A large cockroach from the mesosaurbearing Konservat-Lagerstätte (Mangrullo Formation), Late Paleozoic of Uruguay

Barona arcuata, n.gen et n.sp., a left forewing of a relatively large cockroach of the Order Blattaria, is described from mesosaur-bearing lagoonal shales of the Mangrullo Formation (north-eastern Uruguay). While most of the insect remains recovered from the Mangrullo Formation come from sandy limestones, associated to scarce isolated mesosaur bones and pygocephalomorph crustaceans, the cockroach wing here described was found in the overlaying green to brownish, gray and dark black shales associated to intercalated bentonites and evaporitic gypsum crystals. Barona arcuata shares some features with typical Late Carboniferous taxa such as its general venation pattern and outline of the wing, four main and powerful veins arising close together from near the base of the wing, Sc simple forked, pectinate, reaching the costal border through a long fork, R and M bifurcating and terminating in the wing margin above and below the apex respectively, short and narrow CuA, and the presence of a broad interspace between CuP and AA. Cross venation seems to be absent or it was not preserved. Some characters might relate Barona arcuata to the Late CarboniferousEarly Permian Neothroblattinidae such as the presence of sigmoidal veins in the anal area, a condition not found in any of the remaining representatives of the Palaeozoic Blattaria. Intriguingly, the Uruguayan blattarian also presents a strong similarity with Qilianiblatta namurensis Zhang, Schneider & Hong, 2012 from the Westphalian of China, clearly a smaller taxon that is also difficult to relate to any of the preexistent families. The apparent plesiomorphic venation pattern of the new species which is reminiscent of that present in the oldest known blattarians, is in agreement with a Permo-Carboniferous (Gzhelian-Asselian) age for the Mangrullo Formation also supported by the presence of a macrofloral assemblage dominated by arborescent lepidondendrids and other lycopsids and the pygocephalid-like morphology of the pygocephalomorph crustaceans from the same levels

A reassessment of the taxonomic position of mesosaurs, and a surprising phylogeny of early amniotes

We reassess the phylogenetic position of mesosaurs by using a data matrix that is updated and slightly expanded from a matrix that the first author published in 1995 with his former thesis advisor. The revised matrix, which incorporates anatomical information published in the last 20 years and observations on several mesosaur specimens (mostly from Uruguay) includes 17 terminal taxa and 129 characters (four more taxa and five more characters than the original matrix from 1995). The new matrix also differs by incorporating more ordered characters (all morphoclines were ordered). Parsimony analyses in PAUP 4 using the branch and bound algorithm show that the new matrix supports a position of mesosaurs at the very base of Sauropsida, as suggested by the first author in 1995. The exclusion of mesosaurs from a less inclusive clade of sauropsids is supported by a Bremer (Decay) index of 4 and a bootstrap frequency of 66%, both of which suggest that this result is moderately robust. The most parsimonious trees include some unexpected results, such as placing the anapsid reptile Paleothyris near the base of diapsids, and all of parareptiles as the sister-group of younginiforms (the most rownward diapsids included in the analyses). Turtles are placed among parareptiles, as the sister group of pareiasaurs (and in diapsids, given that parareptiles are nested within diapsids). This unexpected result offers a potential solution to the long-lasting controversy about the position of turtles because previous studies viewed a position among diapsids and among parareptiles as mutually exclusive alternatives

Was Mesosaurus an aquatic animal? How do we know If an ancient species was aquatic or terrestrial?

Mesosaurs are lizard-like reptiles that lived at the beginning of the Permian Period (280–290 million years ago) or even earlier. Mesosaurs are known from thousands of skeletons recovered in Uruguay, Brazil, and Southern Africa, including young and adult individuals and even an embryo and a pregnant female. For years, mesosaurs have been considered aquatic (water-living) animals, because they have several characteristics of species that are adapted to an aquatic life, like webbed hands and feet and the presence of thickened and compact bones. However, mesosaurs also share several features with terrestrial (land-living) species, such as the structure of the hips, the limbs, and the heels. To figure out whether mesosaurs are actually aquatic or terrestrial, we studied vertebral columns (backbones) of Mesosaurus and compared them to those of other aquatic and terrestrial animals. Studying the variations in the length of the vertebrae can reveal how the animals moved and whether they were adapted to terrestrial or aquatic environments. Surprisingly, we found that Mesosaurus is more similar to terrestrial animals, which changes our ideas about their lifestyle

