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Based on high-resolution palynological analysis of 680 samples from a core, short-term changes in plant diversity and floristic composition within the Paleogene greenhouse were detected in the lacustrine succession of a lower to middle Eocene maar lake at Messel (Federal State of Hesse, Germany). The microfloristic data show that taxonomic diversity increased rapidly within some decades during recolonization of a volcanically devastated area around the lake. With the establishment of a climax vegetation at the end of recolonization, the maximum in palynological diversity was reached within the crater area. During the following 640 Kyr the composition of the palynospectrum changed only gradually. However, different richness and evenness estimations show that alpha and gamma diversity decreased up to 35%, which can be related to the establishment of an equilibrium stage within the climax vegetation that led to the dominance of an assemblage of self-replacing species. Nevertheless, time-series analysis of alpha-diversity changes within the climax vegetation reveals that orbitally controlled climate change of Milankovitch and sub-Milankovitch order influenced the diversity of the vegetation, resulting in a rise of beta diversity. Based on the composition of the vegetation and comparison to modern analogues, our analysis proves that Eocene paratropical plant diversity increased during periods of slightly higher temperature and precipitation. Therefore, both composition and diversity of the vegetation was highly susceptible to minor-scale, short-term changes in climate, even during equable greenhouse conditions.

Fossilized leaf mines and other traces of phytophagous insects provide a unique window into ecological and evolutionary associations of the past. Leaf-mining flies (Diptera: Agromyzidae) are an important component of the recent leaf-mining fauna, but their fossil record is sparse compared to other mining insect lineages; many putative agromyzid body fossils and traces are dubiously assigned. Agromyzid leaf mines often can be distinguished from those of other insects by the presence of an intermittent, fluidized frass trail that may alternate between the sides of the mine. Here, we describe two new Paleogene leaf mine fossils, Phytomyzites biliapchaensis Winkler, Labandeira and Wilf n. sp. from the early Paleocene of southeastern Montana, USA, occurring in leaves of Platanus raynoldsii (Platanaceae); and Phytomyzites schaarschmidti Wappler n. sp., from the middle Eocene of Messel, Germany, occurring in leaves of Toddalia ovata (Rutaceae). These fossils both exhibit frass trails indicative of an agromyzid origin, and P. biliapchaensis also exhibits associated stereotypical marks identical to damage caused by feeding punctures of extant adult female Agromyzidae prior to oviposition. Phytomyzites biliapchaensis represents the earliest confirmed record of Agromyzidae, and one of the earliest records for the large dipteran clade Schizophora. Plant hosts of both species belong to genera that are no longer hosts of leaf-mining Agromyzidae, suggesting a complex and dynamic history of early host-plant associations and, for the early Paleocene example, an evolutionary, possibly opportunistic colonization in the midst of the ecological chaos following the end-Cretaceous event in North America.

Gastric pellets (i.e., regurgitated indigestible food remains) are rare in the fossil record. Here, we describe three gastric pellets with bird remains from the early Eocene Messel fossil site in Germany. A small, ball-shaped specimen that contains various broken bird bones resembles the pellets of owls and may have been produced by the Messel owl Palaeoglaux artophoron, which would make it the oldest owl pellet identified so far. The two other gastric pellets with bird remains have more elongated shapes and probably stem from snakes or other squamates. Both contain partially articulated bird skeletons, one of which belongs to an undescribed species that is otherwise unknown from the abundant avian fossil record from Messel. The fossil pellets described here therefore not only contribute to a better understanding of the avifauna of Messel, but are also important for reconstructing trophic webs and add to an understanding of the early Eocene Messel ecosystem.

