Collaborative/RUI Research: Stable Isotope Reconstruction of North American Terrestrial Environments during the Late Cretaceous

合作/RUI 研究：白垩纪晚期北美陆地环境的稳定同位素重建

• 批准号: 0319041
• 负责人: Raymond Rogers
• 金额: $ 6.16万
• 依托单位: Macalester College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0319041&HistoricalAwards=false
• 关键词: Collaborative; RUI; Research; Stable; Isotope

EAR-0319041ABSTRACTSummary The overall goal of this project is to use carbon and oxygen isotope ratios of vertebrate fossil remains from the Late Cretaceous of North America to study terrestrial ecology, hydrology, and climate. Preliminary isotope data from dinosaur tooth enamel has been obtained, and carbon isotope ratios vary from locality to locality and among dinosaur taxa. Based on what is known about modern terrestrial vertebrates, it is hypothesized that these differences can be used to investigate environmental change, evolution of C4 plants, and ecological niche partitioning by dinosaurs. Oxygen isotope ratios in tooth enamel also vary spatially, and using modern analogs again it is hypothesized that these variations reflects hydrological and climatological differences among localities.In order to test these hypotheses, additional Late Cretaceous dinosaur teeth will be collected from four environmentally and geographically diverse localities: (1) the coastal Judith River Formation and its contemporaneous, upland equivalent (2) the Two Medicine Formation of Montana, (3) the Prince Creek Formation of Alaska, and (4) the Kaiparowits Formation of Utah. Because environmental interpretations of isotopic data can be somewhat ambiguous in the absence of contextual information (e.g., accurate facies associations), detailed stratigraphic and sedimentological analyses of sampled localities will also be conducted, and is integral to this research. By comparing new isotopic and sedimentological data with existing paleontological and paleobotanical information, it will be possible to determine the relationships among isotope ratios and environmental parameters over a range of spatial scales.Intellectual MeritPaleoenvironmental research based on sedimentologically well-constrained dinosaur fossils is a logical extension of that being conducted using mammalian tooth enamel from younger, Cenozoic deposits. Because dinosaurs would have had the same general sources of ingested oxygen and carbon as mammals, it can be assumed that their carbon and oxygen isotope ratios would also be related to environmental parameters. As a result, terrestrial environments during the Mesozoic should now become available for study using stable isotope ratios of vertebrate remains.Stable isotope data collected for the Mesozoic also has potential to complement more traditional paleontological and paleobotanical research. For example, our preliminary findings indicate that carbon isotope ratios differ among herbivorous dinosaur taxa, which is suggestive of resource partitioning. Similarly, high carbon isotope ratios suggest that plants with C4 photosynthetic pathways may have evolved and been abundant during the Mesozoic. In addition, isotope data can be used to test and thus improve model simulations of biome distributions and global climate during this time period. The intellectual ramifications of the proposed research are extensive, and we believe that the project provides a wonderful opportunity to gain novel insights into Late Cretaceous ecosystems.Broader ImpactsAn opportunity to study dinosaurs is an exciting prospect to many students interested in the earth sciences, and this proposed research will be conducted by students at Colorado College and Macalester College as part of their undergraduate education in geology. As such it will serve as an excellent vehicle for learning field and laboratory techniques and interpreting data. In addition, students will hone their communication skills by writing a senior thesis and presenting their results at regional and national meetings. In a more general manner, research described here will serve as a framework for introducing and discussing concepts of sedimentology, isotope geochemistry, and paleontology in a variety of courses.Results of this research will be disseminated to other scientists via published reports in peer-reviewed journals. In addition we plan to make a general summary of our work available to museums so it can be incorporated into exhibits on dinosaurs and Late Cretaceous environments.

EAR-0319041摘要该项目的总体目标是利用北美晚白垩世脊椎动物化石遗骸的碳和氧同位素比来研究陆地生态、水文和气候。从恐龙牙釉质中获得的初步同位素数据已经获得，碳同位素比率在不同地区和不同恐龙类群之间存在差异。基于对现代陆生脊椎动物的了解，假设这些差异可以用来研究环境变化、C4植物的进化以及恐龙的生态位划分。牙釉质中的氧同位素比率也存在空间差异，再次使用现代类似物，假设这些变化反映了不同地区的水文和气候差异。为了验证这些假设，将从四个环境和地理不同的地区收集更多的晚白垩世恐龙牙齿：（1）沿海朱迪思河组及其同时代的高地对应组;（2）蒙大拿州的两个梅迪辛组;（3）阿拉斯加州的王子溪组;（4）犹他州的凯帕罗维茨组。因为在缺乏上下文信息的情况下，同位素数据的环境解释可能有些模糊（例如，精确的岩相组合），还将对取样地点进行详细的地层学和沉积学分析，这是这项研究的组成部分。通过将新的同位素和沉积学数据与现有的古生物学和古植物学信息进行比较，将有可能确定同位素比值和环境参数之间在一系列空间尺度上的关系。由于恐龙和哺乳动物一样，一般都有相同的氧和碳的摄入来源，因此可以假设它们的碳和氧同位素比率也与环境参数有关。因此，中生代的陆地环境现在应该可以利用脊椎动物遗骸的稳定同位素比率进行研究。中生代收集的稳定同位素数据也有可能补充更传统的古生物学和古植物学研究。例如，我们的初步研究结果表明，碳同位素比值在草食性恐龙类群之间存在差异，这表明资源分配。同样，高的碳同位素比值表明，植物与C4光合途径可能已经进化，并在中生代丰富。此外，同位素数据可用于测试，从而改进这一时期生物群落分布和全球气候的模型模拟。这项研究的智力成果是广泛的，我们相信，该项目提供了一个很好的机会，以获得新的见解到晚白垩纪生态系统。更广泛的影响一个机会，研究恐龙是一个令人兴奋的前景，许多学生感兴趣的地球科学，这项拟议的研究将进行的学生在科罗拉多学院和麦卡莱斯特学院的地质学本科教育的一部分。因此，它将作为一个很好的工具，学习现场和实验室技术和解释数据。此外，学生将通过撰写高级论文并在区域和国家会议上展示他们的成果来磨练他们的沟通技巧。在一个更一般的方式，这里描述的研究将作为一个框架，介绍和讨论沉积学，同位素地球化学和古生物学的概念在各种课程。这项研究的结果将通过发表在同行评审的期刊报告传播给其他科学家。此外，我们计划将我们工作的总体总结提供给博物馆，以便将其纳入恐龙和晚白垩世环境的展览中。