Isometry in mesosaurs: Implications for growth patterns in early amniotes

Mesosaurs were small amphibious tetrapods that lived in western Gondwana during the Early Permian or even earlier, when temperate Permo-Carboniferous conditions initiated after the glaciations that affected the southern region of Pangea. In this contribution, we applied traditional linear regression morphometrics to analyse proportions of both the skull and limb bones in more than 100 mesosaur specimens. The analyses revealed that all mesosaur bones scale remarkably close to a model of geometrical similarity (isometry), and that this pattern is particularly strong in long bones and also in the skull. These results indicate that juvenile and adult mesosaurs do not display appreciable change in bone proportions, meaning that there are few or no noticeable differences between them during growth. The well-defined isometry, and particularly, the high interrelation between metatarsals and phalanges permit us to suggest that the mesosaur hind limb is subject to notable modularity. This evidence strongly argues that the differences previously described to support three mesosaur species in Western Gondwana, might instead reflect natural intraspecific variability, taphonomic features or even possible sexual dimorphism, as recently suggested. Our study also reinforces the general plesiomorphic structure of the mesosaur skeleton, which along with some cranial specializations for ecological fitness and the evidence of strong isometric growth as we demonstrate herein, may suggest new hypotheses of relationships for mesosaurs which thus would position them as more basal amniotes than previously thought

Age constraints on the Paleozoic Yaguarí-Buena Vista succession from Uruguay: paleomagnetic and paleontologic information

The Yaguarí and the Buena Vista formations from Uruguay are historically correlated to the Brazilian Rio do Rasto and Sanga do Cabral formations, respectively, as they have some lithostratigraphic similarities, indicating a Permo-Triassic or even Triassic age of the Yaguarí-Buena Vista succession. However, they differ in the fossil indexes that characterize the faunistic communities present in both countries. A paleomagnetic work was carried out on some sections of the Buena Vista and the Yaguarí formations, as well as on some layers of bentonites, underlying the Buena Vista sediments. The alternating field and thermal demagnetization procedures revealed both normal and reversed magnetization components, but the samples showed evidence of secondary magnetic minerals and possibly remagnetizations. The calculated paleomagnetic pole for the Yaguarí-Buena Vista Formation plots near to the poles for the Choiyoi magmatism that is believed to be responsible for the bentonite accumulation, it is also in agreement with other Permian paleomagnetic poles for South America. Based on the paleomagnetic results, the available radiometric data for the bentonites, and the fossiliferous content, a Late Permian (Lopingian) age is assigned to the Yaguarí-Buena Vista rocks

Madera enigmática y primera evidencia de tetrápodos en Formación Yaguarí (Pérmico medio-superior), Uruguay

