97 research outputs found

    New digital braincase endocasts of two species of Desmatosuchus and neurocranial diversity within Aetosauria (Archosauria: Pseudosuchia)

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    In the present contribution we revise, figure, and redescribe several isolated braincases of the iconic aetosaur Desmatosuchus from the Placerias Quarry locality, Chinle Formation, Arizona, USA. The detailed study of the isolated braincases from the UCMP collection allowed us to assign them at the species-level and recognize two species of Desmatosuchus for the Placerias Quarry: D. spurensis and D. smalli. The former can be distinguished from the latter by the presence of a transverse sulcus on the parietals, deep median pharyngeal recess on the basisphenoid, almost no gap between the basal tubera and the basipterygoid processes, and the exoccipitals meeting at the midline. The presence of D. smalli at the Placerias Quarry has not been previously reported. Based on the braincases UCMP 27408, 27410, 27407, three new brain endocasts were developed through CT scan images, reconstructing the most complete endocranial casts known for an aetosaur, including the encephalon, cranial nerves, inner ear, and endocranial vasculature. The cranial endocasts also exhibited some differences between both species of Desmatosuchus, with D. spurensis having a distinguishable dural expansion and markedly asymmetric anterior and posterior semicircular canals of the labyrinth. Additionally, the combination of osteological features and the endocranial casts allowed us to identify and discuss the presence of an ossified orbitosphenoid on the anteriormost region of the braincase among aetosaurs. Furthermore, we were able to reinterpret some of the observations made by previous authors on the endocast of the holotype of Desmatosuchus spurensis (UMMP VP 7476) and provide some insight into their neurosensory capabilities.Fil: Von Baczko, Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Desojo, Julia Brenda. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Gower, David J.. Natural History Museum; Reino UnidoFil: Ridgely, Ryan. Ohio University; Estados UnidosFil: Bona, Paula. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Witmer, Lawrence. Ohio University; Estados Unido

    Chapter sixteen: Rodents and other vertebrate invaders in the United States

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    Contents 16.1 Introduction 381 16.2 Assessing impacts of rodents and other vertebrate invaders 385 16.3 Accounts of some important vertebrate invaders 38616.3.1 Norway rant (Rattus norvegicus) 38616.3.2 Roof Rat (Rattus rattus) 38716.3.3 Polynesian rat (Rattus exulans) 38816.3.4 House mouse (Mus Musculus) 38816.3.5 Nutria (Myocastor coypus) 38916.3.6 Gambian giant pouched rat (Cricetomys gambianus) 39016.3.7 Feral swine (Sus scofa) 39016.3.8 Small Indian Mongoose (Herpestes javanicus) 39116.3.9 Rock pigeon (Columba livia) 39216.3.10 House sparrow (Passer domesticus) 39316.3.11 European starling (Sturnus vulgaris) 39316.3.12 Monk parakeet (Myiopsitta monachus) 39416.3.13 Brown tree snake (Boiga irregularis) 39516.3.14 Burmese python (Python molurus bivittatus) 39616.3.15 Coqui frog (Eleutherodactylus coqui) 39716.3.16 Sea lamprey (Petromyzon marinus) 39716.3.17 European and Asian carp (Cyprinidae) 398 16.4 Offshore Threats 399 16.5 Discussion 400 Acknowledgements 401 References 40

    Chapter sixteen: Rodents and other vertebrate invaders in the United States

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    Contents 16.1 Introduction 381 16.2 Assessing impacts of rodents and other vertebrate invaders 385 16.3 Accounts of some important vertebrate invaders 38616.3.1 Norway rant (Rattus norvegicus) 38616.3.2 Roof Rat (Rattus rattus) 38716.3.3 Polynesian rat (Rattus exulans) 38816.3.4 House mouse (Mus Musculus) 38816.3.5 Nutria (Myocastor coypus) 38916.3.6 Gambian giant pouched rat (Cricetomys gambianus) 39016.3.7 Feral swine (Sus scofa) 39016.3.8 Small Indian Mongoose (Herpestes javanicus) 39116.3.9 Rock pigeon (Columba livia) 39216.3.10 House sparrow (Passer domesticus) 39316.3.11 European starling (Sturnus vulgaris) 39316.3.12 Monk parakeet (Myiopsitta monachus) 39416.3.13 Brown tree snake (Boiga irregularis) 39516.3.14 Burmese python (Python molurus bivittatus) 39616.3.15 Coqui frog (Eleutherodactylus coqui) 39716.3.16 Sea lamprey (Petromyzon marinus) 39716.3.17 European and Asian carp (Cyprinidae) 398 16.4 Offshore Threats 399 16.5 Discussion 400 Acknowledgements 401 References 40

    Are chimpanzees really so poor at understanding imperative pointing? Some new data and an alternative view of canine and ape social cognition

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    There is considerable interest in comparative research on different species’ abilities to respond to human communicative cues such as gaze and pointing. It has been reported that some canines perform significantly better than monkeys and apes on tasks requiring the comprehension of either declarative or imperative pointing and these differences have been attributed to domestication in dogs. Here we tested a sample of chimpanzees on a task requiring comprehension of an imperative request and show that, though there are considerable individual differences, the performance by the apes rival those reported in pet dogs. We suggest that small differences in methodology can have a pronounced influence on performance on these types of tasks. We further suggest that basic differences in subject sampling, subject recruitment and rearing experiences have resulted in a skewed representation of canine abilities compared to those of monkeys and apes

    The Evolution of Bat Vestibular Systems in the Face of Potential Antagonistic Selection Pressures for Flight and Echolocation

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    PMCID: PMC3634842This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Long Beach Earthquake and Protection Against Future Earthquakes -- Summary of Report by Joint Technical Committee on Earthquake Protection, Dr. Robert A. Millikan, Chairman

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    To the Public of the Pacific Southwest: In response to official requests from many representative technical and civic organizations, the Joint Technical Committee on Earthquake Protection was organized after the earthquake of March 10, 1933 to consider ways and means of minimizing loss of life and property damage in the event of another earthquake of equal or greater intensity. We now present to you, in the form of this summarized report, our belief as to the seismic hazard in this region and our opinion as to the proper balance between the degree of protection to be afforded life and property and the cost of providing such protection. We sincerely hope that the lessons of the Long Beach earthquake will not be forgotten as were the lessons which should have been fixed indelibly in the minds of all by the earthquakes of the past. Joint Technical Committee on Earthquake Protection. Robert A. Millikan, Chairman. June 7-1933

    Radiographic manifestations of experimental aluminum toxicity in growing bone

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    To evaluate the effect of aluminum on growing bone in the presence of normal renal function, the following experiment was performed. Eight littermate pair-fed pigs (5 weeks old) were randomly assigned to one of two study groups: control C, n =4, or aluminum treated Al, n =4. Daily intravenous injections of either aluminum 1.5 mg/kg/day (Al group) or vehicle only (C group) were given during the 8-week duration of the study. The radiographic findings which appeared in the aluminum-treated group and not in the controls consisted of areas of sclerosis in the submetaphyseal regions and the periphery of epiphyses. In addition there was separation of the anterior tibial tubercle. The growth plates did not increase in width despite the presence of osteomalacia and histologic evidence of extensive deposition of aluminum in bone. The area of sclerosis visualized in the radiographs correlated histologically with thickened bony trabeculae. The increased width of these trabeculae is attributable to an increase in primary spongiosum and broadened seams of osteoid.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46782/1/256_2004_Article_BF00356955.pd

    Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina

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    Background: Living birds possess a unique heterogeneous pulmonary system composed of a rigid, dorsally-anchored lung and several compliant air sacs that operate as bellows, driving inspired air through the lung. Evidence from the fossil record for the origin and evolution of this system is extremely limited, because lungs do not fossilize and because the bellow-like air sacs in living birds only rarely penetrate (pneumatize) skeletal bone and thus leave a record of their presence. Methodology/Principal Findings: We describe a new predatory dinosaur from Upper Cretaceous rocks in Argentina, Aerosteon riocoloradensis gen. et sp. nov., that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium. In living birds, these two bones are pneumatized by diverticulae of air sacs (clavicular, abdominal) that are involved in pulmonary ventilation. We also describe several pneumatized gastralia (‘‘stomach ribs’’), which suggest that diverticulae of the air sac system were present in surface tissues of the thorax. Conclusions/Significance: We present a four-phase model for the evolution of avian air sacs and costosternal-driven lung ventilation based on the known fossil record of theropod dinosaurs and osteological correlates in extant birds: (1) Phase I—Elaboration of paraxial cervical air sacs in basal theropods no later than the earliest Late Triassic. (2) Phase II—Differentiation of avian ventilatory air sacs, including both cranial (clavicular air sac) and caudal (abdominal air sac) divisions, in basal tetanurans during the Jurassic. A heterogeneous respiratory tract wit

    Estimating Mass Properties of Dinosaurs Using Laser Imaging and 3D Computer Modelling

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    Body mass reconstructions of extinct vertebrates are most robust when complete to near-complete skeletons allow the reconstruction of either physical or digital models. Digital models are most efficient in terms of time and cost, and provide the facility to infinitely modify model properties non-destructively, such that sensitivity analyses can be conducted to quantify the effect of the many unknown parameters involved in reconstructions of extinct animals. In this study we use laser scanning (LiDAR) and computer modelling methods to create a range of 3D mass models of five specimens of non-avian dinosaur; two near-complete specimens of Tyrannosaurus rex, the most complete specimens of Acrocanthosaurus atokensis and Strutiomimum sedens, and a near-complete skeleton of a sub-adult Edmontosaurus annectens. LiDAR scanning allows a full mounted skeleton to be imaged resulting in a detailed 3D model in which each bone retains its spatial position and articulation. This provides a high resolution skeletal framework around which the body cavity and internal organs such as lungs and air sacs can be reconstructed. This has allowed calculation of body segment masses, centres of mass and moments or inertia for each animal. However, any soft tissue reconstruction of an extinct taxon inevitably represents a best estimate model with an unknown level of accuracy. We have therefore conducted an extensive sensitivity analysis in which the volumes of body segments and respiratory organs were varied in an attempt to constrain the likely maximum plausible range of mass parameters for each animal. Our results provide wide ranges in actual mass and inertial values, emphasizing the high level of uncertainty inevitable in such reconstructions. However, our sensitivity analysis consistently places the centre of mass well below and in front of hip joint in each animal, regardless of the chosen combination of body and respiratory structure volumes. These results emphasize that future biomechanical assessments of extinct taxa should be preceded by a detailed investigation of the plausible range of mass properties, in which sensitivity analyses are used to identify a suite of possible values to be tested as inputs in analytical models

    The mismeasure of ape social cognition

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    In his classic analysis, The Mismeasure of Man, Gould (1981) demolished the idea that intelligence was an inherent, genetic trait of different human groups by emphasizing, among other things, (a) its sensitivity to environmental input, (b) the incommensurate pre-test preparation of different human groups, and (c) the inadequacy of the testing contexts, in many cases. According to Gould, the root cause of these oversights was confirmation bias by psychometricians, an unwarranted commitment to the idea that intelligence was a fixed, immutable quality of people. By virtue of a similar, systemic interpretive bias, in the last two decades, numerous contemporary researchers in comparative psychology have claimed human superiority over apes in social intelligence, based on two-group comparisons between postindustrial, Western Europeans and captive apes, where the apes have been isolated from European styles of social interaction, and tested with radically different procedures. Moreover, direct comparisons of humans with apes suffer from pervasive lapses in argumentation: Research designs in wide contemporary use are inherently mute about the underlying psychological causes of overt behavior. Here we analyze these problems and offer a more fruitful approach to the comparative study of social intelligence, which focuses on specific individual learning histories in specific ecological circumstances
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