The colors of many animals arise from ordered nanometer-scale variations in tissue structure. Such structural colors—especially those with metallic optical effects—are widespread among modern insects but are preserved rarely in insect fossils. This suggests that a specific set of taphonomic circumstances is required for preservation of structural colors. Here we present the results of the first systematic investigation of the controls on the preservation of structurally colored tissues in fossil insects. Approximately 700 specimens of beetle taxa known to exhibit metallic structural colors were studied from seven Lagerstätten: Randecker Maar (early Miocene), Clarkia (early Miocene), Enspel (late Oligocene), Florissant (late Eocene), Eckfeld (middle Eocene), Messel (middle Eocene), and Green River (middle Eocene). The quality of preservation of metallic colors varies among, and within, these biotas; colors are well preserved in most specimens from Clarkia, Enspel, Eckfeld, and Messel, but are typically poorly preserved in specimens from Randecker Maar and absent in Florissant and Green River. These differences are independent of taxonomy and the age and depositional context of the biotas. Instead, variation among biotas is attributed to differences in their late diagenetic history, in particular the maximum depth to which sediments were buried and the nature of fluid flow, as well as recent weathering. Variations in the quality of structural color preservation among specimens from individual biotas are independent of precise stratigraphic and sedimentological context. These intrabiota variations usually result from differences in the extent of microbial degradation of the cuticle and of recent weathering, but also the mode of curation of specimens. The last of these has important implications for curatorial practice.

Three fossil taxa of megapodagrionid damselflies are described and figured from the Paleogene localities in Europe on the basis of isolated wings. Eckfeldia superstes (Wappler, 2003) gen. nov. is described from the laminated mudstones of middle Eocene age from Eckfeld Maar, Germany. Furagrion jutlandicus (Henriksen, 1922) gen. nov. is recorded from the laminated claystones of lowermost Eocene age from the Ølst and Fur-Formation, Denmark, and an undetermined megapodagrionid damselfly is recognized from middle Eocene strata. Taphonomy and color preservation in the fossils are briefly considered. Characters used for phylogenetic analyses in extant and fossil Megapodagrionidae are discussed. The biogeographic and paleoecological implications of the new European fossils are briefly discussed.

The Nemestrinidae or tangle-veined flies are a small group of brachycerous flies with about 300 extant and fossil species (Evenhuis, 1994). Many of them are large to medium-sized flies with a densely pilose body. They have a unique wing venation with a compound diagonal vein which is an apomorphic character for Nemestrinidae (Yeates, 1994). The diagonal vein comprises elements of veins R, M, and Cu and it crosses the wing obliquely. Adult nemestrinids often occur in open areas and many feed on the nectar of flowers (Richter, 1997). Nemestrinid larvae appear to be internal parasitoids of Orthoptera (grasshoppers) and can even control the population numbers of Acridoidea (Orthoptera: Caelifera); however, the species of Hirmoneura Meigen, 1820 develop in larvae of scarabaeid beetles (Richter, 1997). As far as is known, the female places the eggs in the host's habitat and the first-instar larvae actively search out their host. Larval development takes about 40 days, but there may be a long diapause (inactive period) before 20 to 30 days of pupation take place. Adults live for about 25 to 45 days (Richter, 1997).

Carbon and nitrogen stable isotopic compositions of fossil materials from Lake Messel (47 Ma) in Germany are used to investigate Eocene ecosystem dynamics. Autolithified soft tissues of terrestrial and aquatic vertebrate organisms, as well as plant compression fossils, contain organic material (20–50 wt% C, 1–6 wt% N), which appears to retain precursor compositions. Stable isotopic compositions (δ13C and δ15N) of Messel fossils are similar to those reported for components in modern lacustrine ecosystems. These data show trophically sensible enrichments relative to food sources, reflect multiple feeding strategies for each organism (e.g., omnivory, planctivory, piscivory), and differentiate between benthic and pelagic organic carbon sources. These chemical data broadly confirm existing Messel food web models based on coprolite and gut content analyses. δ13C values for the lacustrine shale range from −30.3 to −26.3‰, pointing to mixed terrestrial and aquatic origins for primary producers in the food web. δ13C values for primary consumers such as insects overlap with those for primary producers but are comparatively enriched in 15N. Secondary and higher consumers (fish, crocodiles, and frogs) are associated with even more positive δ15N values and show a more constrained range of δ13C values. Omnivory appears widespread in both low and high trophic level consumers. Hence, the stable isotopic compositions of Messel fossils are complex and overlap, and must be combined with paleontological investigations in order to be conclusive. This study represents the first comprehensive isotopic reconstruction, featuring tens of components, of an ecosystem of Eocene age. A thorough understanding of trophic structure in Eocene Lake Messel contributes to the global databank of ecological history.

