Studies of Carbon and Oxygen in Fossil and Modern Tooth Enamel

9604024 Cerling研究人员将在全球范围内研究化石牙釉质的碳和氧同位素组成，以确定过去2000万年来非洲哺乳动物饮食的变化。 PI已经确定，在大约700万到500万年前，世界上许多地方的马科动物和其他大型哺乳动物的釉质的碳同位素组成发生了巨大的变化。 我们建议：1）研究东非不同哺乳动物群体在过去2000万年中向C4饮食的过渡，包括牛科动物，猪，犀牛和长鼻动物; 2）收集东非生态系统现存哺乳动物的数据，以开发d13 C和d180作为古生态学指标的用途。 PI将使用稳定的碳同位素组成作为这些群体的饮食（因此栖息地）的衡量标准，研究犀牛，长鼻兽，猪和牛科动物谱系中不同生态位的发展。 我们将结合这些动物的形态学变化来研究这种转变。 此外，PI将研究三个不同的社区：图尔卡纳湖附近的半沙漠地区，稀树草原平原社区和赤道森林社区。 森林群落可能会保留一个封闭的树冠信号中的d13 C信号，和资源分配的碳和氧应该是可区分的所有社区。

9604024 Cerling The PIs will study the carbon and oxygen isotopic composition of fossil tooth enamel on a global scale to determine changes in the diets of African mammals over the past 20 million years. The PIs have established that the carbon isotopic composition of enamel from equids and other large mammals changes dramatically between about 7 and 5 million years ago in widespread parts of the world. We propose: 1) to examine the transition to C4 diet in East Africa for the last 20 million years for different mammal groups, including bovids, suids, rhinos, and proboscideans; 2) to gather data on extant mammals from the East African ecosystem to develop the use of d13C and d180 as a paleoecologic indicator. The PIs will examine the development of different ecological niches in rhino, proboscidean, suid, and bovid lineages using the stable carbon isotopic composition as a measure of the diet (hence habitat) of these groups. We will examine the shift in conjunction with morphologic change in these animals. In addition, the PIs will examine three different communities: the semi-desert region near Lake Turkana, a savanna plains community, and an equatorial forest community. Forest communities may preserve a closed canopy signal in the d13C signal, and resource partitioning in carbon and oxygen should be distinguishable in all communities.