SGER: Timely Excavation of an Upper Cretaceous Fossil-Lagerstatte, Eastern Alabama

SGER：阿拉巴马州东部上白垩纪化石 Lagerstatte 的及时发掘

• 批准号: 0633839
• 负责人: Charles Savrda
• 金额: $ 2.49万
• 依托单位: Auburn University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0633839&HistoricalAwards=false
• 关键词: SGER; Timely; Excavation; Upper; Cretaceous

TIMELY EXCAVATION OF AN UPPER CRETACEOUS FOSSIL-LAGERSTATTE, EASTERN ALABAMAbyCharles E. Savrda and Ronald D. LewisAuburn UniversityEAR-0633839ABSTRACTThe Ingersoll shale is a thin (~1 m), discontinuous clay lens within the Upper Cretaceous Eutaw Formation exposed on a hillslope on private property near Phenix City, Alabama. Since its initial discovery in late 2003, small-scale excavation of this marginal marine deposit has yielded an extraordinarily rich and well-preserved fossil assemblage. Thus, it is an example of a conservation fossil- lagerstatten, a deposit with unusually well-preserved fossils. The biota includes a diverse flora consisting of plant macrofossils, megaspores, and palynomorphs (including marine dinoflagellates), abundant amber, and a fauna that includes mollusks, arthropods, and vertebrates. Although many of the fossils are carbonized and/or pyritized, certain elements of the assemblage reflect unusual preservation of proteins (e.g., collagen and keratin). These proteinaceous fossils include feathers, which are extremely rare in this part of the fossil record. Within a short time, the exposure will be destroyed as a result of the ongoing housing development by the property owner. NSF funding is allowing excavation of the site to be completed in a rapid and professional manner while this important scientific resource is still available.Like other Lagerstatten, the exceptional preservation of the Ingersoll shale has the potential of making significant contributions to paleobiology and clarifying the conditions under which rare fossils are preserved. With regard to the biota itself, the flora found in the Ingersoll shale is abundant and diverse. Over two dozen genera of plants have been recognized from fossil leaves alone, some of which appear to be essentially unaltered. These can be peeled from the rock and are still somewhat flexible. Plant reproductive bodies such as seeds and cones are preserved three-dimensionally by pyritization and carbonization. Amber occurs commonly in some horizons within the Ingersoll shale, and some amber samples have yielded remains of insects and mites. Some uncompacted plant macrofossils contain in situ amber rods within them; thus, the rare opportunity exists of identifying the amber-producers and establishing plant-insect associations within a community. The feather specimens found in the Ingersoll shale are of particular paleobiological significance. Aside from the spectacular feathered dinosaurs from the Liaoning Province, China, feathers are extremely rare fossils in the Mesozoic. Known occurrences often consist of only one or a few isolated individuals, whereas the Ingersoll shale has already produced three specimens. Because amber has been shown to be the best medium for preserving feathers in detail, the possibility exists of finding extremely well-preserved specimens. Furthermore, other keratin-based tissues, such as beaks and claws/talons as well as collagenous connective tissue of the feather bearers could be preserved. Given the state of preservation of proteinaceous fossil components, further excavation holds promise for discovery of soft-bodied remains, including that of vertebrates such as feathered theropods.

阿拉巴马州东部晚白垩世拉格斯塔特化石的及时发掘Savrda和罗纳德D.摘要英格索尔页岩是上白垩统尤陶组中的一个薄（~1 m）不连续粘土透镜，暴露在亚拉巴马州菲尼克斯市附近的一个山坡上。自2003年底首次发现以来，对这一边缘海相存款的小规模挖掘已经产生了非常丰富和保存完好的化石组合。因此，它是一个保存化石的例子- lagerstatten，一个保存异常完好的化石的存款。该生物群包括一个多样化的植物群，包括植物大化石、大孢子和孢粉形（包括海洋腰鞭毛虫）、丰富的琥珀和一个动物群，包括软体动物、节肢动物和脊椎动物。虽然许多化石是化石和/或黄铁矿化的，但组合中的某些元素反映了蛋白质的不寻常保存（例如，胶原蛋白和角蛋白）。这些蛋白质化石包括羽毛，这在化石记录的这一部分是极其罕见的。在很短的时间内，由于业主正在进行的住房开发，暴露将被摧毁。在NSF的资助下，在这一重要的科学资源仍然可用的情况下，以快速和专业的方式完成了对该遗址的挖掘。与其他拉格斯塔特一样，英格索尔页岩的特殊保存有可能为古生物学做出重大贡献，并澄清稀有化石的保存条件。就生物群本身而言，英格索尔页岩中发现的植物群丰富多样。仅从化石叶子就已经识别出了二十多个植物属，其中一些似乎基本上没有改变。这些可以从岩石上剥离，仍然有些灵活。植物生殖体如种子、球果等通过黄铁矿化和碳化作用得以立体保存。琥珀通常出现在英格索尔页岩中的某些层位，一些琥珀样本已经产生了昆虫和螨的遗骸。一些未压实的植物宏体化石中含有原位琥珀棒;因此，存在识别琥珀生产者和在群落内建立植物-昆虫协会的难得机会。在英格索尔页岩中发现的羽毛标本具有特殊的古生物学意义。除了在中国辽宁省发现的壮观的羽毛恐龙外，羽毛是中生代极为罕见的化石。已知的矿点通常只有一个或几个孤立的个体，而英格索尔页岩已经产生了三个标本。由于琥珀已被证明是保存羽毛细节的最佳媒介，因此存在找到保存非常完好的标本的可能性。此外，可以保留其他基于角蛋白的组织，例如喙和爪/爪以及羽毛承载者的胶原结缔组织。考虑到蛋白质化石成分的保存状况，进一步的挖掘有望发现软体动物的遗骸，包括有羽毛的兽脚亚目等脊椎动物的遗骸。