Maria Barbacka

Sun and shade leaves in two Jurassic species of Pteridosperms

Abstract Two types of leaves were observed in Komlopteris nordenskioeldii (Nathorst) Barbacka and Ctenozamites cycadea (Berger) Schenk. The differences relate both to morphological and cuticular features and correspond with characters of sun and shade leaves in Angiosperms. This feature is discussed for the first time in Pteridosperms.

GREGUSS'S MORPHOGENERA OF HOMOXYLOUS FOSSIL WOODS : A TAXONOMIC AND NOMENCLATURAL REVIEW

After Gothan and Eckhold, Greguss is perhaps the most prolific author of names of morphogenera for fossil woods. Mainly a neoxylologist, he wrote world-famous books (Greguss, 1955a, 1959, 1967) about both softand hardwoods. Neoxylology was always his main subject of research (Gulyas, 1984) but in the 1940s, encouraged by Elemer Vadasz of the Hungarian Geological Survey, he began to study fossil woods as well.

European Jurassic floras: statistics and palaeoenvironmental proxies

Abstract 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.

Relationships between ecosystems and plant assemblages as responses to environmental conditions in the Lower Jurassic of Hungary and Romania

Abstract Two Early Jurassic localities, the Mecsek Mts in Hungary and Anina in Romania, are similarly significant and both floras are of autochthonous/paraautochthonous origin. In the Early Jurassic the Hungarian locality was a delta plain; the Romanian locality was an intramontane depression filled predominantly by a braided river system. The floristic composition of the two localities (52 genera, 120 species), although superficially similar (25 common genera), differs at species level (only 9 common species) as well as in the proportions of taxa in major plant groups. These differences can be explained by differences in environmental conditions resulting from palaeogeographic and topographic factors. Based on previous and recent studies, alpha diversity as well as statistically (DCA, PCA) differentiated ecogroups are compared and discussed. For common species, the GLM method was used to classify them to particular environmental response types. Their environmental requirements in both ecosystems are evaluated. Some of the shared species showed different preferences at the localities, explainable by their broad ecological tolerance.

A palaeoenvironmental reconstruction based on palynological analyses of Upper Triassic and Lower Jurassic sediments from the Holy Cross Mountains region

ABSTRACT The material for this study was taken from various sites in the Holy Cross Mountains: Studzianna, Huta OP-1 and Przysucha P-3 (bore cores), and Odrowąż (geological outcrop). Palynological and palynofacial analyses were used to reconstruct the Upper Triassic and Lower Jurassic vegetation and palaeoenvironment of that area. Samples from all the sites are characterised by having majority of terrestrial particles. The slides were dominated by translucent phytoclasts and small opaque phytoclasts. Pollen grains and spores were also present. The presence of marine palynomorphs was not confirmed in the samples from any of the sites, dinoflagellate cysts did not occur, and there were no foraminiferal test linings. The Sporomorph EcoGroup (SEG) model (Abbink 1998) was applied to characterise the ecological types of the plant assemblages. The most frequently occurring sporomorphs were assigned to Upland, Lowland and River SEGs. Stratigraphical changes in each of the SEGs indicate differences in climatic conditions. The floristic composition of the Studzianna, Huta and Odrowąż localities inferred from sporomorphs differs somewhat from the composition reconstructed from macroremains.

Ferns of the Lower Jurassic from the Mecsek Mountains (Hungary): taxonomy and palaeoecology

Ferns are the most diverse group in the Early Jurassic plant assemblage of the Mecsek Mountains in southern Hungary and, considering their abundance and diversity, are an important element of the flora. Five families were recognized so far from the locality; these are, in order of abundance, the Dipteridaceae (48% of collected fern remains), Matoniaceae (25%), Osmundaceae (21%), Marattiaceae (6%) and Dicksoniaceae (three specimens). Ferns are represented by 14 taxa belonging to nine genera: Marattiopsis hoerensis, Todites princeps, Todites goeppertianus, Phlebopteris angustiloba, Phlebopteris kirchneri Barbacka and Kustatscher sp. nov., Matonia braunii, Thaumatopteris brauniana, Clathropteris meniscoides, Dictyophyllum nilssoni, Dictyophyllum rugosum, Cladophlebis denticulata, Cladophlebis haiburnensis, Cladophlebis roessertii, and Coniopteris sp. Ferns from the Mecsek Mts. are rarely found in association with other plants. They co-occur mostly with leaves of Nilssonia, leaflets of Sagenopteris, and rarely with other plants. The most commonly co-occurring fern species is P. kirchneri Barbacka and Kustatscher sp. nov. According to our statistical approach (PCA, Ward cluster analysis), the fern taxa cluster in four groups corresponding to their environmental preferences, determined by moisture and disturbance. Most taxa grew in monospecific thickets in disturbed areas; a few probably formed bushes in mixed assemblages, whereas one taxon, P. kirchneri, probably was a component of the understorey in a stable, developed succession of humid environments.