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

圣彼得砂岩下部的Winneshiek Lagerstätte、地层和沉积环境最近，在爱荷华州东北部圣彼得砂岩的一个局部页岩单元中，发现了保存完好的中奥陶世动物化石--温尼希克动物群。该动物群在一个单一的地点被发现，显示出特殊的化石保存，包括软组织（Konservat-Lagerstätte），并包含各种脊椎动物和无脊椎动物化石。 动物群，保存在良好的层状黑色页岩，沉积在一个以前未知的奥陶纪环境内的一个孤立的盆地沿着边缘的热带劳伦特海道。 奥陶纪动物群在世界范围内很少被发现，而温尼希克动物群（已知最古老的动物群）被认为是奥陶纪古生物学中最重要的新发现之一。 需要对这些特殊化石进行保护、存档和研究，以确保这一独特而重要的发现的科学和古生物学遗产。 动物群包含各种稀有和鲜为人知的类群，包括牙形刺（许多自然组合，一些与软组织有关），铰接无颌鱼（奥陶纪化石中最稀有的），广翅类和其他螯形动物（已知最古老的），早期叶状甲壳类（许多软体保存），介形类，舌形腕足动物，软体动物，和各种有问题的生物（特别是？蠕虫状的蠕虫状）。 动物群的特殊保护将使详细研究解剖和几个鲜为人知的群体在其进化史的早期，特别是在节肢动物（螯肢类，甲壳类）和脊椎动物（牙形刺和茎颚）的系统发育关系。 受资助的研究将研究和描述动物群的分类和进化关系，化石的沉积学和埋藏学，以及这个独特的存款的古环境背景。

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.