Fossil plants are regard to be excellent proxies to trace paleoclimatic and paleoatmospheric changes. The vegetational response to changing paleoclimate and paleoatmospheric conditions has already been known for a long time and is well documented for the Paleogene of central Europe. Methods such as the Coexistence Approach (CA) and the Climate Leaf Analyses Multivariate Program (CLAMP) analyze the composition of fossil plant assemblages. Changes in paleoclimate and CO2 through time can be tracked also via changes in morphometric parameters such as leaf area, leaf size and leaf shape or epidermal (cuticular) parameters as for instance stomata density (SD), stomata index (SI) and stomata size. The multivariate gas exchange model combines morphometric and cuticular parameters, together with assumed paleoclimate conditions and physiological data of nearest living equivalents to determine paleo-CO2. Plants show differences in morphological, morphometric and cuticular parameters, not only in response to overall changes in CO2 and climate, but also due to their immobility and dependency on light intensity, water availability and soil conditions at the respective site. In this study leaf traits of both Rhodomyrtophyllum reticulosum and Platanus neptuni from 23 sites in Germany, Austria and the Czech Republic covering a time span from the late early Eocene to the early Miocene of central Europe are investigated. Alongside the stratigraphic range of the data set, which allows for tracing long-term variations in the respective parameters, sites of different depositional facies types (maar deposits, marine deposits and fluvial-lacustrine deposits) were included. It has been proven that the investigation of single species and their correspondence to global and regional paleoclimatic and paleoatmospheric shifts has to be done considering differences in the respective depositional setting and thus habitat. Regional effects influence the peculiarity of leaf traits greatly which implies that regional and site related patterns partly overweigh global correspondences. The weak correlation of leaf trait changes to global changes in paleoclimate and CO2 implies that the long-lived species Rhodomyrtophyllum reticulosum and Platanus neptuni are not suitable to track these changes due their high plasticity and adaptability. The long stratigraphic range of the investigated species therefore point out the high adaption potential which by implication leads to a lower correspondence to global paleoclimatic changes. The determination of crucial leaf traits and their response to overall changes in paleoclimate and CO2 hampers the fact that the fossil record bears mainly elements present in azonal vegetation which is caused by predominantly burial of fossils in aquatic bodies. Hence, long-lived species could have been survived these remarkable changes in climate from the end of the Early Eocene Climatic Optimum to the Oligocene icehouse world due to their occurrence in azonal assemblages, buffering global effects in climate variability to a certain degree. The investigation of long-lived fossil species therefore has to be done by coincident consideration of the composition of the whole plant assemblage, which reflects both azonal and partly zonal vegetation of the respective time interval.

Fossil plants are regard to be excellent proxies to trace paleoclimatic and paleoatmospheric changes. The vegetational response to changing paleoclimate and paleoatmospheric conditions has already been known for a long time and is well documented for the Paleogene of central Europe. Methods such as the Coexistence Approach (CA) and the Climate Leaf Analyses Multivariate Program (CLAMP) analyze the composition of fossil plant assemblages. Changes in paleoclimate and CO2 through time can be tracked also via changes in morphometric parameters such as leaf area, leaf size and leaf shape or epidermal (cuticular) parameters as for instance stomata density (SD), stomata index (SI) and stomata size. The multivariate gas exchange model combines morphometric and cuticular parameters, together with assumed paleoclimate conditions and physiological data of nearest living equivalents to determine paleo-CO2. Plants show differences in morphological, morphometric and cuticular parameters, not only in response to overall changes in CO2 and climate, but also due to their immobility and dependency on light intensity, water availability and soil conditions at the respective site. In this study leaf traits of both Rhodomyrtophyllum reticulosum and Platanus neptuni from 23 sites in Germany, Austria and the Czech Republic covering a time span from the late early Eocene to the early Miocene of central Europe are investigated. Alongside the stratigraphic range of the data set, which allows for tracing long-term variations in the respective parameters, sites of different depositional facies types (maar deposits, marine deposits and fluvial-lacustrine deposits) were included. It has been proven that the investigation of single species and their correspondence to global and regional paleoclimatic and paleoatmospheric shifts has to be done considering differences in the respective depositional setting and thus habitat. Regional effects influence the peculiarity of leaf traits greatly which implies that regional and site related patterns partly overweigh global correspondences. The weak correlation of leaf trait changes to global changes in paleoclimate and CO2 implies that the long-lived species Rhodomyrtophyllum reticulosum and Platanus neptuni are not suitable to track these changes due their high plasticity and adaptability. The long stratigraphic range of the investigated species therefore point out the high adaption potential which by implication leads to a lower correspondence to global paleoclimatic changes. The determination of crucial leaf traits and their response to overall changes in paleoclimate and CO2 hampers the fact that the fossil record bears mainly elements present in azonal vegetation which is caused by predominantly burial of fossils in aquatic bodies. Hence, long-lived species could have been survived these remarkable changes in climate from the end of the Early Eocene Climatic Optimum to the Oligocene icehouse world due to their occurrence in azonal assemblages, buffering global effects in climate variability to a certain degree. The investigation of long-lived fossil species therefore has to be done by coincident consideration of the composition of the whole plant assemblage, which reflects both azonal and partly zonal vegetation of the respective time interval.