The Middle Eocene (Lutetian) bee faunas of Eckfeld and Messel, Germany are revised. In addition to the previously known Electrapis electrapoides (Lutz), five additional species are recognized. Four new species of the Electrapini (Apidae: Apinae) are described: Electrapis micheneri Wappler and Engel, E. prolata Engel and Wappler, Protobombus pristinus Wappler and Engel, and P. messelensis Engel and Wappler. In addition, the new genus Pygomelissa Engel and Wappler is proposed for Pygomelissa lutetia Engel and Wappler new species, which cannot presently be classified into any tribe of the Apidae. The tribe Megachilini (Megachilidae: Megachilinae) is also recorded from Eckfeld but in the absence of any body fossil. Megachilines include the leaf-cutter bees (Megachile) and from the occurrence of the distinctive semicircular damage they produce in leaves, we conclude that such bees were also present in the fauna. The bee fauna is compared with that of the contemporaneous Baltic amber. As with Baltic amber, the majority of bee specimens are from the advanced eusocial lineages of the corbiculate Apinae. Lastly, comments are made on the phylogenetic and paleobiological significance of the faunas.

A new avian taxon is described from the Middle Eocene of Messel in Germany. This bird closely resembles the Lower Eocene North American Fluvioviridavis platyrhamphus Mayr and Daniels, 2001. Eurofluvioviridavis robustipes n. gen. et sp. and F. platyrhamphus are classified in the new taxon Fluvioviridavidae. These birds exhibit a bauplan that is unknown modern birds in combining a flycatcher-like beak with greatly abbreviated legs. Eurofluvioviridavis is distinguished from Fluvioviridavis by its much stronger toes, indicating that the new Messel species occupied a different ecological niche from its North American relative and that the Fluvioviridavidae were an ecologically diversified group in the Eocene. Despite their morphological distinctness, however, the phylogenetic affinities of the Fluvioviridavidae are still uncertain. Their phylogenetic affinities are evaluated in a cladistic analysis of 96 morphological characters, but the resulting position basal to a cluster of several modern higher level taxa is only weakly supported.

An exploration well drilled at the Middle Eocene fossil site of Messel, near Darmstadt, Germany proved that the famous Messel oil shale was deposited in a maar lake. During a quantitative palynological investigation of the entire succession of lake sediments, a monospecific population of dinoflagellate cysts was encountered. Based on transmitted light and scanning electron microscope (SEM) studies, they are assigned to the new peridinioid taxon Messelodinium thielepfeifferae gen. et sp. nov. because they are acavate and lack distinct apical or antapical horns. The dinoflagellate cysts exhibit considerable intraspecific variation in surface ornamentation. Messelodinium thielepfeifferae gen. et sp. nov. is abundant in sediments of the early holomictic stage of Lake Messel, but generally is reduced in frequency in the oil shale which represents the meromictic stage. These dinoflagellate cysts appear in peak abundances in mass flow and debris flow deposits in which material from the lake shore was transported downslope to the basin center. Thus, major concentrations of Messelodinium thielepfeifferae gen. et sp. nov. occurred in nearshore environments either due to primary population density of the parent motile stage, or due to secondary cyst accumulation by wind and wave action. The dinoflagellate cysts are notably absent in the uppermost 25 m of the core, where Botryococcus dominates. This shift in algal populations is interpreted as a response to changes in the chemistry of the water body.