Charlie A. Hamm, Heinrich Mallison, Oliver Hampe, Daniela Schwarz, Juergen Mews, Joerg Blobel, Ahi Sema Issever &Â Patrick Asbach (2018)
Computed tomography scanning compared to photogrammetry on the example of a Tyrannosaurus rex skull from the Maastrichtian of Montana, U.S.A.
Journal of Paleontological Techniques 21: 1-13Â
ISSN: 1646-5806
Free pdf:
Imaging is crucial to gather scientific data in paleontology. Photogrammetry is currently a frequently used technique for surface imaging, producing high-quality 3D surface data. Clinical computed tomography (CT) scanners are interesting for paleontological research because of their high availability and the potential to image internal structures in addition to the surface. In this study we report the technical effort, workflow and image quality of clinical CT compared to photogrammetry for a large fossil. The fossil investigated in this study is the skull of a Tyrannosaurus rex (MB.R.91216) from the Maastrichtian of Montana, U.S.A., of which 47 bone elements are preserved. CT scanning was technically feasible in all bone elements and 3D models were generated from CT data and photogrammetry. The overall scanning procedure time measured 83 min 51 sec. The overall CT data volume measured 36,265 GB. The overall radiation exposure (DLP) measured 62,313.6 mGy*cm. The total costs were calculated with 243.17â and 408.18â for CT and photogrammetry, respectively. This study shows that a clinical CT scanner can be used for imaging even large paleontological objects with high density. In comparison to CT scanning, the data-capture effort of photogrammetry is directly linked to the size and color of the specimen and to the complexity of its shape. While those factors influence the photogrammetry-based 3D model and the quality of its details, the CT scan is mostly free of these variables. Unlike the acquisition and calculation time in photogrammetry the CT scanning time for large and small objects measures roughly the same, as this method is independent of the specimenâs shape and complexity.ÂÂ
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Thanks to Bill Sellers for bringing this one to my attention:
I. Nesteruk (2018)Â
Tyrannosaurus rex running? Estimations of efficiency, speed and acceleration.Â
Innovative Biosystems and Bioengineering 2(1):42-48Â
DOI: 10.20535/ibb.2018.2.1.120491
Background. The estimations of maximum speed of Tyrannosaurus rex vary from 5-20 m/s and higher and still are the subject of scientific discussion. Some scientists consider T. rex the largest terrestrial superpredator that needed speeds greater than 60 km/h (17 m/s) to capture its prey. Some recent publications indicate that it wasnât able to run at all due to its large mass and significant loads on the skeleton and limit its walking speed to 5-7.5 m/s.Â
Objective. We will try to answer the question of whether large animal or robot sizes are an obstacle to rapid running and to evaluate the maximum possible speed of T. rex.Â
Methods. We will use: a) two energy efficiency indicators - the drag-to-weight ratio or the cost of motion and the recently developed capacity-efficiency (connected with the power-to-weight ratio or metabolic rate); b) the vertical acceleration estimations; c) the available data about the speed, the stride and the leg length of human and animals.
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Results. The drag-to-weight ratio and the capacity-efficiency were estimated for running of different animals and humans. It was shown that the maximal running speed of T. rex may reach the values 21--29 m/s. The values of its vertical acceleration are typical for bipedal running.Â
Conclusions. Large dimensions of Tyrannosaurus rex couldnât be an obstacle to achieving rather high speeds during short intervals of fast running. Such conclusions allow us not to abandon the assertion that the dinosaur was a super-predator. Presented approach could be useful for studying locomotion in modern and fossil animals, human sport activity and for design of fast bipedal robots.Â
Mauricio R. Papini, Julio C. Penagos-Corzo and AndrÃs M. PÃrez-Acosta (2019)
Avian Emotions: Comparative Perspectives on Fear and Frustration.
Frontiers in Psychology (Published 17 January 2019)
Emotions are complex reactions that allow individuals to cope with significant positive and negative events. Research on emotion was pioneered by Darwinâs work on emotional expressions in humans and animals. But Darwin was concerned mainly with facial and bodily expressions of significance for humans, citing mainly examples from mammals (e.g., apes, dogs, and cats). In birds, emotional expressions are less evident for a human observer, so a different approach is needed. Understanding avian emotions will provide key evolutionary information on the evolution of related behaviors and brain circuitry. Birds and mammals are thought to have evolved from different groups of Mesozoic reptiles, theropod dinosaurs and therapsids, respectively, and therefore, their common ancestor is likely to be a basal reptile living about 300 million years ago, during the Carboniferous or Permian period. Yet, birds and mammals exhibit extensive convergence in terms of relative brain size, high levels of activity, sleep/wakefulness cycles, endothermy, and social behavior, among others. This article focuses on two basic emotions with negative valence: fear and frustration. Fear is related to the anticipation of dangerous or threatening stimuli (e.g., predators or aggressive conspecifics). Frustration is related to unexpected reward omissions or devaluations (e.g., loss of food or sexual resources). These results have implications for an understanding of the conditions that promote fear and frustration and for the evolution of supporting brain circuitry.