19 Chapters
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6. Reconstructing Body Volume and Surface Area of Dinosaurs Using Laser Scanning and Photogrammetry

Nicole Klein Indiana University Press ePub

STEFAN STOINSKI, TIM SUTHAU, AND HANNS-CHRISTIAN GUNGA

Crucial baseline data in dinosaur paleobiology and for reconstructing dinosaurs as living animals are accurate measurements of one- to three-dimensional features such as length, surface area, and volume. Dinosaur skeletons mounted and on display in museums offer the opportunity to obtain such data and to create digital models of them. These models, in turn, serve as the basis for estimating physiological and other biological parameters. In this chapter, we provide an overview of data capture using laser scanning and photogrammetrical methods and describe the working steps from the captured point clouds of the skeleton to the final volume model. Because dinosaur skeletons are complex objects with irregular structures, laser scanning proved to be much more accurate for capturing their shape than previously used methods such as photogrammetry. The modeling of the body surface area and body volume with digital techniques is also more accurate than established methods that are based on scale models. Here, nonuniform rational B spline (NURBS) curves and CAD software are used to reconstruct the body surface and for surface area and volume calculations.

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3. Dietary Options for the Sauropod Dinosaurs from an Integrated Botanical and Paleobotanical Perspective

Nicole Klein Indiana University Press ePub

CAROLE T. GEE

During the majority of the Mesozoic, from the Triassic to the mid Cretaceous, the food plants of the sauropod dinosaurs were virtually limited to ferns, fern allies, and gymnosperms because the diversification of the angiosperms, which include the broad-leaved trees and grasses of today, only began in the Late Cretaceous. In this chapter, the preferences of the sauropods for one or more of these Mesozoic plant groups are evaluated by means of a survey approach that integrates botanical and paleobotanical data. These data include the growth habits of the nearest living relatives of these plant groups, their habitat, the amount of biomass produced, and the ability to regrow shoots, branches, and leaves after injury through herbivory. The relative quantities of energy and essential nutrients yielded to herbivores with hindgut fermentation, the consumption of the various plant groups by modern herbivores, and the coeval occurrence of sauropods and individual plant groups in the fossil record are other major factors taken into consideration here. As a result of this extensive survey, it appears that Araucaria, Equisetum, the Cheirolepidiaceae (an extinct conifer family), and Ginkgo would have been most accessible, sustaining, and/or preferred sources of food for the sauropods. Moderately accessible, sustaining, and/or commonly encountered plants would have been other conifers such as the Podocarpaceae, Cupressaceae, and Pinaceae. Less commonly browsed by the sauropods, especially by large, fully grown individuals, would have been forest-dwelling ferns such as Angiopteris and Osmunda. The least frequently eaten plants were probably the cycads and bennettitaleans.

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Appendix: Compilation of Published Body Mass Data for a Variety of Basal Sauropodomorphs and Sauropods

Nicole Klein Indiana University Press ePub

In the appendix, published body mass data for a variety of basal sauropodomorphs and sauropods have been compiled. Note the differing results for some taxa, mainly depending on the method used for body mass reconstruction. The different methods used (as described by the authors cited) are coded in the table as follows: 0, method not given; 1, von Bertalanffy equation; 2, 3D mathematical slicing; 3, polynomial technique and volume figures; 4, log transformed (base 10) database consisting of model-based body estimates and measurements of bone dimensions; 5, bone measuring, midshaft femora, and/or humeri circumference; 6, ontogenetic growth curves of dinosaur species, estimated from data on the scaling of maximum growth rates for reptiles and mammals; 7, scale model, water displacement, and volume of living animals scaled up from the model; 8, weighing scale models in air and water, recalculation using a slightly lower overall density (950 kg/m3); 9, 3D stereophotogrammetry, laser scanning of mounted skeletons; 10, estimating cubic meters; 11, considering pneumaticity, reduced neck and tail volume; 12, laser stereophotogrammetry, laser scanning, and 3D reconstruction methods; 13, plasticine scale models, following a skeletal restoration; 14, estimated by personal opinion; 15, ‘‘gathered data’’; 16, modern skeletal reconstructions, numerical estimates of centers of mass.

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14. Rearing Giants: Kinetic–Dynamic Modeling of Sauropod Bipedal and Tripodal Poses

Nicole Klein Indiana University Press ePub

HEINRICH MALLISON

Because of their large body masses, sauropod dinosaurs must have required enormous amounts of plant matter to support their metabolism, even if one assumes a much lower metabolic rate in adults than in extant mammals and birds. Therefore, their methods of food acquisition are of interest, specifically how they procured a sufficient volume of food without expending unlikely large amounts of energy during feeding. Some, if not all, sauropods supposedly could rear up onto their hindlimbs to access food at heights beyond the reach of other herbivores, increasing their feeding envelopes without requiring energetically more costly locomotion. Kinetic–dynamic modeling in comparison with elephants indicates that at least diplodocids could rear easily and for prolonged times without significant exertion, while brachiosaurids were probably not capable of extended upright feeding. Modeling results also suggest that optimizing body shape for rearing by a posterior shift of the center of mass may be detrimental to locomotory abilities.

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7. Body Mass Estimation, Thermoregulation, and Cardiovascular Physiology of Large Sauropods

Nicole Klein Indiana University Press ePub

BERGITA GANSE, ALEXANDER STAHN, STEFAN STOINSKI, TIM SUTHAU, AND HANNS-CHRISTIAN GUNGA

This chapter provides an overview on thermoregulation and the cardiovascular physiology of sauropods on the basis of data obtained by laser scanning and surface modeling of the basal sauropodomorph Plateosaurus engelhardti and the basal macronarian sauropod Brachiosaurus brancai. Nonuniform rational B splines (NURBS) were used to obtain volume estimates of the thoracic cavity, and these estimates correspond well with vital organ masses as determined by allometric modeling. To reach body masses of about 50 metric tons, large sauropods might have had, at least partly during their life span, a high resting metabolic rate, and they might have been endothermic homeotherms to maintain thermoregulative control. Assuming a lack of sweat glands in sauropods, heat balance was likely to be regulated by processes of radiation, convection, and conduction. Heat transfer from the body surface via convection, especially during exercise (hyperthermia), was probably limited, and large bird-like air sacs as part of the lung structures might have served as ‘‘thermal windows’’ to help regulate the temperature. A four-chambered heart would have generated lower pressures in the pulmonary circulation and higher pressures in the systematic regulation. Additional physiological mechanisms such as high oxygen transport capacity, muscular venous pumps, tight skin layers, thick vessel walls, strong connective tissue, precapillary vasoconstriction, low permeability of capillaries to plasma proteins, and digital cushions in the feet were necessary to meet cardiovascular requirements by supporting fluid volume regulation and preventing edema in large sauropods. Thus, in regard to cardiovascular and thermoregulative control, sauropods were highly specialized animals.

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