The role of trachea, lungs and airsacs in temperature control in sauropods as inferred from finite element and air-flow analysis.

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Allometric estimates of morphological and physiological respiratory parameters obtained in the first and second funding periods have lead to the conclusions that a) an avian style lung is not only likely in sauropods, but that it easily would have met the metabolic needs of a rapidly growing and active juvenile animal at low energetic cost and b) the presence of voluminous airsacs and a long neck could have worked together to control gigantothermic hyperthermy. The goal of the present study is to develop a finite element analysis (FEA)-based thermodynamic model and apply it to allometrically estimated values for the volume and surface area of airsacs and trachea in order to test the hypothesis that the anatomy of the avian-like respiratory system could have provided a key to preventing hyperthermy caused by the scaling of body surface vs body volume. We shall begin by critically testing current gigantothermy models, including most recent data on atmospheric temperature, oxygen partial pressure and relative humidity in areas inhabited by sauropods as well as growth rates, and heat production due to cellular metabolism, digestive activity, fermentation and muscular activity. Second we shall generate a range of reasonable estimates of the surface area of the trachea, lung and air sacs as well as temperature gradients, and combine them with coefficients for thermal conductance, We shall then estimate heat transfer by a novel application of FEA. Finally we shall calculate flow patterns in the trachea and depending on the prevalence of turbulent or laminar flow, estimate evaporative cooling and temperature ventilation-dependent temperature control.