密度,或比重(SG),生物体对它们的形态有许多重要的影响,函数,生态学,以及活着和死人的其他方面,在估计它们的质量时,特别需要应用尽可能准确的SG值,这本身就是生物的一个关键方面。然而,从未对这一著名的解剖学主题进行过全面的回顾和分析。这是一种努力,手头的数据尽可能广泛,在一些额外的观察的支持下,以及针对密度最少的已灭绝动物的新工作:翼龙和恐龙具有广泛的气动复合体,包括迄今为止对蜥脚类动物最复杂的努力。通常即使通过直接观察也很难确定,解释和利用了获取尽可能好的SG数据的技术,包括对漂浮动物的观察。中性比重(NSG)被认为是呼吸道体积波动的四足动物的最重要值。生物的SGs范围从0.08到2.6,植物组织从0.08到1.39,脊椎动物从大约0.75(一些巨大的翼龙)到1.2(具有沉重的盔甲和/或骨骼)。四足NSG往往比人们普遍认为的要高一些,特别是那些有气囊的兽脚类和蜥脚类恐龙和翼龙,因为呼吸系统的体积通常是在鸟类最大吸入时测量的。还讨论了证据,即过去未正确测定骨骼质量相对于总体质量的比率。
The density, or specific gravity (SG), of organisms has numerous important implications for their form, function, ecology, and other facets of beings living and dead, and it is especially necessary to apply SG values that are as accurate as practical when estimating their masses which is itself a critical aspect of living things. Yet a comprehensive
review and analysis of this notable subject of anatomy has never been conducted and published. This is such an effort, being as extensive as possible with the data on hand, bolstered by some additional observations, and new work focusing on extinct animals who densities are least unknown: pterosaurs and dinosaurs with extensive pneumatic complexes, including the most sophisticated effort to date for a sauropod. Often difficult to determine even via direct observation, techniques for obtaining the best possible SG data are explained and utilized, including observations of floating animals. Neutral specific gravity (NSG) is proposed as the most important value for tetrapods with respiratory tracts of fluctuating volume. SGs of organisms range from 0.08 to 2.6, plant tissues from 0.08 to 1.39, and vertebrates from about 0.75 (some giant pterosaurs) to 1.2 (those with heavy armor and/or skeletons).
Tetrapod NSGs tend to be somewhat higher than widely thought, especially those theropod and sauropod dinosaurs and pterosaurs with air-sacs because respiratory system volume is usually measured at maximum inhalation in birds. Also discussed is evidence that the ratio of the mass of skeletons relative to total body mass has not been properly assayed in the past.