124 research outputs found

    A new species of Varanus (Anguimorpha: Varanidae) from the early Miocene of the Czech Republic, and its relationships and palaeoecology

    Get PDF
    Skeletal remains of a new early Miocene (Ottnangian, MN 4 mammal zone) monitor lizard, Varanus mokrensis sp. nov., are described from two karst fissures in the Mokr√°-Western Quarry (1/2001 Turtle Joint; 2/2003 Reptile Joint), Czech Republic, providing the first documented example of a European varanid for which osteological data permit a well-supported assignment to the genus Varanus. The new species is morphologically similar to the Recent Indo-Asiatic varanids of the Varanus bengalensis group. It differs from all other Varanus species on the basis of a single autapomorphy and a combination of 11 characters. As a distinguishing feature of V. mokrensis, the parietal and squamosal processes of the postorbitofrontal form a narrowly acute angle. The teeth show distinct, smooth cutting edges along the mesial and distal margins of the apical portion of their crowns. This feature is not observed in most extant Asiatic Varanus species and may represent a plesiomorphic condition. The results of parsimony phylogenetic analyses, with and without character reweighting, reveal poor resolution within Varanus. A Bayesian analysis shows V. mokrensis to be closely related to extant representatives of the Indo-Asiatic Varanus clade, with close affinities to the V. bengalensis species group. The topology of the Bayesian tree supports the hypothesis that Miocene monitors from Mokr√° are representatives of a lineage that is ancestral to the well-defined clade of extant African varanids, including the early Miocene V. rusingensis. In addition, our results support a Eurasian origin for the varanid clade. The extant African Varanus species probably originated in the late Oligocene. The radiation of African varanids probably occurred during the late Oligocene to early Miocene time interval. The occurrence of Varanus in the early Miocene of Mokr√°-Western Quarry corresponds to the warm phase of the Miocene Climatic Optimum. Remains of a diverse aquatic and heliophobe amphibian fauna at the 2/2003 Reptile Joint site indicate more humid conditions than those at the 1/2001 Turtle Joint site

    A basal lithostrotian titanosaur (Dinosauria: Sauropoda) with a complete skull: Implications for the evolution and paleobiology of titanosauria

    Get PDF
    We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian - Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. Sarmientosaurus exhibits the following distinctive features that we interpret as autapomorphies: (1) maximum diameter of orbit nearly 40% rostrocaudal length of cranium; (2) complex maxilla - lacrimal articulation, in which the lacrimal clasps the ascending ramus of the maxilla; (3) medial edge of caudal sector of maxillary ascending ramus bordering bony nasal aperture with low but distinct ridge; (4) ¬ītongue-like¬ī ventral process of quadratojugal that overlaps quadrate caudally; (5) separate foramina for all three branches of the trigeminal nerve; (6) absence of median venous canal connecting infundibular region to ventral part of brainstem; (7) subvertical premaxillary, procumbent maxillary, and recumbent dentary teeth; (8) cervical vertebrae with ¬īstrut-like¬ī centroprezygapophyseal laminae; (9) extremely elongate and slender ossified tendon positioned ventrolateral to cervical vertebrae and ribs. The cranial endocast of Sarmientosaurus preserves some of the most complete information obtained to date regarding the brain and sensory systems of sauropods. Phylogenetic analysis recovers the new taxon as a basal member of Lithostrotia, as the most plesiomorphic titanosaurian to be preserved with a complete skull. Sarmientosaurus provides a wealth of new cranial evidence that reaffirms the close relationship of titanosaurs to Brachiosauridae. Moreover, the presence of the relatively derived lithostrotian Tapuiasaurus in Aptian deposits indicates that the new Patagonian genus represents a ¬īghost lineage¬ī with a comparatively plesiomorphic craniodental form, the evolutionary history of which is missing for at least 13 million years of the Cretaceous. The skull anatomy of Sarmientosaurus suggests that multiple titanosaurian species with dissimilar cranial structures coexisted in the early Late Cretaceous of southern South America. Furthermore, the new taxon possesses a number of distinctive morphologies - such as the ossified cervical tendon, extremely pneumatized cervical vertebrae, and a habitually downward- facing snout - that have rarely, if ever, been documented in other titanosaurs, thus broadening our understanding of the anatomical diversity of this remarkable sauropod clade. The latter two features were convergently acquired by at least one penecontemporaneous diplodocoid, and may represent mutual specializations for consuming low-growing vegetation.Fil: Mart√≠nez, Rub√©n Dar√≠o. Universidad Nacional de la Patagonia; ArgentinaFil: Lamanna, Matthew C.. Carnegie Museum Of Natural History; Estados UnidosFil: Novas, Fernando Emilio. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Oficina de Coordinaci√≥n Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; ArgentinaFil: Ridgely, Ryan C.. Ohio University College Of Osteopathic Medicine; Estados UnidosFil: Casal, Gabriel. Universidad Nacional de la Patagonia; ArgentinaFil: Mart√≠nez, Javier E.. Hospital Regional de Comodoro Rivadavia; ArgentinaFil: Vita, Javier R.. Resonancia Magn√©tica Borelli; ArgentinaFil: Witmer, Lawrence M.. Ohio University College Of Osteopathic Medicine; Estados Unido