This article describes an intriguing fossil material recently found in the fine-grained sandstone levels from the upper section of the Yaguarí Formation of Uruguay. The nature of this specimen and its relationships were, initially, not easy to determine with confidence although it was subjected to several analyses, such as morphological and comparative examination complemented with preparation of thin sections and microanatomical and chemical studies under SEM. However, the anatomical structure shown in the performed transversal thin sections allowed solving the issue on the different animal or plant interpretations of the fossil specimen, which was finally discerned in favor of the latter. Therefore, after a detailed comparative study of the thin sections, we concluded that the specimen is a wood fragment related to the Dadoxylon-Araucarioxylon complex. Moreover, in order to provide a better biostratigraphic calibration for these deposits until now devoid of fossils, we include a preliminary description of recently found fossil footprints, which represent the first evidence of the presence of tetrapods in levels of the Yaguarí Formation (sensu Elizalde et al., 1970), below the conglomerates that have yielded the Colonia Orozco Fauna. The footprints were preliminary assigned to the ichnotaxa cf. Karoopes isp, cf. Capitosauroides isp., and cf. Pachypes isp., suggesting the presence of gorgonopsids and therocephalian therapsids and pareiasauromorphs, respectively. The Middle-Late Permian age recently suggested for the Yaguarí Formation based on paleomagnetic and radioisotopic studies is here supported by the described fossils, which thus constitute preliminary but nonetheless relevant discoveries for deposits whose fossiliferous potential has yet to be explored.Este artículo describe un intrigante fósil recientemente descubierto en niveles de areniscas finas a medias de la sección superior de la Formación Yaguarí de Uruguay. La naturaleza y las afinidades de este espécimen no fueron inicialmente fáciles de determinar, a pesar de ser sometido a numerosos estudios, incluido un análisis anatómico-comparativo complementado con la preparación de secciones delgadas y análisis de su microestructura bajo Microscopio Electrónico de Barrido. La microestructura mostrada por las láminas delgadas en corte transversal permitió finalmente resolver el problema sobre discernir entre una naturaleza animal o vegetal del espécimen, siendo la última la aceptada. El detallado estudio comparativo de las secciones delgadas reveló que el espécimen es un fragmento de madera relacionado al complejo Dadoxylon-Araucarioxylon. Asimismo, para proveer una mejor calibración temporal de los depósitos de la sección superior de la Formación Yaguarí (Miembro Villa Viñoles), también se incluye en este trabajo una descripción preliminar de huellas de tetrápodos recientemente halladas en esta unidad, las cuales representan la primera evidencia de la presencia de tetrápodos en niveles de la Formación Yaguarí (sensu Elizalde et al., 1970) subyacentes a los conglomerados portadores de la Fauna de Colonia Orozco. Las huellas fueron asignadas a los icnotaxa cf. Karoopes isp., cf. Capitosauroides isp. y cf. Pachypes isp., sugiriendo la presencia de terápsidos gorgonópsidos y therocefalidos y de pareiasauromorfos, respectivamente. La edad Pérmico Medio a Tardío recientemente sugerida para la Formación Yaguarí, basado en estudios de paleomagnetismo sustentados por dataciones radioisotópicas, es congruente con la aportada por los fósiles aquí descriptos, que, aunque fragmentarios, constituyen descubrimientos preliminarmente relevantes para depósitos cuyo potencial fosilífero no ha sido aún explorado.CSIC: I+D 2016_24

The Hum River (current Negro River) before and after the Rincón del Bonete dam at San Gregorio de Polanco (Tacuarembó, Uruguay)

La primera usina de generación hidroeléctrica conocida como represa "Dr. Gabriel Terra", que se instaló sobre el Río Negro (Río Hum para los indígenas) en 1945, inundó las zonas más bajas a su alrededor y modificó el paisaje natural del Paso Polanco en el Departamento de Tacuarembó. Desde entonces, el Hum se ensanchó formando un gran lago de aproximadamente 120 mil hectáreas y transformó al pueblo allí establecido en el hoy reconocido balneario turístico San Gregorio de Polanco. De esa forma, la obra transformó el paisaje natural que allí existía en un ambiente modificado por el hombre y dejó una huella ambiental and socioeconómica que no sólo sería irreversible sino que daría lugar a cambios comparativamente más severos que impactaron aún más el ecosistema del río, y produjeron una gradual contaminación de sus aguas. El embalse del Río Hum estuvo inicialmente dirigido a la producción de energía hidroeléctrica, pero es también utilizado como fuente de agua para el consumo humano, para abastecer al turismo y a sectores como la pesca y la cría artificial de peces para exportación, en general aspectos que pueden considerarse como positivos para la comunidad. No obstante, la construcción de esta obra afectó considerablemente el monte ribereño, impactó el hábitat de muchas especies de la fauna autóctona tanto acuática como terrestre y produjo el desplazamiento obligado de gran parte de la población que tenía un proyecto de vida y perspectivas de prosperidad en su pueblo natal. Evidentemente, estas consecuencias representan el impacto negativo inmediato que dejó la represa para Rincón de Bonete, pero en la percepción de la población actual parecen ser, quizás por desconocimiento, poco significativas. El gran embalse ha atraído inversiones para desarrollar proyectos que se proponen como importantes para la economía de la región y del país como la producción de pasta de celulosa. Pero las derivaciones ambientales de estas actividades para con la preservación del ecosistema, son aún inciertas. El objeto de este trabajo es mostrar un panorama general del ecosistema del Río Hum y la población que se desarrollaba a su alrededor previo a la construcción de la represa en Rincón de Bonete, de manera de disponer de esa información en torno a la evaluación de la naturaleza de los cambios, tanto ambientales como sociales que están reflejados en el paisaje actual de la zona. Asimismo, se discuten las implicancias de la nueva dinámica hidráulica del río Hum post embalse, particularmente los procesos geomorfológicos del flujo que generaron un cambio en los patrones de erosión y depositación que influyeron en la geología del lugar, dejando al descubierto yacimientos paleozoicos portadores de importantes fósiles para nuestro patrimonio cultural que son descritos por primera vez en este trabajo.The first hydroelectric power plant known as the "Dr. Gabriel Terra" dam, which was installed on the Río Negro (Río Hum for the Indians) in 1945, flooded the lowest areas around it and modified the natural landscape of Paso Polanco in the Department of Tacuarembó. Since then, the Hum widened forming a large lake of approximately 120 thousand hectares and transformed the town there established in the now recognized tourist resort San Gregorio de Polanco. In this way, the work transformed the natural landscape that existed there into an environment modified by man and left an environmental and socioeconomic footprint that would not only be irreversible but would lead to comparatively more severe changes that further impacted the ecosystem of the river, and produced a gradual contamination of its waters. The Hum River reservoir was initially aimed at the production of hydroelectric energy, but it is also used as a source of water for human consumption, to supply tourism and sectors such as fishing and artificial fish breeding for export, in general aspects that can be considered positive for the community. However, the construction of this work considerably affected the riverside forest, impacted the habitat of many species of native fauna both aquatic and terrestrial and produced the forced displacement of a large part of the population that had a life project and prospects of prosperity in their hometown. Obviously, these consequences represent the immediate negative impact that the dam left for Rincón de Bonete, but in the perception of the current population they seem to be, perhaps due to ignorance, insignificant. The large reservoir has attracted investments to develop projects that are proposed as important for the economy of the region and the country such as the production of cellulose pulp. But the environmental ramifications of these activities for ecosystem preservation are still uncertain. The purpose of this work is to show an overview of the ecosystem of the Hum River and the population that developed around it prior to the construction of the dam in Rincón de Bonete, in order to have that information around the evaluation of the nature of the changes, both environmental and social that are reflected in the current landscape of the area. Likewise, the implications of the new hydraulic dynamics of the Hum river post reservoir are discussed regarding geomorphological processes of the flow, particularly those that generated a change in the patterns of erosion and deposition that influenced the geology of the place, revealing Paleozoic sites carrying important fossils for our cultural heritage, that are described for the first time in this work

