Gastropoden aus paläozoischen Geschieben des Kies-Sand-Rückens in der Laerheide (Landkreis Osnabrück)

Aus altpaläozoischen karbonatischen Gesteinen, die als nordische Geschiebe in den Kame-Ablagerungen der Laerheide am Nordrand der Westfälischen Bucht vorkommen, werden ordovizische und silurische Gastropoden beschrieben. Altpaläozoische Gastropoden sind zwar aus verschiedenen südskandinavischen Kalkstein-Geschieben seit langem bekannt, jedoch sind Bestimmungen und Eingruppierungen innerhalb der modernen Gastropoden-Systematik bislang noch nicht erfolgt, so dass auf diesem Gebiet noch erheblicher Nachholbedarf besteht, wozu hiermit ein erster Beitrag geleistet wird.Glacial erratic boulders from kame sediments of the Laerheide in the northern part of the „Westfälische Bucht“ south of Osnabrück have yielded Ordovician and Silurian gastropods. Although early Palaeozoic gastropods are fairly well known from glacial erratics they lack adequate descriptions and classification within the modern systematic framework which is presented here

Paläobiologie und Systematik der neuen Überfamilie Hippocardioidea Pojeta & Runnegar, 1976 (Rostroconchia, Mollusca)

Rostroconchia POJETA, RUNNEGAR, MORRIS & NEWELL, 1972 ist der Name einer ausgestorbenen Molluskenklasse, deren Vertreter vom Kambrium bis ins Perm vorkamen und die sich in drei Ordnungen unterteilt. Der Klasse kommt eine besondere Bedeutung zu, da sie - entsprechend des verwendeten Phylogenie-Konzepts - als Ahnen der Bivalvia und / oder der Scaphopoda angesehen werden und damit eine Schlüsselposition in der Phylogenie der Mollusca einnehmen. Die vorliegende Arbeit beschäftigt sich mit Taxa der so genannten „modernen Rostroconchia“, die zur Ordnung Conocardiida NEUMAYR, 1891 gehören und durch das Vorhandensein eines besonderen Merkmals, der Schleppe, gekennzeichnet sind. Ihre Vertreter kamen vom Ordovizium bis ins Perm vor. Bei der Auseinandersetzung mit der Historie der Ordnung Conocardiida konnten mehrere nomenklatorische Probleme gelöst werden, die unter anderem die Schreibweise der Ordnung und die Festlegung der Typusarten einiger Familien betreffen. Ausgehend von der Revision der Familie Hippocardiidae POJETA & RUNNEGAR, 1976, die bislang sechs Gattungen umfasste, entstand eine neue Überfamilie Hippocardioidea POJETA & RUNNEGAR, 1976 mit drei Familien, zehn neuen Unterfamilien und 29 Gattungen, von denen 16 neu aufgestellt wurden. Die Revision basiert auf Materialsichtungen aus 44 internationalen Museen; Angaben zum bearbeiteten Material finden sich in einer Datenbank (Anlage: CD). Die hier dargelegten paläobiologischen Untersuchungen zur Morphologie, Ontogenie, Schalenmikrostruktur und Lebensweise haben neben neuen Erkenntnissen über das Wachstum von Larvalschale und Dissoconch sowie den mikrostrukturellen Schalenaufbau ergeben, dass hippocardioide Rostroconchia zwingend auf die Symbiose mit photoautotrophen Zooxanthellen angewiesen waren, um ihren Nahrungsgrundbedarf zu decken, und zusätzlich Detritus aufnahmen. Diese Zweigleisigkeit der Ernährung ermöglichte der Gruppe, trotz der ursprünglichen Beschränkung auf Lebensräume in flachmarinen Schelfregionen, geeignete Nischen zu besiedeln und gegenüber den biomechanisch effizienteren Bivalvia während des späteren Abschnitts des Paläozoikums konkurrenzfähig zu bleiben. Die hier angestellten phylogenetischen Überlegungen fordern eine erneute Auseinandersetzung mit den bekannten Theorien und den bislang bekannten Fossilfunden; die Teilergebnisse der Arbeit stützen jedoch eher das Phylogenie-Konzept von PEEL (1991a, b) als das von RUNNEGAR & POJETA (1974), welches ihrer Monografie über die Klasse zugrunde liegt (POJETA & RUNNEGAR 1976). Der Ansatz einer paläobiogeografischen Analyse ergab, dass die letzten Vertreter der Überfamilie im mittleren Perm aufgrund der Reduktion ihrer Lebensräume in Folge der Entstehung von Pangaea ausstarben

