Bone Phosphate Isotopic Patterns of Modern and Extinct Terrestrial Vertebrates

恐龙缺乏有效的温度控制，是恒温动物还是吸热恒温动物，这个问题对它们的生活史、进化、在陆地生态系统中占据主导地位以及最终灭绝具有重要意义。关于恐龙的恒温行为已经积累了大量的证据，包括脑大小、进食机制、古生物地理学、姿势和步态、行为、骨骼组织学和捕食者/猎物关系（Carroll, 1988; Weishample et al., 1990）。这些研究改变了人们对恐龙的普遍看法，它们现在被认为是活跃的动物，尽管它们被认为是变温动物或大规模恒温动物（Ostrom, 1980）。在资助（EAR91-06660）的初始阶段，我们研究了一种新的高精度18O同位素技术在骨磷酸盐分析中的应用。利用岩心体和四肢之间的同位素差异以及磷酸盐古温度方程，可以计算出相对体温差异，从而确定化石动物是异温动物还是恒温动物。在分析的13种恐龙中，所有恐龙似乎都是恒温的，只有一种侏罗纪恐龙表现出地区性的异温性。这些恒温骨同位素模式不能归因于成岩蚀变，因为没有一个标本在骨磷酸盐与结构碳酸盐或方解石胶结物共存相之间具有同位素平衡（共存相测试）。该提案寻求资金，通过与NCSU兽医学院合作，扩大我们的现代骨同位素数据库，研究5种现代目标物种。该物种还将提出扩大我们的化石数据库，以完成我们对不同恐龙分支的调查，并在兽脚类和阿根廷三叠纪组合中寻找恒温动物的起源。

Barrick 9507992 The question of whether dinosaurs lacked effective temperature control and were heterotherms or were endothermic homeotherms has important implications for their life histories, evolution, rise to dominance in terrestrial ecosystems, and eventual extinction. A great deal of evidence has been amassed regarding dinosaur endothermy which includes brain size, feeding mechanics, paleobiogeography, posture and gait, behaviors, bone histology and predator/prey relationships (Carroll, 1988; Weishample et al., 1990). These studies have changed the general perception of dinosaurs and they are now thought of as active animals, though considered to be ectothermic or mass homeotherms (Ostrom, 1980). During the initial phase of funding (EAR91-06660), we investigated the application of a new high precision 18O isotopic technique for the analysis of bone phosphate. By using the isotopic difference between core body and extremities and the phosphate paleotemperature equation, realtive body temperature differences can be calculated to determine if an fossil animal was a heterotherm or homeotherm. Of the 13 species of dinosaurs analyzed, all appear to be homeotherms with one Jurassic species exhibiting regional heterothermy. These homeothermic bone isotope patterns cannot be ascribed to diagenetic alteration, because none of the specimens have isotopic equilibrium between the co-existing phases of bone phosphate with structural carbonate or calcite cements (co-existing phase test). This proposal seeks funds to expand our modern bone isotope data base by working with the NCSU School of Veterinary Medicine on 5 modern target species. The species will also propose to expand our fossil data base to complete our survey of different dinosaur clades, and also to search for the origins of homeothermy in therapsids and in a Triassic assemblage from Argentina.