Aus Patagonien lagen bisher wenige Daten zu paläoökologischen Veränderungen und zur Paläobiodiversität an der Kreide-Paläogen (K/Pg)-Grenze vor. Um diese Lücke zu schließen, wurden in den argentinischen Provinzen Neuquén und Chubut zahlreiche Profile im Bereich der K/Pg-Grenze detailliert beprobt. Während einer Planktonkrise, wie sie für die K/Pg-Grenze angenommen wird, werden für benthische Mollusken folgende Entwicklungen erwartet: 1. eine Abnahme der Individuenzahlen der Benthosorganismen, 2. eine Abnahme der vom Plankton als Nahrungsquelle direkt abhängigen Organismen, 3. eine Abnahme der Benthonten mit planktotrophen Larvalstadien, 4. eine Abnahme der mittleren Körpergröße der Individuen benthischer Faunengemeinschaften und 5. eine Abnahme der Organismen mit hoher Stoffwechselrate bzw. aktiver, mobiler Lebensweise. Tatsächlich waren die hungerresistenten Gruppen der Nuculoida (flach-infaunale Depositfresser) und der Lucinidae (Chemosymbionten) im Danium signifikant häufiger als im Maastrichtium, während der Faunenanteil der Suspensionsfresser im Danium im Vergleich zum Maastrichtium signifikant niedriger ist. In den Faunengemeinschaften des Daniums von Bajo de Añelo konnten Abnahmen der Individuenzahlen, der mittleren Mobilität und der mittleren Größe festgestellt werden. Die beobachteten paläoökologischen Veränderungen zeigen somit eine Selektivität, die sich auch in der Paläobiodiversitätsdynamik widerspiegelt. Auch hier sind Suspensionsfresser, die direkt vom Planktonangebot abhängig sind, stärker betroffen als Chemosymbionten und flach-infaunale Depositfresser. Die Aussterberaten für Bivalven sind mit 28% moderat. Insgesamt sind die festgestellten Selektivitätsmuster konsistent mit den zu erwartenden Folgen einer Planktonkrise. Trotz einiger regionaler Unterschiede handelte es sich um ein globales Ereignis an der K/Pg-Grenze, das Nord- und Südhalbkugel gleichermaßen betroffen hat. / From Patagonia only a few data on palaeoecological changes and on palaeobiodiversity at the Cretaceous/Paleogene (K/Pg)-boundary are available so far. Therefore detailed samples in different K/Pg-sections in the Argentinian provinces of Neuquén and Chubut were taken to increase the data set for this region. The following trends are expected from a crisis of primary productivity in the aftermath of the K/Pg-boundary: 1. a reduction in the number of individuals of benthic organisms, 2. a decrease in the relative abundance of organisms which rely directly on photosynthesis, 3. a lower proportion of individuals with planktotrophic larval stages, 4. a reduction in the average body size of individuals within palaeocommunities and 5. an increased abundance of organisms with low metabolic rates or inactive lifestyles. In fact the proportion of the starvation-resistant groups of the Nuculoida (shallow-infaunal deposit feeders) and Lucinidae (chemosymbionts) were significantly higher in the Danian compared to the Maastrichtian. In contrast to this, the proportion of suspension feeders in the palaeocommunities was significantly lower in the Danian in comparison with the Maastrichtian. In the Danian benthic assemblages of the Bajo de Añelo area, a decrease in number of individuals, mean mobility and mean size was recognised after the K/Pg-boundary. Thus the palaeoecological changes display a selectivity, which is also reflected in the palaeobiodiversity. Suspension feeders, which depend directly on plankton particles from the water column, show higher extinction rates than chemosymbionts and shallow-infaunal deposit feeders. The extinction rates of Patagonian bivalves are moderate (28%). Overall, the recognized selectivity patterns are consistent with the expected aftermath of a crisis in primary productivity. Despite some local differences, the results argue for a global event at the K/Pg-boundary during which the northern and southern hemispheres were similarly affected.