Hershey Medical Center Technical Workshop Report: Optimizing the design and interpretation of epidemiologic studies for assessing neurodevelopmental effects from in utero chemical exposure

Neurodevelopmental disabilities affect 3-8% of the 4 million babies born each year in the U.S. alone, with known etiology for less than 25% of those disabilities. Numerous investigations have sought to determine the role of environmental exposures in the etiology of a variety of human neurodevelopmental disorders (e.g., learning disabilities, attention deficit-hyperactivity disorder, intellectual disabilities) that are manifested in childhood, adolescence, and young adulthood. A comprehensive critical examination and discussion of the various methodologies commonly used in investigations is needed. The Hershey Medical Center Technical Workshop: Optimizing the design and interpretation of epidemiologic studies for assessing neurodevelopmental effects from in utero chemical exposure provided such a forum for examining these methodologies. The objective of the Workshop was to develop scientific consensus on the key principles and considerations for optimizing the design and interpretation of epidemiologic studies of in utero exposure to environmental chemicals and subsequent neurodevelopmental effects. (The Panel recognized that the nervous system develops post-natally and that critical periods of exposure can span several developmental life stages.) Discussions from the Workshop Panel generated 17 summary points representing key tenets of work in this field. These points stressed the importance of: a well-defined, biologically plausible hypothesis as the foundation of in utero studies for assessing neurodevelopmental outcomes; understanding of the exposure to the environmental chemical(s) of interest, underlying mechanisms of toxicity, and anticipated outcomes; the use of a prospective, longitudinal cohort design that, when possible, runs for periods of 2-5 years, and possibly even longer, in an effort to assess functions at key developmental epochs; measuring potentially confounding variables at regular, fixed time intervals; including measures of specific cognitive and social-emotional domains along with non-cognitive competence in young children, as well as comprehensive measures of health; consistency of research design protocols across studies (i.e., tests, covariates, and analysis styles) in an effort to improve interstudy comparisons; emphasis on design features that minimize introduction of systematic error at all stages of investigation: participant selection, data collection and analysis, and interpretation of results; these would include (but not be limited to) reducing selection bias, using double-blind designs, and avoiding post hoc formulation of hypotheses; a priori data analysis strategies tied to hypotheses and the overall research design, particularly for methods used to characterize and address confounders in any neurodevelopmental study; actual quantitative measurements of exposure, even if indirect, rather than methods based on subject recall; careful examination of standard test batteries to ensure that the battery is tailored to the age group as well as what is known about the specific neurotoxic effects on the developing nervous system; establishment of a system for neurodevelopmental surveillance for tracking the outcomes from in utero exposure across early developmental time periods to determine whether central nervous system injuries may be lying silent until developmentally challenged; ongoing exploration of computerized measures that are culturally and linguistically sensitive, and span the age range from birth into the adolescent years; routine incorporation of narrative in manuscripts concerning the possibility of spurious (i.e., false positive and false negative) test results in all research reportage (this can be facilitated by detailed, transparent reporting of design, covariates, and analyses so that others can attempt to replicate the study); forthright, disciplined, and intellectually honest treatment of the extent to which results of any study are conclusive--that is, how generalizable the results of the study are in terms of the implications for the individual study participants, the community studied, and human health overall; confinement of reporting to the actual research questions, how they were tested, and what the study found, and avoiding, or at least keeping to a minimum, any opinions or speculation concerning public health implications; education of clinicians and policymakers to critically read scientific reports, and to interpret study findings and conclusions appropriately; and recognition by investigators of their ethical duty to report negative as well as positive findings, and the importance of neither minimizing nor exaggerating these findings

Late Early Devonian Rostroconchia (Mollusca) from Hamar Laghdad (Morocco)

