Morphological Variation of the Forelimb and Claw in Neotropical Sigmodontine Rodents (Rodentia: Cricetidae)

The limbs of mammals exhibit a variety of morphologies that reflect the diversity of their habitats and their functional needs, including subtle structural differences in their distal limb integumentary appendages (hooks, claws, adhesive pads). Little is known about structure and function of claws of sigmodontine rodents. Here, we analyze claw shape and forelimb skeleton morphology of 25 species of sigmodontine rodents with different locomotory types (ambulatory, fossorial, natatorial, quadrupedal saltatorial, and scansorial), taking into account their phylogenetic affinities. Qualitative differences in claw shape were examined using digital photographs, and quantitative measurements were made for length, height, and curvature of the claws of all digits, and dimensions of other forelimb skeletal elements. Our results show that both phylogeny and ecological categories explain substantial components of the morphological variation in sigmodontine rodents. Qualitative analysis reveals that non-specialized forms (ambulatory, quadrupedal saltatorial, and scansorial) tend to have high and strongly curved claws, whereas highly specialized forms (fossorial and natatorial) tend to have elongate and smoothly curved claws. However, the quantitative analysis differentiated the fossorial and scansorial by variables related to claw, and natatorial by variables related to bones of the forelimb. No variables that could differentiate ambulatory or quadrupedal saltatorial forms were found, demonstrating that these forms show a generalized morphological pattern. This study indicates that both historical and ecological factors contribute to the evolution of claw length in these groups.Fil: Tulli, María José. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Carrizo, Luz Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Samuels, J. X.. John Day Fossil Beds National Monument; Estados Unido

Morphology of the axial skeleton of seven bat genera (Chiroptera: Phyllostomidae)

ABSTRACT Here we present detailed descriptions and comparisons of the axial skeleton of seven species of bats belonging to five subfamilies of Phyllostomidae of different trophic guilds. The material examined consisted of 34 complete skeletons of seven species. For five of the studied species, previous descriptions have not been conducted, and for the vampires only limited information is available, so that descriptions for these species are here completed. The axial skeleton has characters that allow grouping of the species phylogenetically of the same subfamily and by feeding habits. At the same time, there are characters that associate species from different subfamilies with different types of diet or ways to obtain food

Tracing the Paleobiology of Paedotherium and Tremacyllus (Pachyrukhinae, Notoungulata), the Latest Sciuromorph South American Native Ungulates – Part II: Orbital, Auditory, and Occipito-Cervical Regions

The caudal cranium and occipito-cervical region, although usually overlooked, are informative about the paleobiology of fossil mammals, allowing inquiry into vision and hearing abilities, as well as head and neck postures. Particularly for Pachyrukhinae, some related features remain unexplored. In this contribution, 22 specimens of Paedotherium and Tremacyllus were analyzed in a mainly qualitative and comparative framework. Pachyrukhines are characterized by having large orbits and hearing cavities, moderate to short necks with generalized morphologies, and S-shape postures. These features allow rejecting some types of specialized digging habits, and support the preference of open or low-humidity environments. Paedotherium typicum is distinguished by the presence of laterally oriented eyes, marked vaulted cranium and predominant short extensor and stabilizing neck muscles, and cervico-occipital-hyoid configurations suitable for ventro-flexed resting posture. These features indicate accentuated frontation and panoramic-vision, upward head postures enhancing substrate perception, and the resistance of impacts during leaping-cursorial locomotion. Conversely, P. bonaerense, and to lesser degree Tremacyllus spp., show less frontation and probably adopted more horizontal head postures. More particularly, stronger ventral and lateral neck and head flexors and extrinsic arm musculature are reconstructed for P. bonaerense, compatible with generalist or scratch-digging habits. Its smaller auditory cavities and stronger ear musculature, compared to the contemporary P. typicum and especially Tremacyllus spp., would indicate larger ears and microhabitat segregation. The integrative analysis proposed here and in the accompanying contribution aims to shed light on convergences with extant models, paleobiology, niche partitioning, and external appearance of the latest rodent-like ungulates.Fil: Ercoli, Marcos Darío. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Alvarez, Alicia. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Youlatos, Dionisios. Aristotle University of Thessaloniki; GreciaFil: Moyano, Silvana Rocio. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Candela, Adriana Magdalena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Preoperative nasopharyngeal swab testing and postoperative pulmonary complications in patients undergoing elective surgery during the SARS-CoV-2 pandemic.

BACKGROUND: Surgical services are preparing to scale up in areas affected by COVID-19. This study aimed to evaluate the association between preoperative SARS-CoV-2 testing and postoperative pulmonary complications in patients undergoing elective cancer surgery. METHODS: This international cohort study included adult patients undergoing elective surgery for cancer in areas affected by SARS-CoV-2 up to 19 April 2020. Patients suspected of SARS-CoV-2 infection before operation were excluded. The primary outcome measure was postoperative pulmonary complications at 30 days after surgery. Preoperative testing strategies were adjusted for confounding using mixed-effects models. RESULTS: Of 8784 patients (432 hospitals, 53 countries), 2303 patients (26.2 per cent) underwent preoperative testing: 1458 (16.6 per cent) had a swab test, 521 (5.9 per cent) CT only, and 324 (3.7 per cent) swab and CT. Pulmonary complications occurred in 3.9 per cent, whereas SARS-CoV-2 infection was confirmed in 2.6 per cent. After risk adjustment, having at least one negative preoperative nasopharyngeal swab test (adjusted odds ratio 0.68, 95 per cent confidence interval 0.68 to 0.98; P = 0.040) was associated with a lower rate of pulmonary complications. Swab testing was beneficial before major surgery and in areas with a high 14-day SARS-CoV-2 case notification rate, but not before minor surgery or in low-risk areas. To prevent one pulmonary complication, the number needed to swab test before major or minor surgery was 18 and 48 respectively in high-risk areas, and 73 and 387 in low-risk areas. CONCLUSION: Preoperative nasopharyngeal swab testing was beneficial before major surgery and in high SARS-CoV-2 risk areas. There was no proven benefit of swab testing before minor surgery in low-risk areas