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

在第一和第二个资助期获得的形态和生理呼吸参数的异速生长估计得出的结论是：a）鸟型肺不仅可能存在于蜥脚类动物中，而且它可以很容易地以低能量成本满足快速生长和活跃的幼年动物的代谢需要，和B）大气囊和长脖子的存在可能共同控制了体温过高。本研究的目的是开发一种基于有限元分析（FEA）的热力学模型，并将其应用于气囊和气管的体积和表面积的异速生长估计值，以检验这一假设，即鸟类样呼吸系统的解剖结构可能提供了一个关键，以防止由体表与体体积的缩放引起的高热。我们将开始严格测试目前的恒温模型，包括最新的数据，大气温度，氧气分压和相对湿度的地区居住的蜥脚类动物以及生长速度，和热量生产由于细胞代谢，消化活动，发酵和肌肉活动。其次，我们将产生一系列合理的估计的表面积的气管，肺和气囊以及温度梯度，并结合联合收割机的热传导系数，然后我们将估计热传递的一个新的应用有限元分析。最后，我们将计算气管中的流动模式，并根据湍流或层流的流行程度，估计蒸发冷却和温度通风依赖的温度控制。

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.