    New information on the braincase and inner ear of Euparkeria capensis Broom: implications for diapsid and archosaur evolution

    Get PDF
    Since its discovery, Euparkeria capensis has been a key taxon for understanding the early evolution of archosaurs. The braincase of Euparkeria was described based on a single specimen, but much uncertainty remained. For the first time, all available braincase material of Euparkeria is re-examined using micro-computed tomography scanning. Contrary to previous work, the parabasisphenoid does not form the posterior border of the fenestra ovalis in lateral view, but it does bear a dorsal projection that forms the anteroventral half of the fenestra. No bone pneumatization was found, but the lateral depression of the parabasisphenoid may have been pneumatic. We propose that the lateral depression likely corresponds to the anterior tympanic recess present in crown archosaurs. The presence of a laterosphenoid is confirmed for Euparkeria. It largely conforms to the crocodilian condition, but shows some features which make it more similar to the avemetatarsalian laterosphenoid. The cochlea of Euparkeria is elongated, forming a deep cochlear recess. In comparison with other basal archosauromorphs, the (C) 2016 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution Licens

    Braincase of panphagia protos (dinosauria, sauropodomorpha)

    Get PDF
    We describe a partial braincase of the basal sauropodomorph Panphagia protos from the Upper Triassic (midCarnian) horizons of the Ischigualasto Formation. The disarticulated braincase from a subadult individual includes one frontal, both parietals, one prootic, and the supraoccipital. The frontal is longer anteroposteriorly than it is wide transversely, has a small anterolateral process, and an elongate oval depression for the olfactory bulb. The supraoccipital is broader transversely than it is deep dorsoventrally and lacks a pronounced median nuchal eminence. Some braincase features that characterize more derived basal sauropodomorphs are not present in Panphagia, including a broader frontal and reduced anterior tympanic and floccular recesses. Panphagia appears to represent an early stage in the evolution of sauropodomorph dinosaurs.Describimos la caja craneana parcial del sauropodomorfo basal Panphagia protos proveniente de horizontes del Tri√°sico superior (Carniano medio) de la Formaci√≥n Ischigualasto. La caja craneana desarticulada es de un individuo sub-adulto e incluye un frontal, dos parietales, un pro√≥tico y el supraoccipital. El frontal es m√°s largo anteroposteriormente que ancho transversalmente, tiene un peque√Īo proceso anterolateral y una depresi√≥n alargada oval para el bulbo olfatorio. El supraoccipital es transversalmente m√°s ancho que dorsoventralmente alto y carece de una eminencia nucal media pronunciada. Algunas de las caracter√≠sticas que caracterizan los neurocr√°neos de sauropodomorfos basales m√°s derivados no est√°n presentes en Panphagia, incluyendo el frontal ancho y la reducci√≥n de las cavidades timp√°nica anterior y flocular. Panphagia parece representar una etapa temprana en la evoluci√≥n de los dinosaurios sauropodomorfos.Fil: Mart√≠nez, Ricardo N√©stor. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; ArgentinaFil: Haro, Jose Augusto. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; ArgentinaFil: Apaldetti, Graciela Cecilia. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; Argentin

    Cladistic analysis of Iguania and a fossil lizard from the late pliocene of northwestern Argentina

    No full text
    A fragmentary fossil lizard from Uquía Formation (Late Pliocene), Jujuy Province, Argentina, is described. The material consists of disarticulated cranial bones from the snout and jaw that were part of a microvertebrate fossil assemblage generated by accumulation of predatory birds pellets. The phylogenetic analysis of 396 morphological characters indicates a sister-group relationship between the new taxon and a clade formed by the families Liolaemidae, Leiocephalidae, and Tropiduridae. Its uncertain position and substantial morphological differences justify its placement in a new genus. We present a detailed osteological description of the material, and compare the morphological features with other Iguanoidea. In the context of this new analysis of Iguania, we included Pristiguana brasiliensis, the oldest know iguanian from South America. The results of this analysis support the monophyletic status of Iguanoidea and other groups within Iguania that are named and diagnosed. © 2012 Society for the Study of Amphibians and Reptiles.Fil: Daza Vaca, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; ArgentinaFil: Abdala, Virginia Sara Luz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; ArgentinaFil: Arias Becerra, Joan Salvador. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; ArgentinaFil: Garcia Lopez, Daniel Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Ortiz, Pablo Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentin

    Documenting the NICU design dilemma: comparative patient progress in open-ward and single family room units

    Get PDF
    Objective:To test the efficacy of single family room (SFR) neonatal intensive care unit (NICU) designs, questions regarding patient medical progress and relative patient safety were explored. Addressing these questions would be of value to hospital staff, administrators and designers alike. Study Design:This prospective study documented, by means of Institution Review Board-approved protocols, the progress of patients in two contrasting NICU designs. Noise levels, illumination and air quality measurements were included to define the two NICU physical environments. Result:Infants in the SFR unit had fewer apneic events, reduced nosocomial sepsis and mortality, as well as earlier transitions to enteral nutrition. More mothers sustained stage III lactation, and more infants were discharged breastfeeding in the SFR. Conclusion:This study showed the SFR to be more conducive to family-centered care, and to enhance infant medical progress and breastfeeding success over that of an open ward
    • ‚Ķ
    corecore