Análisis diagenético de tetrápodos del Triásico Superior, Grupo Puesto Viejo, Argentina

The Puesto Viejo Group crops out in the San Rafael Block, southwest Mendoza, Argentina. This group is an important unit for the knowledge theTriassic faunas. It is composed of basal Quebrada de los Fósiles Formation (QF) overlying by the Río Seco de la Quebrada Formation (RSQ). In this study, we report tetrapod remains from the RSQ Formation that includes, until now, exclusively therapsids. Non-mammalian therapsids predominated in terrestrial ecosystems during the Late Paleozoic and Early Mesozoic. Although cynodonts and dicynodonts have been studied from several perspectives, the relation between taxa and sedimentary context has been scarcely documented. This study is aimed to elucidate the diagenesis of tetrapods from the Puesto Viejo Group and its relation to depositional environment. Diagenetic features of therapsid bones from the RSQ Formation were analyzed through thin sections to interpret the degree of taphonomic alteration. Diagenetic processes inferred include substitution; fracturing; brittle deformation and different permineralization events. Combined analyses through scanning electron microscopy; energy-dispersive X-ray spectrometry (SEM-EDX); X-ray diffractometry (XRD) and petrographic studies reveals the substitution of hydroxyapatite by francolite. The presence of fluorine in some samples suggests a link between the elemental composition and depositional environments: floodplain and crevasse splay. Permineralization stages include infilling of vascular canals, trabeculae and fractures with iron oxides and iron carbonate minerals during the burial history. This contribution represents a relevant approach to elucidate the relation between diagenesis on tetrapods and their paleoenvironments, as exemplified in this case study from the Puesto Viejo Group during the Upper Triassic.El Grupo Puesto Viejo aflora en el Bloque San Rafael, en el suroeste de Mendoza, Argentina. Este grupo constituye una importante unidad para el conocimiento de las faunas del Triásico y está compuesto en su base, por la Formación Quebrada de los Fósiles (QF), superpuesta por la Formación Río Seco de la Quebrada (RSQ). En este estudio, se reportan restos de tetrápodos de la Formación RSQ que incluye, hasta ahora, exclusivamente terápsidos. Los terápsidos no-mamiferoides predominaron en los ecosistemas terrestres durante el Paleozoico tardío y el Mesozoico temprano. A pesar de que cinodontes y dicinodontes han sido estudiados desde varias perspectivas, la relación entre los taxones y su contexto sedimentario está escasamente documentado. Este estudio tiene como objetivo dilucidar la diagénesis de los tetrápodos del grupo Puesto Viejo y su relación con el ambiente depositacional. Las características diagenéticas de los huesos de terápsidos de la Formación RSQ se analizaron a través de secciones delgadas para interpretar el grado de alteración tafonómica. Los procesos diagenéticos inferidos incluyen la sustitución, fracturación, deformación frágil y diferentes eventos de permineralización. El análisis combinado a través de microscopía electrónica de barrido, espectrometría de rayos X de energía dispersiva (SEM-EDX), difractometría de rayos X (DRX) y estudios petrográficos revelaron la sustitución de la hidroxiapatita por francolita. La presencia de flúor en algunas muestras sugiere la vinculación entre la composición elemental y los ambientes depositacionales: llanura de inundación y lóbulo de desbordamiento. Las etapas de permineralización incluyen el relleno de canales vasculares, trabéculas y fracturas con óxidos de hierro y carbonatos de hierro durante la historia de enterramiento. Esta contribución representa un enfoque relevante para dilucidar la relación entre la diagénesis de tetrápodos y sus paleoambientes, como lo demuestra este estudio de caso del Grupo Puesto Viejo durante el Triásico Superior.Fil: Previtera, Maria Elena. 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: 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: de la Fuente, Marcelo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; ArgentinaFil: Sánchez, Eloy S.. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Laboratorio de Microscopia Electrónica y Microanálisis; Argentin

Anatomy of condorchelys antiqua sterli, 2008, and the origin of the modern jaw closure mechanism in turtles

