Non-destructive High Resolution CT-scanning of a Crocodilian-bearing Vertebrate Fossil-Lagerstatte from a 110 Ma Mid-Pacific Drowned Atoll, Ocean Drilling Program (ODP) Site 865

PI在中太平洋山脉ODP 865孔底部附近的海洋岛屿玄武岩岩床之间夹着30 cm厚的泥岩中发现了一个独特的上Aptian/下Albian泻湖脊椎动物化石lagerstatte，该岩床位于太平洋中部，距离所有大陆尽可能远，沉积时间约为110 Ma。这一发现代表了中太平洋地区唯一已知的白垩纪爬行动物遗骸记录，也是太平洋海域已知最古老的鳄鱼遗骸。到目前为止，他们已经恢复了一个原始的1厘米长的鳄鱼牙齿锥，其他几个保存完好的较小的鳄鱼牙齿，代表各种进食策略的鱼牙齿，鱼鳞，以及目前尚未确定的脊椎动物骨骼。与之相关的有陆生植物残骸、孢粉、琥珀、淡水藻类遗骸、牡蛎和介形类。丰富的黄铁矿、绿柱石和环境敏感的介形类，指示一个低氧条件下的局限海相古沉积。这个存款有可能产生其他白垩纪脊椎动物，如其他海洋爬行动物，鸟类，翼龙和陆地岛屿动物群的遗骸。为了最大限度地减少对这少量岩心材料的进一步破坏性采样，PI将使用德克萨斯大学的超高分辨率X射线CT系统来构建该岩心间隔的高分辨率3D图像。这一成像将使他们能够定位和提取其他脊椎动物遗骸从工作的一半核心，并查看所有脊椎动物遗骸在档案核心的一半，不能破坏性采样。CT成像还将使PI能够研究沉积结构，以了解该层的沉积历史。其他近岸海洋和陆地沉积物出现在其他深海钻孔岩芯中，对这一存款进行CT扫描将证明其在寻找其他岩芯中可能的脊椎动物遗骸方面的有用性。一个前所未有的观点白垩纪脊椎动物群生活在泻湖古环境尽可能远离任何其他已知的白垩纪和大陆爬行动物遗骸这将为我们理解脊椎动物进化、古生态学和古迁徙增添一个独特的视角。在这项研究完成后，从这个岩芯中提取的脊椎动物遗骸将永久保存在德克萨斯州奥斯汀的德克萨斯州自然科学中心，该中心设有德克萨斯纪念博物馆。CT图像将存档在德克萨斯大学奥斯汀分校的NSF支持的数字形态学图书馆中。ODP核心的永久档案一半将存储在德克萨斯州A M大学综合海洋钻探计划的墨西哥湾沿岸储存库。

PIs have discovered a unique upper Aptian/lower Albian lagoonal vertebrate fossil lagerstatte in a 30 cm thick mudstone sandwiched between oceanic island basalt sills near the base of ODP Hole 865 in the Mid-Pacific Mountains, which, at the time of deposition about 110 Ma, was located in the middle of the Pacific Ocean about as far away from all continents as possible. This discovery represents the only known record of Cretaceous reptilian remains from the mid-Pacific region, and the oldest known crocodilian remains in the Pacific oceanic realm. So far, they have recovered a pristine 1 cm long cone of a crocodilian tooth, several other well preserved smaller crocodilian teeth, fish teeth representing a variety of feeding strategies, fish scales, and currently unidentified vertebrate bones. Associated with these are terrestrial plant debris, palynomorphs, amber, freshwater algal remains, oysters, and ostracods. Abundant pyrite, glauconite, and environmentally sensitive ostracods, indicate a restricted marine paleoenvironnment with low oxygen conditions. This deposit has the potential of yielding remains of other Cretaceous vertebrates such as other marine reptiles, birds, pterosaurs and terrestrial island fauna. To minimize further destructive sampling of this small amount of core material, PIs will use the ultra-high resolution X-ray CT system at the University of Texas to construct high-resolution 3D images of this core interval. This imaging will allow them to locate and extract other vertebrate remains from the working half of the core, and view all vertebrate remains in the archive core half which cannot be sampled destructively. CT imaging will also enable PIs to study the sedimentary structures in order to understand the depositional history of this layer. Other near-shore marine and terrestrial deposits occur in other deep-sea drill cores, and the use of CT-scanning on this deposit will demonstrate its usefulness in searching other cores for possible vertebrate remains.The significance of this research is that it will provide a unique, unprecedented view of a Cretaceous vertebrate fauna living in a lagoonal paleoenvironment as far removed as possible from any other known Cretaceous and continental reptilian remains. This will add a unique perspective to our understanding of vertebrate evolution, paleoecology and paleomigrations.After completion of this study, the vertebrate remains extracted from this core will be stored permanently at the Texas Natural Science Center, which houses the Texas Memorial Museum, in Austin, Texas. The CT images will be archived in the NSF supported Digital Morphology Library at the University of Texas at Austin. The permanent archive half of the ODP core will be stored at the Gulf Coast Repository of the Integrated Ocean Drilling Program at Texas A&M University.