Body cavity size in fossil chewing herbivores, non-chewing herbivores, and carnivores: Implications for GIT volume and gigantism.

在食草动物中，共生肠道微生物对植物材料的消化是Instera保留率(可用于发酵的时间)和颗粒大小的函数。由于粒度越小，消解速度越快，保留时间和粒度减小可以相互弥补。因此，缺乏减小颗粒大小机制的动物(不咀嚼的恐龙，如蜥脚类、剑龙、甲龙)应该在相对较大的(体积大的)肠道的帮助下，采用较长的Instera保留时间。虽然体型被认为是体腔腔体积和肠道体积的指标，但缺乏定量研究。通过对已灭绝的食草动物和活体动物骨骼的数字捕捉、体型重建和体积计算，我们将检验以下假设：a)食肉恐龙、爬行动物和哺乳动物的体腔/腹腔比它们的食草动物对应的要小，特别是b)非咀嚼的食草恐龙和更原始的爬行动物化石比咀嚼的食草恐龙和哺乳动物有更大的腔体腔。我们预测，体腔的体积是食草动物消化形态生理适应的一个重要变量，恐龙--既有咀嚼形式，也有非咀嚼形式--是这一原理的理想模式生物，在这个参数上比哺乳动物表现出更多的变异性。特别是，我们预测，不成比例的大体腔是蜥脚类的一个决定性特征(尽管缺乏咀嚼，但这促进了食物的高摄取和新陈代谢)。

In herbivores, digestion of plant material by symbiotic gut microbes is a function of both ingesta retention (time available for fermentation) and particle size. Because smaller particle size accelerates digestion rate, retention time and particle size reduction can compensate for each other. Thus, animals lacking a particle size reduction mechanism (non-chewing dinosaurs such as sauropods, stegosaurs, ankylosaurs) should have adopted long ingesta retention times, facilitated by comparatively large (voluminous) guts. Although body shape has been suggested as an indicator for the volume of the coelomic cavity and hence the gut, quantitative investigations are lacking. Using digital capture of mounted skeletons of extinct herbivores and live animals, body shape reconstructions and volume calculations, we will test the hypotheses that a) carnivorous dinosaurs, reptiles, and mammals have a less voluminous coelomic/abdominal cavity than their herbivore counterparts, and in particular that b) non-chewing herbivorous dinosaurs and more primitve fossil reptiles have a more voluminous coelomic cavity than chewing herbivorous dinosaurs and mammals. We predict that the volume of the body cavity is an important variate in herbivore digestive morphophysiological adaptation, with dinosaurs – where both chewing and non-chewing forms exist – being the ideal model organisms for this principle, displaying more variability in this parameter than mammals. In particular, we predict that a disproportionately large body cavity is a decisive characteristic of sauropods (that facilitated a high food intake and metabolism in spite of a lack of mastication).