Here we present a detailed anatomical description of cranial and post-cranial remains of a Jurassic turtle, Condorchelys antiqua Sterli, 2008, from the Caadn Asfalto Formation (Middle Jurassic) in central Patagonia. Although C. antiqua is similar in morphology to the Early Jurassic turtles Kayentachelys aprix and Indochelys spatulata, it differs in that it lacks both pterygoid teeth and a V-shaped suprapygal 2, respectively. In light of new discoveries and reinterpretations of other fossil taxa, we suggest that several changes in the evolution of the skull morphology of turtles (such as the closure of the basipterygoid articulation, the closure of the interpterygoid vacuity, the development of the secondary lateral wall in the braincase, the development of temporal emargination and/or the posterior extension of the crista supraoccipitalis) could be related to the acquisition of a stronger skull to accommodate the modern pulley system. The optimization of these characters in a phylogenetic framework shows that they are coincident with the appearance of trochlear systems (oticum or pterygoidei) in turtles, suggesting a functionally correlated relationship among them.Fil: Sterli, Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Municipal de Historia Natural San Rafael - Unidad Asociada al CCT Mendoza; Argentina. Museo Paleontológico Egidio Feruglio; ArgentinaFil: de la Fuente, Marcelo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Municipal de Historia Natural San Rafael - Unidad Asociada al CCT Mendoza; Argentin

Sliding wear of a-C:H coatings against alumina in corrosive media

This paper reports the results obtained from the study of friction and sliding wear in two corrosive solutions of an a-C:H coating deposited on 316L stainless against an alumina ball, employed as static counter part. Calculations of the values of the von Mises stresses developed at the coating–substrate interface, as soon as the ball touches the coated sample, and how this state of stress influences the response of the coated system under the corrosion environment, are presented and discussed. The results obtained from these calculations, as well as from the experiments conducted in the present research, are compared with other experiments published in the literature, where a-C:H coatings deposited on different substrates and with different coating architectures were tested in similar corrosive media. It has been determined that in those systems, where the von Mises stress in the coating, found in the vicinity of the interface, exceeds the threshold value of approximately 370MPa, coating failure with spallation will take place, regardless of the substrate nature on which this coating has been deposited. From this analysis it has been concluded that the coating yield strength is of utmost importance in conferring the a-C:H coated system there quired stability in a corrosive solution

Testudinoidea Fitzinger (Testudines: cryptodira) of the Toropí/Yupoí Formation (ca. 58-28 ka) in the province of Corrientes, Argentina: taxonomy and paleoenvironmental

Os testudinoideos recuperados da Formação Toropí/Yupoí (ca. 58-28 ka) estão representados por testudinídeos e emidídeos. Estes foram coletados em duas localidades (Província de Corrientes, Argentina): Arroyo Toropí e Santa Lucía. Da primeira localidade procedem dois testudinídeos: o holótipo de Chelonoidis lutzae, composto por partes da carapaça dorsal, plastrão e restos do esqueleto apendicular, e outro exemplar tentativamente assignado a esta espécie que está representado por fragmentos de carapaça dorsal e plastrão. Novos exemplares constituídos por restos fragmentários de testudinídeos (cf. Chelonoidis) e emidídeos (Trachemys cf. dorbigni) procedem de Santa Lucía. A partir da constatação de mapas de distribuição global de espécies atuais de testudinídeos gigantes (e.g. Chelonoidis nigra, Geochelone sulcata, Dipsochelys elephantina y Cylindraspis peltastes) e o mapa climatológico de Kottek e colaboradores se observa una congruência entre a distribuição geográfi ca destas espécies gigantes atuais com as zonas tropical e subtropical caracterizadas por climas quentes, indicando um alto grau de sensibilidade térmica para estas tartarugas terrestres. Esta informação, somada aos dados geológicos e paleontológicos da Formação Toropí/Yupoí, sugere que os Chelonoidis gigantes habitaram na área do Arroyo Toropí e Santa Lucía sob condições climáticas quentes. Por sua vez, condições quentes e úmidas são inferidas a partir da presença de Trachemys cf. T. dorbigni na mesma unidade afl orante em Santa Lucía.Remains of testudinoids from Toropí/Yupoí Formation (ca. 58-28 ka), including testudinids and emydids, were recovered from Arroyo Toropí and Santa Lucía localities (Corrientes Province, northeastern Argentina). From Arroyo Toropí two specimens of testudinid are known: the holotype of Chelonoidis lutzae (carapace, plastron and remains of the appendicular skeleton) and a partial carapace tentatively referred to this species. New specimens including remains of testudinids (cf. Chelonoidis) and emydids (Trachemys cf. T. dorbigni) have been also recovered from Santa Lucía. Comparing the global distribution of extant species of giant testudinids (e.g. Chelonoidis nigra, Geochelone sulcata, Dipsochelys elephantina and Cylindraspis peltastes) with the climate map of Kottek and collaborators, show congruence with the Tropical and Subtropical zones, characterized by warm climate. This suggests a high degree of thermosensitivity for these extant giant tortoises. This, together with the geological and paleontological data from Toropí/Yupoí Formation, allows suggesting that the giant Chelonoidis inhabited environments with warm climate conditions. In addition, warm and wet conditions are inferred in Santa Lucía from the record of Trachemys cf. dorbigni.Fil: Zacarias, Gerardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: de la Fuente, Marcelo Saul. Museo Municipal de Historia Natural San Rafael - Unidad Asociada al CCT Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zurita, Alfredo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentin

The new outfit of Neusticemys neuquina: Holw recent findings and techniques helped clarify its phylogenetic affinities

Neusticemys neuquina is one of the two known turtles from the Upper Jurassic of the Vaca Muerta Formation. Since its initial description in 1988 its taxonomic affinities have been unstable because all known specimens are postcranial elements, which seem to lack phylogenetic relevance. Initially referred, putatively, to the genus Eurysternum, it has also been considered a protostegid or a basal cryptodire. Recently, the discovery and descriptions of three skulls (MOZ 064, MACN-PV 105, MHNSR-PV-1195) and their study using computed tomography helped establish it as a member of Thalassochelydia. The new skulls have in common with Thalassochelydia: the articular process of the quadrate posteriorly oriented; the presence of a prominent, ventrally infolding ridge of the posterior surface of the processus articularis of the quadrate; a long interpterygoid contact; the presence of a pterygoid contact with the articular surfaces of the quadrate; an anterolateral recess of the anterior surface of the quadrate lateral to the processus trochlearis oticum; the presence of a fossa on the supraoccipital-opisthotic-exoccipital contact area; the foramina anterius caroticus cerebralis close together but as independent foramina in the basisphenoid; and the presence of a splenial bone in the mandible. Some of the features that distinguish it from other Thalassochelydia are the presence of a depression on the ventral surface of the basisphenoid, a relatively larger foramen nervi trigemini and reduced and steepened triturating surfaces in both the mandible and maxilla. The mandibular morphology resembles that of Dermochelys coriacea rather than that of other thalassochelydians and panchelonioids, which might indicate similarities in the feeding preferences between these species. New research has shown that thalassochelydians might have been better adapted to marine environments than previously thought and Neusticemys neuquina is not the exception.Fil: González Ruiz, Pablo. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; ArgentinaFil: de la Fuente, Marcelo Saul. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; ArgentinaFil: Fernández, Marta S.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaTurtle Evolution Symposium 2021TrelewArgentinaMuseo Paleontológico Egidio Ferugli

New remains of Prochelidella in the Anacleto Formation (Campanian levels) of Neuquén basin, Patagonia, Argentina

