Planktic foraminiferal distribution and paleotemperature reconstruction for the last 560 kyr of ODP Hole 165-999A from the Carribean Sea

Faunal analyses of planktonic foraminifera and upper-water temperature reconstructions with the modern analog technique are studied and compared to themagnetic susceptibility and gamma ray logs of ODP Core 999A (western Caribbean) for the past 560 kyr in order to explore changes in paleoceanographic conditions in the western Caribbean Sea. Long-term trends in the percentage abundance of planktonic foraminifera inODP Core 999Asuggest two hydrographic scenarios: before and after 480 ka.High percentage abundances of Neogloboquadrina pachyderma and Globorotalia inflata, low abundances of Globorotalia menardii and Globorotalia truncatulinoides, low diversity, and sea-surface temperatures (SST) under 24 °C are typical characteristics occurring from 480 to 560 ka. These characteristics suggest a "shallow" well-oxygenated upper thermocline and the influx of nutrients by either seasonal upwelling plumes and/or eddy-mediated entrainment. The second scenario occurred after 480 ka, and it is characterized by high and fluctuating percentage abundances of Neogloboquadrina dutertrei, G. truncatulinoides, G. menardii, Globigerinita glutinata, Globigerinella siphonifera, and Globigerinoides ruber; a declining trend in diversity; and large SSTs. These characteristics suggest a steady change from conditions characterized by a "shallow" thermocline and chlorophyll maximum to conditions characterized by a "deep" thermocline (mainly during glacial stages) and by more oligotrophic conditions. The influence of the subtropical North Atlantic on the upper thermocline was apparently larger during glacial stages, thus favoring a deepening of the thermocline, an increase in sea-surface salinity, and a dramatic reduction of nutrients in the Guajira upwelling system. During interglacial stages, the influx of nutrients from the Magdalena River is stronger, thus resulting in a deep chlorophyll maximumand a fresher upper ocean. The eddy entrainment of nutrients is the probable mechanism responsible of transport from the Guajira upwelling and Magdalena River plumes into ODP 999A site.

Distribution of trace fossils and ichnofabric indices in ODP holes of Leg 119

Trace fossils and ichnofabric were examined from cores of Late Cretaceous to Quaternary age recovered from the Kerguelen Plateau, Indian Ocean. Nearly all of the strata are completely bioturbated, with ichnofabric index 6 most commonly recorded. Preserved discrete trace fossils include Chondrites, Planolites, Zoophycos, and Thalassinoides. A continuous Cretaceous/Tertiary boundary section preserved at ODP Site 738 occurs within a 15-cm-thick interval of laminated sediments. The lack of bioturbation indicates the disappearance of bioturbating organisms from the seafloor, possibly as a result of the same factors that caused the mass extinction or changes in other environmental conditions - most probably, bottom-water oxygen concentrations.

20 movies of x-ray tomograms of different Alpinia fossils

The fossil floras described by Dieter MAI and Harald WALTHER are invaluable for understanding the past plant diversity in Europe, and provide important information on the occurrence of taxa in the fossil record that is critical for evolutionary studies. Among the taxa they recognized were seeds assigned to the extant genus Alpinia ROXB. (Zingiberaceae, Zingiberales). We reinvestigated 28 specimens that were assigned to Alpinia arnensis (CHANDLER) MAI, Alpinia cf. arnensis, and Alpinia bivascularis MAI from the Ypresian (lower Eocene) of the UK, upper Eocene of Germany, and lower Miocene of Germany using non-destructive synchrotron-based X-ray tomography to reveal internal anatomy. None of the samples studied show an anatomy consistent with extant Alpinia or even Zingiberales. The fossils lack the globose shape, often striate external surface, seed coat structure, operculum, and micropylar collar seen in all Alpinia, and lack the chalazal chamber seen in many Alpinia species. Two specimens from the lower Miocene of Germany showed the structure of fruits of Caricoidea CHANDLER (Cyperaceae) with a single-layered exocarp, thick mesocarp, and sclerified endocarp. The other specimens are recognized as Carpolithes albolutum nom. nov. (incertae sedis) from the Ypresian of the UK, C. phoenixnordensis sp. nov. (incertae sedis) from the upper Eocene of Germany, C. bivascularis comb. nov. (incertae sedis) from the lower Miocene of Germany as well as indeterminate tegmens from the lower Miocene of Germany. This reinvestigation demonstrates that there is, as yet, no confirmed fossil record for the extant genus Alpinia. Furthermore, at least four different taxa are recognized from what had been two extinct species, enhancing our understanding of these important European Cenozoic carpofloras.