THE WINNESHIEK LAGERSTÄTTE, STRATIGRAPHY AND DEPOSITIONAL ENVIRONMENTS OF THE LOWER PORTION OF THE ST. PETER SANDSTONE

文尼希克-拉格斯特，ST下部的地层和沉积环境。爱荷华州自然资源部EAR-0921245Derek BriggsYale University EAR-0922054ABSTRACTA最近在爱荷华州东北部圣彼得砂岩下部的一个局部页岩单元中发现了保存完好的中奥陶世化石动物群--温尼希克动物群。据了解，该动物群仅在一个地方发现，化石保存异常完好，包括软组织(Konservat-Lagerstätte)，并包含各种脊椎动物和无脊椎动物化石。这些动物群保存在精细分层的黑色页岩中，沉积在之前未知的奥陶纪环境中，位于热带劳伦斯海道边缘的一个孤立盆地内。世界上发现的奥陶纪Lagerstätten很少，而温尼西克动物群(已知最古老的)被认为是奥陶纪古生物学中最重要的最近发现之一。对这些特殊化石的保存、存档和研究是必要的，以确保这一独特而重大发现的科学和古生物学遗产。该动物群包含各种稀有且鲜为人知的分类群，包括牙形刺(许多自然组合，其中一些与软组织有关)、有关节的无颌鱼(在奥陶纪最稀有的化石中)、常翅类和其他海龟(属于已知的最古老的化石)、早期叶状甲壳类(许多具有软体保存)、介形类、舌状腕足类、软体动物，以及各种有问题的生物(尤其是蠕虫类？蠕形动物)。动物群的特殊保存将使人们能够详细研究进化历史早期几个鲜为人知的类群的解剖和系统发育关系，特别是节肢动物(海龟、甲壳类)和脊椎动物(牙形刺和茎下口目)。受资助的研究将研究和描述动物群的分类和进化关系，化石产状的沉积学和埋藏学，以及这个独特沉积物的古环境背景。

THE WINNESHIEK LAGERSTÄTTE, STRATIGRAPHY AND DEPOSITIONAL ENVIRONMENTS OF THE LOWER PORTION OF THE ST. PETER SANDSTONEHuaibao P. Lui, Robert M. McKay, and Brian WitzkeIowa Department of Natural ResourcesEAR-0921245Derek BriggsYale UniversityEAR-0922054ABSTRACTA remarkably preserved Middle Ordovician fossil fauna, the Winneshiek fauna, was recently discovered in a localized shale unit in the lower St. Peter Sandstone in northeast Iowa. Known from a single locality, the fauna displays exceptional fossil preservation, including soft tissues (a Konservat-Lagerstätte), and contains a variety of vertebrate and invertebrate fossils. The fauna, preserved in finely laminated dark shale, was deposited in a previously unknown Ordovician environment within an isolated basin along the margin of the tropical Laurentian seaway. There are few Ordovician Lagerstätten identified worldwide, and the Winneshiek fauna (the oldest known) has been recognized as one of the most important recent discoveries in Ordovician paleontology. The preservation, archiving, and study of these exceptional fossils are needed to ensure the scientific and paleontologic heritage of this unique and significant discovery. The fauna contains a variety of rare and poorly known taxa, including conodonts (many natural assemblages, some associated with soft-tissues), articulated jawless fish (among the rarest of Ordovician fossils), eurypterids and other chelicerates (among the oldest known), early phyllocarid crustaceans (many with soft-bodied preservation), ostracods, linguloid brachiopods, mollusks, and a variety of problematic organisms (especially ?worm-like? vermiforms). The exceptional preservation of the fauna will enable detailed studies of the anatomy and phylogenetic relationships of several poorly known groups early in their evolutionary history, particularly within the arthropods (chelicerates, crustaceans) and vertebrates (conodonts and stem gnathostomes). The funded research will study and describe the taxonomy and evolutionary relationships of the fauna, the sedimentology and taphonomy of the fossil occurrences, and the paleoenvironmental setting of this unique deposit.