The new turtle remains presented here were recovered from the Anacleto Formation (Campanian) exposed in the Aguada Grande site. This area is located 10 km south of Rincón de Los Sauces city, inthe north of the province of Neuquén, Patagonia, Argentina. The specimen (MAU-Pv-AG-452)consists of a partially preserved skull, carapace remains, an almost complete plastron, and a leftilium. The new specimen is assigned to Pleurodira because its ilium is sutured to the carapace. Both Parietals, the posterior part of frontals and post orbitals, the dorsal region of the supraoccipital, both pterygoids, the basisphenoid, and part of the prootics are recognized in the skull. The carapace remains are represented by a left first costal bone in articulation with a peripheral bone, a left paired costal bone, and another fragmented coastal. The plastron is represented by both epiplastra, theen plastron, left hyoplastron, both hypoplastra, and the left xiphiplastron. The skull shows somecharacters that allow its referral to Prochelidella spp. (e.g., a developed retropterygoid foramen, and a big muscle attachment area over the basisphenoid). The visceral view of the first costal bone exhibitslong auxiliary buttresses that extend 2/3 of the costal width. This condition is also observed in the costal bone of Prochelidella buitreraensis from the Candeleros Formation (Cenomanian). The scutepattern observed in the anterior lobe of the plastron shows a large gular that extends along theentoplastral length and small extragulars over the epiplastra. In contrast, on the scheme observed inProchelidella cerrobarcinae and Prochelidella portezuelae, the gular does not extend beyond the first third of the entoplastron. The material recovered from the Anacleto Formation represents the most complete specimen outside the Prochelidella peak of diversity range (Albian Cenomanian) and the second skull recognized in this genusFil: Maniel, Ignacio Jorge. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; ArgentinaFil: de la Fuente, Marcelo Saul. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; ArgentinaFil: Filippi, Leonardo Sebastián. No especifíca;Simposio de Evolución de TortugasTrelewArgentinaMuseo Paleontológico Egidio FeruglioAsociación Paleontológica Argentin

Museums and institutions of natural sciences in the south of the province of Mendoza and their contribution to argentine paleoherpetology

Las dos instituciones más relevantes dedicadas a la promoción de las ciencias naturales en el sur de la provincia de Mendoza son el Museo de Historia Natural de San Rafael (MHNSR) (Departamento de San Rafael) y el Museo Regional de Malargüe “Jorge Luna” (MRM)(Departamento de Malargüe). La primera institución fue fundada en el año 1955 mientras que la segunda se erigió en el año 1973 y ambas se incorporaron a la órbita municipal en los primeros años de la década del ‘70 del siglo pasado. Estos museos han tenido un diferente desarrollo y proyección en lo que respecta a su actividad científica. Esto también se reflejó en el desarrollo de la paleoherpotología en el MHNSR con la incorporación de investigadores y becarios del CONICET acontecida a partir del año 2002. En el año 2006 se originó el Centro Regional de Investigación y Desarrollo Cultural, institución que desarrolló actividades paleontológicas en Malargüe principalmente entre los años 2006 y2015. Con la reciente creación del Instituto de Evolución, Ecología Histórica y Ambiente, unidad ejecutora de doble dependencia CONICET y Universidad Tecnológica Nacional, los paleontólogos continuaron su desempeño en esta unidad sin dejar el MHNSR, donde se alojan las colecciones paleontológicas. En el MRM, las colecciones se encuentran tanto en el antiguo molino del casco de la estancia “La Orteguina”,edificación colindante, y en la sala de exposición de paleontología de dicho museo. Estas instituciones resguardan pequeñas colecciones de reptiles fósiles.The two most relevant institutions dedicated to the promotion of natural sciences in the south of the Mendoza Province are the Museum of Natural History of San Rafael (MHNSR) (Department of San Rafael) and the Regional Museum of Malargue "Jorge Luna" (MRM) (Department of Malargue). The first institution was founded in 1955 whereas the second one in 1973, and both were incorporated into the municipal management in the first years of the '70s during the last century. These museums have had different trajectories and projections regarding their scientific activity. This was also reflected in the paleoherpetological development at the MHNSR with the incorporation of researchers and fellows from CONICET since 2002. The Regional Center for Cultural Research and Development is an institution that conducted paleontological activities in southern Mendoza Province between the years 2006 and 2015. With the recent creation of the Institute of Evolution, Historical Ecology and Environment, an institute that depends both from CONICET and the National Technological University, paleontologists would continue their work in this unit without leaving the MHNSR, where paleontological collections are housed. For the MRM, fossils are housed both in the adjacent old mill at the estancia "La Orteguina", as well as in the palaeontology exhibition room of this museum. These institutions house small collections of fossil reptiles.Fil: de la Fuente, Marcelo Saul. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; Argentin