High PEEP with recruitment maneuvers versus Low PEEP During General Anesthesia for Surgery -a Bayesian individual patient data meta-analysis of three randomized clinical trials

Background: The influence of high positive end-expiratory pressure (PEEP) with recruitment maneuvers on the occurrence of postoperative pulmonary complications after surgery is still not definitively established. Bayesian analysis can help to gain further insights from the available data and provide a probabilistic framework that is easier to interpret. Our objective was to estimate the posterior probability that the use of high PEEP with recruitment maneuvers is associated with reduced postoperative pulmonary complications in patients with intermediate-to-high risk under neutral, pessimistic, and optimistic expectations regarding the treatment effect. Methods: Multilevel Bayesian logistic regression analysis on individual patient data from three randomized clinical trials carried out on surgical patients at Intermediate-to-High Risk for postoperative pulmonary complications. The main outcome was the occurrence of postoperative pulmonary complications in the early postoperative period. We studied the effect of high PEEP with recruitment maneuvers versus Low PEEP Ventilation. Priors were chosen to reflect neutral, pessimistic, and optimistic expectations of the treatment effect. Results: Using a neutral, pessimistic, or optimistic prior, the posterior mean odds ratio (OR) for High PEEP with recruitment maneuvers compared to Low PEEP was 0.85 (95% Credible Interval [CrI] 0.71 to 1.02), 0.87 (0.72 to 1.04), and 0.86 (0.71 to 1.02), respectively. Regardless of prior beliefs, the posterior probability of experiencing a beneficial effect exceeded 90%. Subgroup analysis indicated a more pronounced effect in patients who underwent laparoscopy (OR: 0.67 [0.50 to 0.87]) and those at high risk for PPCs (OR: 0.80 [0.53 to 1.13]). Sensitivity analysis, considering severe postoperative pulmonary complications only or applying a different heterogeneity prior, yielded consistent results. Conclusion: High PEEP with recruitment maneuvers demonstrated a moderate reduction in the probability of PPC occurrence, with a high posterior probability of benefit observed consistently across various prior beliefs, particularly among patients who underwent laparoscopy