The late Early Devonian rostroconch fauna from the Amerboh Group of Bou Tchrafine in the Hamar Laghdad area is described. The few specimens are assigned to the genera Hoareicardia and Barrandeicardia within the Hippocardiidae of the Hippocardioidea. The material confirms the difficulties in recognizing different shell layer architecture in conocardiid rostroconchs, which is a prerequisite for specific determination. The presence of Hoareicardia in the late Early Devonian of Morocco denotes the distribution of the genus in both the northern (Laurussia) and southern (Gondwanan) shelf margins of the Rheic Ocean, and Barrandeicardia furthermore provides evidence of a probable connection with the highly diverse rostroconch assemblages of Perunica and Armorica

Shallow marine Rostroconchia (Mollusca) from the latest Devonian (Strunian) and their significance for rostroconch life style and evolution

The rostroconch fauna of the uppermost part of the Devonian (Strunian, Etroeungt) comes from a sand-/siltstone succession of the northern flank of the Velbert Anticline, western Germany. The few specimens most probably represent one species of the Hippocardioidea and one of the Conocardioidea without definite determination. The material confirms the difficulties in recognizing different shell layer architecture in conocardiid rostroconchs. The presence of rostroconchs in the Strunian documents a continuous evolutionary lineage from the abundant Middle Devonian rostroconch assemblages to the even more abundant rostroconch associations of the Mississippian. Three hippocardiid specimens are preserved in former life position with the anterior part of the conch oriented almost vertically within the sediment and the hood almost parallel with the former sediment surface, thus, perfectly confirming earlier suggestions on hippocardiid life style

Significance of abrasion patterns in Recent pectinoid bivalve shells

Abrasion, a taphonomic process of three-dimensional alteration and destruction of skeletal morphology after death of the animal and abidance in the Taphonomic Active Zone (TAZ), causes characteristic alteration and destruction patterns in Recent and fossil bivalve shells. We describe abrasion in shells of the Recent bivalves Aequipecten opercularis (Linnaeus) and Mimachlamys varia (Linnaeus) from high-energy macrotidal sandy beaches of Brittany (western France), the Algarve (Portugal) and Wales (UK). Following a revised, comprehensive description of the original shell morphology characteristic external and internal alteration is documented. We demonstrate that taxonomically relevant characters are reduced, altered considerably or even obliterated by abrasive processes which make a correct identification of the respective specimen difficult or impossible. Fracture specimens of abraded and non-abraded shells were analysed to test the role of shell microstructure within the abrasion process. Examples of abrasion in fossils are compared with the Recent material. Knowledge and consideration of abrasion patterns should avoid that new taxa, especially in the fossil record, are established on the basis of abrasion stages

Facies and palaeoecology of the late Visean Actinopteria Black Shale Event in the Rhenish Mountains (Germany, Mississippian)

The isochronous, mid-Brigantian (latest Visean) Actinopteria Black Shale is intercalated in between upper Visean calciturbidites within the northern part of the Rhenish Mountains (Germany). It shows characteristic mass-occurrences of the eponymous bivalve Ptychopteria (Actinopteria) lepida (Goldfuss). The case study of a classical, exceptionally well-preserved outcrop in the Ludenscheid Syncline documents the facies and palaeoecology of this event horizon. Hitherto, sediments had been regarded as deep-marine anoxic deposits, resulting from pelagic rain. Now, microfacies analysis of the mostly silicified mudstones revealed a heterogeneous sedimentary facies, showing ample evidence of current-driven micro-event deposits regarded as mud turbidites. Various but simple ichnofabrics indicate mostly dysoxic conditions of the soupy sediment. Discussion of palaeobiological constraints proves the earlier assumed pseudoplanktic mode of life for Ptychopteria (Actinopteria) lepida and contradicts epibenthic colonisation by that bivalve. Mass-occurrence might be a compaction artefact, but occurrence on few distinct bedding planes in an interval several centimetres thick is related to an extraordinary complete sedimentary record that protected the paper pectens from erosion. This variant of a taphonomic epibole is termed maximum completeness epibole. In the case of the Actinopteria Shale, in sequence stratigraphic terms a transgressive systems tract, this bioevent is postulated to represent the maximum flooding surface with minimum sedimentary input and reworking