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

怀保P. Lui, Robert M. McKay，和Brian WitzkeIowa自然资源系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——WINNESHIEK动物群。已知从一个地方，动物群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。这些动物被保存在精细层状的深色页岩中，沉积在一个以前未知的奥陶纪环境中，该环境位于热带劳伦特海道边缘的一个孤立盆地内。在世界范围内发现的奥陶纪Lagerstätten很少，而Winneshiek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发现之一。保存、归档和研究这些特殊的化石是必要的，以确保这一独特而重要的发现的科学和古生物学遗产。动物群包括各种罕见的和鲜为人知的分类群，包括牙形刺（许多自然组合，一些与软组织有关），关节无颌鱼（在最稀有的奥陶纪化石中），广翼类和其他螯合动物（在已知的最古老的化石中），早期层状甲壳类动物（许多有软体保存），介形虫，舌形腕足动物，软体动物和各种有问题的生物（特别是蠕虫样的）。蠕虫状的)。动物群的特殊保存将使人们能够详细研究几个鲜为人知的类群在其进化史早期的解剖学和系统发育关系，特别是在节肢动物（螯足动物、甲壳动物）和脊椎动物（牙形刺动物和茎颌口动物）中。资助的研究将研究和描述动物群的分类和进化关系，化石出现的沉积学和地层学，以及这个独特矿床的古环境背景。

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.