The Origin and Initial Rise of Pelagic Cephalopods in the Ordovician

BACKGROUND: During the Ordovician the global diversity increased dramatically at family, genus and species levels. Partially the diversification is explained by an increased nutrient, and phytoplankton availability in the open water. Cephalopods are among the top predators of today's open oceans. Their Ordovician occurrences, diversity evolution and abundance pattern potentially provides information on the evolution of the pelagic food chain. METHODOLOGY/PRINCIPAL FINDINGS: We reconstructed the cephalopod departure from originally exclusively neritic habitats into the pelagic zone by the compilation of occurrence data in offshore paleoenvironments from the Paleobiology Database, and from own data, by evidence of the functional morphology, and the taphonomy of selected cephalopod faunas. The occurrence data show, that cephalopod associations in offshore depositional settings and black shales are characterized by a specific composition, often dominated by orthocerids and lituitids. The siphuncle and conch form of these cephalopods indicate a dominant lifestyle as pelagic, vertical migrants. The frequency distribution of conch sizes and the pattern of epibionts indicate an autochthonous origin of the majority of orthocerid and lituitid shells. The consistent concentration of these cephalopods in deep subtidal sediments, starting from the middle Tremadocian indicates the occupation of the pelagic zone early in the Early Ordovician and a subsequent diversification which peaked during the Darriwilian. CONCLUSIONS/SIGNIFICANCE: The exploitation of the pelagic realm started synchronously in several independent invertebrate clades during the latest Cambrian to Middle Ordovician. The initial rise and diversification of pelagic cephalopods during the Early and Middle Ordovician indicates the establishment of a pelagic food chain sustainable enough for the development of a diverse fauna of large predators. The earliest pelagic cephalopods were slowly swimming vertical migrants. The appearance and early diversification of pelagic cephalopods is interpreted as a consequence of the increased food availability in the open water since the latest Cambrian

Contributions to the Geology of Foxe Land, Baffin Island

19-76http://deepblue.lib.umich.edu/bitstream/2027.42/48183/2/ID020.pd

Die Sicherung der alten Messpfeiler und ihre Rekonstruktion auf dem Dach von Gebaeude A17

Available from TIB Hannover: RR 6134(97-04) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

CHAMP PhaseB - Executive Summary

The small satellite mission CHAMP was initiated and is primarily funded by the German Space Agency (DARA) as a lead project for the East German space industry. It is defined in its main mission goals by researchers of the GeoForschungsZentrum Potsdam (GFZ), and is conducted under lead of GFZ in cooperation with the German Aerospace Establishment (DLR) and the industry. After completion of an initial feasibility study (Phase A) and of the project's definition/specification phase (Phase B), followed by a two months redesign phase (Phase #DELTA#B), CHAMP is supposed to enter into Phase C/D in late 1996. CHAMP as a geoscientific mission with a multi-purpose and complementary payload shall substantially contribute to one of the basic research objectives of studies of planet Earth, that is, to the determination of the composition, structure, and dynamics of the solid planet, its oceans and atmosphere, and its surrounding envelope of charged particles and fields. CHAMP being one element in a timely sequence of Earth observations and platforms, satellites, and mini-satellites could be a contributor to the acquisition of global, synoptic and long-term measurements of global processes through space and ground instrumentation. CHAMP shall fulfil the criteria of a small satellite mission, i.e., only a few years of development time through the usage of existing sensors and commercial spacecraft subsystem components, and reduced costs through protoflight approach, reduced quality standards and test efforts. The most challenging parts of the CHAMP mission are the variety of payload components especially the accelerometer and the magnetometers, each one with demanding environmental requirements. It is designed to observe both the gravitational as well as the magnetic potential from one platform in order to get a complementary scientific payback. The GPS-receiver on-board CHAMP being employed for gravity field recovery, simultaneously will perform atmosphere and ionosphere profiling by Earth limb sounding. It is also for the first time a three-axes accelerometer will be flown to measure with a required accuracy of 10"-"8 m/s"2 the non-gravitational forces, e.g. air drag, perturbing the satellite's motion. (orig.)SIGLEAvailable from TIB Hannover: RR 6134(96/13) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman