51 research outputs found

    Monophyly of pinnipeds

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    31 p. : ill. ; 26 cm.Includes bibliographical references (p. 27-29)."Within the customary tripartite division of pinnipeds a grouping of the Odobenidae (walruses) and Otariidae (sea lions) to the exclusion of the Phocidae (seals) has been almost universally recognized. An anatomical review of features, primarily of the auditory region, however, reveals that odobenids share a significant number of derived characters with phocids. The evidence supporting the traditional otariid/odobenid grouping is examined and is found to consist almost exclusively of primitive, and therefore phylogenetically uninformative, characters. A review of characters that have been proposed as supporting the widely accepted alliance of phocids and mustelids reveals that they fail to provide compelling evidence for pinniped diphyly; the arguments for diphyly are further weakened by acceptance of a phocid-walrus relationship. Some aspects of the cranial morphology of several putative early Miocene otarioids are reviewed, and it is suggested that Pinnarctidion and Allodesmus are actually better regarded as members of a group including phocids and odobenids. Thus, the major morphological gap between the highly derived phocids and their presumed sister group may largely be filled. A cladogram depicting a sister-group relationship between odobenids and phocids, the monophyly of pinnipeds, and the tentative relationships of these fossil taxa is presented"--P. [1]

    Desmostylian skeleton

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    8 p. : ill. ; 26 cm.Includes bibliographical references (p. 7-8)."According to several standard descriptions, desmostylians lack certain specializations shared by proboscideans, sirenians, and hyracoids. These specializations are amastoidy and the serial arrangement of the carpals with the concomitant loss of contact between the lunar and unciform. We argue that original descriptions of desmostylians pertaining to these traits are either in error, or have alternative phylogenetic implications. Hence, comparisons of these conditions do not exclude desmostylians from the superordinal group Tethytheria (proboscideans and sirenians) or the more inclusive Paenungulata (tethytheres and hyracoids)"--P. [1]

    Oligocene mammals from the Andes of central Chile

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    More than 1400 fossil mammal specimens have been collected over the past 20 years through a series of US-Chilean paleontological expeditions in the central Chilean Andes. These fossils derive from volcaniclastic intervals of the Abanico Formation, mostly between 33.5° and 35.5°S latitude. Mammal assemblages from this formation appear to sample at least six late Eocene to early Miocene South American Land Mammal "Ages", including two from Oligocene, the Tinguirirican (early) and Deseadan (late). The hardness of typical Abanico matrix preserves many specimens in excellent condition, but has limited the number available for taxonomic studies due to the extensive preparation time required. The first -discovered and best- characterized Abanico assemblage is Tinguiririca. Nearly half of the species from Tinguiririca have been described, and studies of two groups are forthcoming: notohippid notoungulates and caviomorph rodents. The notohippids include: two new species of Eomorphippus Ameghino; another species, likely new, but poorly represented; and "E." pascuali Simpson, a species distinct from others of that genus. The caviomorphs include a new chinchillid and a new dasyproctid. Several other Abanico assemblages may be at least partly contemporaneous with Tinguiririca. One, in the valley of the Río Cachapoal, includes: Polydolops mckennai Flynn and Wyss (Polydolopidae); Johnbell hatcheri Hitz, Flynn and Wyss (Interatheriidae); Trachytherus Ameghino (Mesotheriidae); Archaeotypotherium Roth, and Protarchaeohyrax Reguero, Croft, Flynn and Wyss ("Archaeohyracidae"); plus several xenarthrans and at least one rodent. Two others, in the Río Maipo drainage, include Santiagorothia Hitz, Reguero, Wyss and Flynn (Interatheriidae), Archaeotypotherium, a mesotheriid notoungulate, possibly an isotemnid notoungulate, and a rodent. Another locality in the same region appears to be younger, potentially Deseadan in age; rodents are present and abundant, and armadillos, hegetotheriid notoungulates, and interatheriid notoungulates also have been identified.Simposio V: Los mamíferos oligocenos de América del Sur: explosión evolutiva de los mamíferos nativos y llegada de los emigrantes africanosFacultad de Ciencias Naturales y Muse

    Azendohsaurus madagaskarensis.

