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

PIs在中太平洋山脉ODP 865孔底部附近的一片30厘米厚的泥岩中发现了一种独特的上阿普tian/下阿普bian泻湖脊椎动物化石lagerstate，该泥岩夹在海洋岛屿玄武岩基之间，在沉积时约为110 Ma，位于太平洋中部，远离所有大陆。这一发现代表了中太平洋地区白垩纪爬行动物遗骸的唯一已知记录，也是太平洋地区已知最古老的鳄鱼遗骸。到目前为止，他们已经找到了一颗原始的1厘米长的鳄鱼牙齿，其他几颗保存完好的小鳄鱼牙齿，代表各种喂养策略的鱼牙齿，鱼鳞，以及目前尚未确定的脊椎动物骨头。与这些相关的是陆生植物残骸、苔藓虫、琥珀、淡水藻类残骸、牡蛎和介形虫。黄铁矿、海绿石丰富，介形类对环境敏感，显示出低氧条件下受限制的海洋古环境。该沉积物有可能产生其他白垩纪脊椎动物的遗骸，如其他海洋爬行动物，鸟类，翼龙和陆地岛屿动物。为了最大限度地减少对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系统来构建该岩心段的高分辨率3D图像。这种成像将使他们能够定位和提取其他脊椎动物遗骸，从核的工作一半，并查看所有脊椎动物遗骸在档案核的一半，不能被破坏取样。CT成像也将使pi能够研究沉积结构，从而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探岩心中，对这些沉积物使用ct扫描将证明它在寻找其他岩心中可能的脊椎动物遗骸方面的有用性。这项研究的意义在于，它将为生活在泻湖古环境中的白垩纪脊椎动物动物群提供一个独特的、前所未有的视角，该环境与任何其他已知的白垩纪和大陆爬行动物遗骸都有很大的不同。这将为我们理解脊椎动物进化、古生态学和古迁移提供一个独特的视角。这项研究完成后，从这个核心中提取的脊椎动物遗骸将永久保存在德克萨斯州自然科学中心，该中心位于德克萨斯州奥斯汀的德克萨斯州纪念博物馆。CT图像将被保存在美国国家科学基金会支持的位于奥斯汀的德克萨斯大学数字形态学图书馆中。ODP核心的一半永久档案将存储在德克萨斯农工大学的综合海洋钻探计划的墨西哥湾沿岸储存库中。

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.