Impaktite des Chicxulubkraters wurden petrographisch (Polarisationsmikroskopie, REM, KL) und chemisch (RFA, TRFA, PGE, EMS) untersucht, um das Verhalten von Ejekta während des atmosphärischen Transports zu erforschen. Die proximalen Impaktite der UNAM-7 Bohrung bestehen aus einer suevitischen Brekzie (222.2 bis 384.4 m) und einer basalen, polymikten Brekzie mit geringem Silikatschmelzanteil. Letztere beinhaltet Evaporit-Megablöcke und Karbonatschmelzpartikel; Zersetzung von Kalzit und Anhydrit ist durch Entgasungsbläschen indiziert. An der distalen Kreide-Paläogen Grenze von El Guayal (520 km SW vom Kraterzentrum) beinhaltet eine 10 m mächtige suevitische Abfolge in einer oberen Untereinheit akkretionäre Lapilli und darüber eine Toneinheit. Das Auftreten von Karbonatschmelzen mit der PGE-angereicherten Impaktorkomponente in der Toneinheit belegt den Zusammenhang der K-P Grenze mit dem Chicxulub-Impakt. Die folgenden Stadien können für die Ablagerung und Alteration der Ejekta unterschieden werden: (1) Ein Hochgeschwindigkeitsauswurf beschleunigte Zersetzungsprodukte und initiierte einen Gasstrom. (2) Karbonatschmelzen wurden mit Anhydrit-Megablöcken ausgeworfen und initiierten einen lateral ausbreitenden Ejektavorhang. Kalzitrückreaktionen erhitzte das Material während des Transports. (3) Die Ejektionswolke kollabierte teilweise, wobei der zurückfallende Suevit vom Impaktormaterial, das in die Stratosphäre verteilt wurde, fraktioniert wurde. Die Kombination von Silikatschmelze mit Kalzit initiierte einen heißen, gas-angetriebenen Strom. In einer oberen, moderat temperierten, turbulenten Aschewolke kondensierte Wasserdampf, und durch Akkretion von Asche entstanden akkretionäre Lapilli. (4) Die Impaktorkomponente wurde mit den feinsten Ejektamassen für Wochen bis Jahre abgelagert. (5) Der Transport von Ejekta in der heißen Ejektionswolke induzierte Alterationsprozesse in den Ablagerungen. Es kann geschlussfolgert werden, dass ein gewisser Anteil des CO2 zu Kalzit zurückreagierte, währenddessen SOX Gase vollständig in die Atmosphäre freigesetzt wurden. Diese Beobachtungen inklusive des Auftretens von Karbonatschmelzen unterstützen die Aussage, dass der freigesetzte Anteil von CO2 in die Atmosphäre in der Vergangenheit überbewertet wurde. / Impactites of the Chicxulub crater were studied petrographically (polarisation microscopy, SEM, CL) and chemically (XRF, TXRF, PGE, EMPA) to investigate the evolution of ejecta during transit through the atmosphere. At the proximal UNAM-7 borehole, the sequence of impactites consists of a suevitic breccia (222.2 to 348.4 m) on top of a polymict silicate melt-poor breccia. The latter is intercalated with evaporite megablocks representing an analogue to the Bunte Breccia of the Nördlinger Ries crater. It contains carbonate melt particles; calcite and anhydrite decomposition is indicated by degassing vesicles. At the distal Cretaceous-Palaeogene site of El Guayal (~520 km SW of the crater centre), a ~10 m thick suevitic succession contains at its upper subunit accretionary lapilli and on top a clay unit. Intermixing of calcite with hot silicate melt resulted in recrystallisation and decomposition of calcite. In the clay unit, the presence of carbonate melt spheroids together with the PGE-enriched impactor component links the Chicxulub impact with the K-P boundary. The following stages can be distinguished for the deposition and alteration of the ejecta: (1) Jetting accelerated decomposition products and initiated a vapour flow. (2) Carbonate melts were excavated with anhydrite megablocks and initiated a lateral extending ejecta curtain. Calcite reformations heated the material during transport. (3) The expanding ejecta plume partially collapsed separating the falling suevite from impactor material that had been lifted into the stratosphere. The combination of silicate melt with calcite initiated a hot, gas-driven, basal flow. In an upper, moderately tempered, turbulent ash cloud, steam condensed and accretion of ash-sized material formed accretionary lapilli. (4) The impactor component was deposited with the finest ejecta for weeks to years. (5) The prolonged transport of ejecta in the hot ejecta plume induced alteration processes observed in the deposits. It can be concluded that a certain amount of CO2 has back-reacted to calcite, whereas SOX gases were completely liberated. These observations including the abundant presence of carbonate melts support that the amount of CO2 released to the atmosphere during the Chicxulub impact was overestimated previously.