New data about Matonia braunii (Göppert) Harris from the Early Jurassic of Poland and its ecology

Fern remains of matoniacean affinity were found in the Lower Hettangian strata of lacustrine/backswamp origin from the Niekłań PGI 1 borehole (central Poland, Holy Cross Mts.). The preserved fragments have been identified as Matonia braunii (Göppert, 1841) Harris, 1980. The remains suggest a rather small, low-growth plant with palmately compound fronds. The sori contain at least 5 sporangia preserved with well-developed annuli. The spores are triangular, trilete and kyrtomate, with a thin and smooth surface corresponding with dispersed Dictyophyllidites mortoni (de Jersey, 1959) Playford et Dettmann, 1965. Based on the gross morphology of sterile and fertile pinnae, suggestions made by Harris (1980) on the synonymy of Phlebopteris braunii (Göppert, 1841) Hirmer et Hörhammer, 1936 with P. muensteri Schenk, 1867 (Hirmer and Hörhammer, 1936) and their referral to Matonia braunii is proved and confirmed in this paper. The fern occurs in strata indicating a warm and humid climate and approaching transgression resulting in a high water table and the enhanced accumulation of organic matter

Triassic-Jurassic flora of Poland : floristical support of climatic changes

Plant macroremains from five boreholes in Poland were studied. Two of them (Huta OP-1 and Studzianna) from the northern margin of the Holy Cross Mountains, yielded several taxa. In the other three boreholes determinable fossil plants were sporadic, albeit important. Most of the taxa from the Huta OP-1 and Studzianna boreholes are typical of the European Early Jurassic (Hettangian and Sinemurian). Both localities, although close to one another, show quite different taxonomic floral compositions. The Huta OP-1 flora is fern-dominated with the presence of ginkgophytes and conifers (a new species incertae sedis, Desmiophyllum harrisii Barbacka et Pacyna is herein proposed), which would suggest rather wet and warm conditions. This flora is typical of the European Province of the Euro-Sinian Region. In Studzianna the Siberian elements dominate, gymnosperms, mainly Czekanowskiales, which indicate a drier and colder environment.The palaeobotanical data correspond to the results of clay mineral studies, in particular the kaolinite/illite ratio in the source formations. The kaolinite content confirms a decrease in temperature and a reduction in rainfall in the late Early Hettangian and the latest Hettangian in the area

European Jurassic floras : statistics and palaeoenvironmental proxies

The Jurassic floras of Europe show considerable diversity. To examine the extent of this diversity and its possible causes we used multivariate statistical methods (cluster analysis, PCA, NMDS) to compare all significant Jurassic floras in Europe. Data were based on 770 taxa from 46 fossiliferous occurrences (25 units) from France, Germany, Greenland, Hungary, Italy, Norway, Poland, Romania, Scotland, Serbia, Sweden, Switzerland, and the United Kingdom. Statistical analyses were applied at species level and genus level, and also performed for the major plant groups. The genus cladograms show affinities between different localities based on environmental factors, while the cladograms based on species affinities indicate only taxonomical correlations. The study shows that locality age does not seem to be of paramount importance for floral composition

Palaeoenvironmental reconstruction of Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn

Multidisciplinary studies of the Middle–Upper Bathonian ore-bearing clays at Gnaszyn revealed variable palaeoenvi- ronmental conditions during the deposition of this seemingly monotonous sequence. We interpret the conditions in the bottom environment and the photic zone, and also evaluate the influence of the adjacent land areas, based on sedi- mentology, geochemistry, sporomorphs and palynofacies composition, benthic (foraminifera, gastropods, bivalves, scaphopods, echinoderms), planktonic (calcareous nannoplankton, dinoflagellate cysts), and nektonic (sharks) fossils. The Gnaszyn succession originated relatively close to the shore, within reach of an intense supply of terrestrial fine clas- tic and organic particles. The latter are mainly of terrestrial origin and range from 1.5 to 2.5 wt.%. The precise water depth is difficult to estimate but most likely ranges from several tens of metres to a few hundred metres. All fossil groups show minor changes throughout the succession. As the climate seems to have been quite stable during this period we consider sea-level fluctuations to have been the main factor responsible for the changes. The terrestrial input, includ- ing freshwater and land-derived clastic and organic particles (sporomorphs and cuticles), increased during periods of sea-level lowstand. As a consequence, stress conditions (lower salinity, higher nutrient availability, lower water trans- parency) in the photic zone caused blooms of opportunistic planktonic taxa. Furthermore, a faster sedimentation rate led to oxygen depletion and deterioration of the living conditions in the bottom environment due to an increased accumulation of organic matter. As a result, the benthic biota became taxonomically impoverished and commonly dominated by juvenile forms. During periods of high sea level, the source areas were shifted away from the basin, resulting in a decrease in the terrestrial influx, increase in the salinity of surface waters, the appearance of more diverse phytoplank- ton assemblages, a lower sedimentation rate, and an improvement of living conditions at the bottom