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    126 pages : illustrations, map ; 26 cm.During the Triassic, archosauromorphs became one of the first groups of diapsid reptiles to diversify in terms of body size and morphological disparity in both terrestrial and marine ecosystems across Pangaea. This seemingly rapid divergence, and the numerous unique body plans stemming from it, concomitantly has confounded reconstructions of archosauromorph relationships. Teasing apart homology from homoplasy of anatomical characters in this broad suite of body types remains an enormous challenge with the current sample of taxa. Here, we present the postcranial anatomy of Azendohsaurus madagaskarensis, an early archosauromorph from ?Middle to Upper Triassic strata of Madagascar. Azendohsaurus madagaskarensis is known from nearly the entire skeleton in an ontogenetically variable sample. The holotype locality consists of a monotypic bone bed; preservation ranges from complete but disarticulated bones to articulated sections of the skeleton. Azendohsaurus madagaskarensis embodies an aberrant constellation of archosauromorph features, including an elongated neck, a short, stocky tail, robust limbs, and unexpectedly short digits terminating in large recurved unguals on the manus and pes. Together with the cranium, the postcrania reveal A. madagaskarensis to be another representative of a growing coterie of highly apomorphic and bizarre Triassic archosauromorphs. At the same time, recovery and description of the full anatomy of A. madagaskarensis helps to identify a monophyletic grouping of specialized taxa that includes the North American Late Triassic-aged archosauromorphs Trilophosaurus, Spinosuchus, and Teraterpeton, Indian Pamelaria, and Moroccan Azendohsaurus laaroussii. Moreover, information derived from the skeleton of A. madagaskarensis solidifies the systematic position of these taxa among other archosauromorphs. Using the most comprehensively sampled phylogenetic analysis of early archosauromorphs, we found the clade encompassing the aforementioned taxa as the nearest outgroup of Prolacerta broomi + Archosauriformes. The newly recognized clade containing Azendohsaurus, Trilophosaurus, Spinosuchus, Pamelaria, and Teraterpeton demonstrates high morphological disparity even within a closely related group of archosauromorphs, underscores the polyphyly of protorosaurs (5 prolacertiforms), and suggests that most major divergences within this group occurred in the Triassic. Furthermore, our results indicate that craniodental character states ascribed to a herbivorous diet were much more pervasive across Triassic Archosauromorpha than previously conjectured

    Multiethnic Meta-Analysis Identifies Ancestry-Specific and Cross-Ancestry Loci for Pulmonary Function

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    Nearly 100 loci have been identified for pulmonary function, almost exclusively in studies of European ancestry populations. We extend previous research by meta-analyzing genome-wide association studies of 1000 Genomes imputed variants in relation to pulmonary function in a multiethnic population of 90,715 individuals of European (N = 60,552), African (N = 8429), Asian (N = 9959), and Hispanic/Latino (N = 11,775) ethnicities. We identify over 50 additional loci at genome-wide significance in ancestry-specific or multiethnic meta-analyses. Using recent fine-mapping methods incorporating functional annotation, gene expression, and differences in linkage disequilibrium between ethnicities, we further shed light on potential causal variants and genes at known and newly identified loci. Several of the novel genes encode proteins with predicted or established drug targets, including KCNK2 and CDK12. Our study highlights the utility of multiethnic and integrative genomics approaches to extend existing knowledge of the genetics of lung function and clinical relevance of implicated loci

    Multiethnic meta-analysis identifies ancestry-specific and cross-ancestry loci for pulmonary function

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    Nearly 100 loci have been identified for pulmonary function, almost exclusively in studies of European ancestry populations. We extend previous research by meta-analyzing genome-wide association studies of 1000 Genomes imputed variants in relation to pulmonary function in a multiethnic population of 90,715 individuals of European (N = 60,552), African (N = 8429), Asian (N = 9959), and Hispanic/Latino (N = 11,775) ethnicities. We identify over 50 additional loci at genome-wide significance in ancestry-specific or multiethnic meta-analyses. Using recent fine-mapping methods incorporating functional annotation, gene expression, and differences in linkage disequilibrium between ethnicities, we further shed light on potential causal variants and genes at known and newly identified loci. Several of the novel genes encode proteins with predicted or established drug targets, including KCNK2 and CDK12. Our study highlights the utility of multiethnic and integrative genomics approaches to extend existing knowledge of the genetics of l

    Genetic Control of Mosquitoes: population suppression strategies

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    Over the last two decades, morbidity and mortality from malaria and dengue fever among other pathogens are an increasing Public Health problem. The increase in the geographic distribution of vectors is accompanied by the emergence of viruses and diseases in new areas. There are insufficient specific therapeutic drugs available and there are no reliable vaccines for malaria or dengue, although some progress has been achieved, there is still a long way between its development and actual field use. Most mosquito control measures have failed to achieve their goals, mostly because of the mosquito's great reproductive capacity and genomic flexibility. Chemical control is increasingly restricted due to potential human toxicity, mortality in no target organisms, insecticide resistance, and other environmental impacts. Other strategies for mosquito control are desperately needed. The Sterile Insect Technique (SIT) is a species-specific and environmentally benign method for insect population suppression, it is based on mass rearing, radiation mediated sterilization, and release of a large number of male insects. Releasing of Insects carrying a dominant lethal gene (RIDL) offers a solution to many of the drawbacks of traditional SIT that have limited its application in mosquitoes while maintaining its environmentally friendly and species-specific utility. The self-limiting nature of sterile mosquitoes tends to make the issues related to field use of these somewhat less challenging than for self-spreading systems characteristic of population replacement strategies. They also are closer to field use, so might be appropriate to consider first. The prospect of genetic control methods against mosquito vectored human diseases is rapidly becoming a reality, many decisions will need to be made on a national, regional and international level regarding the biosafety, social, cultural and ethical aspects of the use and deployment of these vector control methods

    On "retrogression" in the evolution of the Phocinae and phylogenetic affinities of the monk seals. American Museum novitates ; ; no. 2924.

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    38 p. : ill. ; 26 cm.Bibliography: p. 36-38
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