ALBERT

Description: Mit dem Bekanntwerden der Conodonten in der Literatur (Pander 1856) begann auch die Diskussion um die Stellung dieser Fossilreste im System. Zahlreiche Publikationen beschäftigten sich damit, keine konnte das Problem lösen, keine der Ansichten fand allgemeine und uneingeschränkte Anerkennung. Um so interessanter schien es, als im Sommer 1964 von K. Fahlbusch eine umfangreiche Abhandlung unter dem Titel „Die Stellung der Conodontida im biologischen System“ erschien. F. kommt auf Grund seiner Untersuchungen zu dem Ergebnis, die Conodonten seien Reste fossiler Algen. Diese Ansicht weicht so stark von allen bisher geäußerten Meinungen über die systematische Stellung der conodontentragenden Organismen ab, daß sie eine eingehende kritische Überprüfung des Materials, der gedanklichen Voraussetzungen, der so weit reichenden Schlußfolgerungen und der nachfolgenden Weiterungen des Autors herausfordert. Nachdem Herr Fahlbusch freundlicherweise zwei Verf. (Krebs u. Ziegler) den größten Teil seines Materials vorgeführt hat, soll an dieser Stelle Kritik am Material und an der Hypothese der Algen-Zugehörigkeit geübt werden. Wir sehen uns zu diesem Schritt leider gezwungen, um einer sonst möglichen Übernahme, der Vorstellungen F.’s und ihrem Eingang in die Literatur entgegenzuwirken. Die Verf. sind einer großen Zahl von Kollegen zu großem Dank für Diskussionsbereitschaft und tätige Mithilfe verpflichtet. Besonderer Dank gebührt Dr. H. Werner (Chemiker) und Dr. H. Pietzner (Mineraloge) am Geologischen Landesamt Nordrhein-Westfalen in Krefeld, die den Abschnitt über chemische und röntgenographische Untersuchungsverfahren in der Arbeit Fahlbusch eingehend und fachkundig durcharbeiteten und im Zusammenhang damit — wo es nötig und möglich erschien — auch Kontrolluntersuchungen durchführten. Ebenso sind wir Privatdozent Dr. E. Flügel (Paläontologe), Inst. f. Geologie, TH Darmstadt, für spezielle Hinweisedankbar (s. 〉S. 392).

Description: Evolution of the Caribbean Plate can be modeled by motions about six successive rotation poles. Opening of Cayman Trough has occurred since 49.5 Ma through westward motion of the Caribbean Plate, eastern Greater Antilles and Chortis Block. Before 49.5 Ma, the eastern Greater-Antilles were west of Cuba, and the southeastern margins of Yucatan and the Nicaragua Rise (Chortis) were aligned. From 67.5 to 49.5 Ma the Caribbean Plate rotated clockwise, opening the Yucatan Basin. From 100 Ma to 67.5 Ma, the Caribbean Plate, with Cuba attached, moved along the southeastern margin of Yucatan-Chortis. At 130 Ma it was attached to northwestern South America.

Description: The density of seawater is a complex function of temperature, salinity, and pressure. Because of the non-linearity of the equation of state of seawater, the densities of sea waters having the same temperature and the same salinity differences (with respect to the mean salinity of the ocean) will vary with the mean salinity of the ocean. Although this strange property of seawater is evident in a plot of the equation of state, it has never been considered in trying to reconstruct ancient ocean circulation. These differences in the density field may have caused the ocean to respond differently to atmospheric forcing in the past. The different response may hold the key to understanding "ocean anoxic events" and episodes of large-scale burial of organic carbon and production of petroleum source rocks.

Description: The Late Cretaceous was much warmer than today. There was no significant ice at high latitudes, meridional thermal gradients were low, and continental interiors remained warm during winter. Late Cretaceous atmospheric C02 concentrations were about four times greater than today and an enhanced "greenhouse" effect contributed to the overall warmth of the Late Cretaceous. However , increases in atmospheric C02 tend to increase temperatures at all latitudes and do not explain the very low thermal gradients recognized in the geologic record. Increased poleward ocean heat transport has been cited as a mechanism for maintaining low meridional thermal gradients during the Cretaceous. However , ocean heat transport values larger than the present day are difficult to reconcile. In addition, low meridional thermal gradients suggest sluggish atmospheric circulation, implying that the advection of heat from the warm oceans into the continental interiors was limited. In general, paleoclimate simulations using Atmospheric General Circulations Models (AGCMs) have not been successful in simulating the low meridional thermal gradients and warm winter continental interiors of the Cretaceous, forcing the concept of "equability" to be questioned. Until recently, the physical effects of vegetation on pre-Quaternary climates have largely been ignored. Terrestrial ecosystems influence global climate by affecting the exchange of energy, water, and momentum between the land surface and the atmosphere. In a new approach to pre-Quaternary paleoclimate modeling, Campanian (80 Ma) climate and vegetation have been simulated using a global climate model (GENESIS Version 2.0), coupled to a predictive vegetation model (EVE), resulting in a realistic simulation of Late Cretaceous climate. The predicted distribution of Late Cretaceous vegetation played an important role in the maintenance of low meridional thermal gradients, polar warmth, and equable continental interiors. High latitude forests reduced albedo, especially during snowcovered months, and increased net surface radiation and latent heat flux.