine into marine deposits at the depocenter in the western part of the Parnaíba Basin. In addition to the well-known tetrapod and macrofloral records from these deposits, the Pedra de Fogo Formation yields extensive fish fossils indicating a diverse and abundant ichthyofauna. Among the actinopterygians, deep-bodied morphotypes are represented by whole fish as well as disarticulated dermal scales found at various localities in the states of Maranhão and Piauí. The gross morphology, ornamentation, and histology of some of these scales is highly distinctive, indicating the presence of a novel taxon (Piratata rogersmithii gen. et sp. nov.). The external surface of a Piratata scale is covered in multiple round-to-slightly elongated tubercles. The scale lacks a ganoin cover and is made up of cellular bone and odontocomplexes of orthodentine composing the tuberculated scale surface. The scale morphology and ornamentation most closely resemble that of Cleithrolepis granulatus from the Triassic of Australia and Cleithrolepis extoni from the Triassic Stormberg Beds of South Africa, but the new taxon differs from previously described species in several diagnostic morphological features. The use of scale characters in the taxonomy of ray-finned fishes and the palaeogeographic, palaeoenvironmental, and geochronological implications of the new taxon are discussed.Fil: Richter, Martha. British Museum (Natural History); Reino UnidoFil: Cisneros, Juan C.. Universidade Federal do Piaui; BrasilFil: Kammerer, Christian. North Carolina Museum Of Natural Sciences; Estados UnidosFil: Pardo, Jason. Field Museum of National History; Estados UnidosFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Frobisch, Jorg. Staatliches Museum fur Naturkunde Stuttgart; AlemaniaFil: Angielczyk, Ken. Field Museum of National History; Estados Unido

Paleozoic Crown Lungfishes from Gondwana foreshadow the Early Triassic Recovery Fauna

Modern lungfishes are renowned for tolerance of extreme environmental variation, which is thought to contribute to their abundance during the recovery from the Permo-Triassic Mass Extinction (PTME). However, the Paleozoic origins of this clade and its biogeographic context remains unclear, with a 60 Ma ghost lineage at the base of the crown lungfish diversification spanning much of the Upper Carboniferous and the entirety of the Permian. This gap is particularly perplexing given the exceptional record of archaic lungfishes within this interval, particularly within paleoequatorial Euramerica, but also within eastern Europe. One possibility is that the assembly of the crown lungfish bauplan from known Carboniferous and Permian archaic lungfish groups occurred rapidly in the recovery from the PTME. However, an alternative explanation is that the crown lungfish bauplan evolved earlier in geographic regions outside the well-sampled Carboniferous and Permian basins of Euramerica, Russia, and South Africa. The sudden appearance of a diverse crown lungfish fauna in the earliest Triassic would then represent a biogeographic release in response to climate or diversity trends associated with the PTME. New lungfish faunas from outside these basins provide an opportunity to test these hypotheses. Here we report a diverse lungfish fauna from the Early Permian Pedra de Fogo Formation (Parnaíba Basin, northeastern Brazil) comprised of abundant lungfish toothplates and rarer associated or articulated skeletal remains. This fauna lacks archaic lungfish taxa (e.g. sagenodontids, ctenodontids, and conchopomatids) characteristic of contemporary localities in equatorial Euramerica. Instead, the Parnaíba fauna preserves a diverse assemblage of derived lungfishes, including a gnathorhizid and several crown lungfishes (ceratodontiforms). The gnathorhizid is represented by abundant toothplates and several partial skulls, and shows similarities to the North American gnathorhizid genera Persephonichthys and Gnathorhiza. The ceratodontiform, which is represented by toothplates as well as several partial skulls and skeletons, shows affinities with Triassic ptychoceratodontids and arganodontids, currently considered early members of the lepidosireniform stem group. Comparison with lungfish toothplate assemblages from the Paraná Basin of southern Brazil shows that the lungfish assemblage from the Parnaíba basin is also present in the Middle Permian of Brazil, likely representing a persistent biogeographic province in western Gondwana. We hypothesize that the lungfish crown group originated early in western Gondwana, but remained biogeographically restricted until the PTME eliminated incumbent competition in better-known biogeographical provinces.Fil: Pardo, Jason. University of Calgary; CanadáFil: Kammerer, Christian. Museum Fur Naturkunde; AlemaniaFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Angielczyk, Kenneth D.. Field Museum of National History; Estados UnidosFil: Fröbisch, Jörg. No especifíca;Fil: Smith, Roger M. H.. University of Cape Town; SudáfricaFil: Cisneros, Juan C.. Universidade Federal do Piaui; BrasilAnnual Meeting Society Vertebrate PaleontologyEstados UnidosSociety of Vertebrate Paleontolog

Earliest evidence of herd-living and age segregation amongst dinosaurs

Sauropodomorph dinosaurs dominated the herbivorous niches during the first 40 million years of dinosaur history (Late Triassic–Early Jurassic), yet palaeobiological factors that influenced their evolutionary success are not fully understood. For instance, knowledge on their behaviour is limited, although herding in sauropodomorphs has been well documented in derived sauropods from the Late Jurassic and Cretaceous. Here we report an exceptional fossil occurrence from Patagonia that includes over 100 eggs and skeletal specimens of 80 individuals of the early sauropodomorph Mussaurus patagonicus, ranging from embryos to fully-grown adults, with an Early Jurassic age as determined by high-precision U–Pb zircon geochronology. Most specimens were found in a restricted area and stratigraphic interval, with some articulated skeletons grouped in clusters of individuals of approximately the same age. Our new discoveries indicate the presence of social cohesion throughout life and age-segregation within a herd structure, in addition to colonial nesting behaviour. These findings provide the earliest evidence of complex social behaviour in Dinosauria, predating previous records by at least 40 My. The presence of sociality in different sauropodomorph lineages suggests a possible Triassic origin of this behaviour, which may have influenced their early success as large terrestrial herbivores.Fil: Pol, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Mancuso, Adriana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Smith, Roger M. H.. University of the Witwatersrand; SudáfricaFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Ramezani, Jahandar. Massachusetts Institute of Technology; Estados UnidosFil: Cerda, Ignacio Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Otero, Alejandro. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; ArgentinaFil: Fernandez, Vincent. European Synchrotron Radiation; Franci

Comparación entre dos icnocomunidades de aves del Mioceno: Formación Vinchina (provincia de La Rioja) y Formación Sijes (provincia de Salta)

El presente trabajo tiene como objetivo comparar cuantitativa y cualitativamente dosicnocomunidades del Mioceno provenientes de la Formación Vinchina (provincia de La Rioja) y la Formación Sijes (provincia de Salta). En ambas unidades, se registranpaleoambientes lacustres comparables que ofrecieron condiciones y recursos semejantes,que dieron lugar a posibles nichos ecológicos muy similares, con una amplia variedad dehuellas fósiles producidas por aves, caracterizadas dentro de la Icnofacies de shorebird.Numerosos trabajos previos han estudiado minuciosamente ambas formaciones desde elcontenido icnológico; en este, además, se incluye material inédito de las dos formaciones.Por medio de un análisis cualitativo de formas, tamaños, cantidad de improntas de dígitos,ángulos e impresiones de membrana interdigital, se agruparon los ejemplares en cincoecomorfotipos: Phoenicopteriformes, Charadriiformes acuáticas, Anatiformes,Charadriiformes terrestres y Recurvirostriformes. Estas tipologías representan unarelación ecológica, aunque no necesariamente representan taxonómicamente a losproductores. Una vez obtenida esta primera clasificación, se procedió a compararcuantitativamente por medio de Índices de Disimilitud estándar: Simpson, Sørensen,Anidamiento resultante y el de Lennon-Basado en la riqueza. Como resultado, ambasformaciones mostraron alto grado de similitud, pero con recambio espacial, donde sedestaca que la icnoasociación lacustre de la Formación Vinchina es mucho máshomogénea en sus formas que la icnoasociación lacustre de la Formación Sijes, cuyavariación de ecomorfotipos es mucho más notoria.Fil: Farina, Martin Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: de la Fuente, Juan Manuel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Vera, Rocío Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Krapovickas, Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina34 Jornadas Argentinas de Paleontología de VertebradosMendozaArgentinaInstituto Argentino de Nivología, Glaciología y Ciencias AmbientalesMuseo de Historia Natural de San RafaelMuseo de Ciencias Naturales y Antropológicas J. Cornelio Moyan

Chigutisaurid amphibians from the Upper Triassic of Argentina and their Phylogenetic relationships

A revision of the temnospondyl chigutisaurids from the Upper Triassic of Argentina is presented. The validity of the taxa originally proposed is discussed in the light of new material. The genus Pelorocephalus (Chigutisauridae) is diagnosed by the presence of a longitudinally keeled cultriform process, occurrence of the anterior Meckelian fenestra on the suture between splenial and postsplenial, location of the chordatympanic foramen on the contact between angular and prearticular, and exposure of the angular on the lingual mandibular surface. Three species, Pelorocephalus mendozensis, P. tenax and P. cacheutensis, are distinguished mainly by differences in the structure of the occiput. Phylogenetic relationships among all known representatives of this family, including taxa from India and Australia, are discussed.Fil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin