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  • Author: Evelyn Kustatscher x
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Abstract

Revision of part of the Middle Jurassic flora of Sardinia, the Krasser collection, stored in Prague (Lovisato B collection), containing 23 fossil taxa of horsetails, ferns, cycadophytes, ginkgophytes and conifers. The conifers are most diverse, followed by cycadophytes and ferns. The composition of this assemblage differs notably from the Lovisato collection stored in Cagliari, suggesting that it might derive from a different stratigraphic level and/or palaeoenvironment. The palaeodiversity of the Middle Jurassic flora of Sardinia increases to 46 fossil taxa with this revision. Cycadolepis sp. Nilssonia sp., Nilssonia sp. cf. N. orientalis, Pagiophyllum sp. and Agathoxylon sp. are described for the first time from the Middle Jurassic of Sardinia.

Abstract

An assemblage of unusual microfossils occurs within an accumulation of plant debris, hyphae, and various types of propagules in the Early Devonian Rhynie chert. Specimens consist of a vesicle with one or more prominent wings (alae) arising from the surface; one wing forms a rim around the equator of the vesicle. The microfossils are interpreted as phycomata of a prasinophycean green alga based on morphological similarities to Pterospermella, a microfossil similar to phycoma stages of the extant Pterosperma (Pyramimonadales). This report represents the third record of phycomata in the Rhynie chert, suggesting that this Early Devonian ecosystem served as habitat to a variety of prasinophyte algae. Moreover, the new microfossils add to the inventory of fossil freshwater representatives of this predominantly marine group of algae.

Abstract

The Laurinswand section in the Rosengarten/Catinaccio Massif (Dolomites, Southern Alps, Italy) covers the Permian–Triassic boundary in a proximal marine setting. The section has been studied for palynology, ostracods and carbonate microfacies. Five microfacies types are defined for the carbonates of the Bellerophon Formation (Changhsingian) in this section. Ostracod assemblages from the upper Bellerophon Formation show a moderate to high diversity and mostly indicate normal marine conditions, with some samples from the upper Casera Razzo Member being dominated by eurytopic forms. The ostracod fauna follows transgressive-regressive trends with low diverse assemblages occurring in the regressive parts. These trends are also reflected in the microfacies and can be assigned to three sequences. Palynological assemblages are dominated by phytoclasts, which is typical for proximal marine environments. Sporomorphs are represented predominantly by bisaccate and asaccate pollen grains and are mostly minor components of the palynofacies. Other minor, but consistent components in the Bellerophon Formation are acritarchs, Reduviasporonites and unidentified possible algae or fungi. The latter are particularly abundant in samples with ostracod faunas indicating restricted conditions. The Werfen Formation (uppermost Permian to Lower Triassic) yielded quantitatively poor palynological assemblages, with one sample from the Tesero Member showing a notable increase in spores and spore tetrads. This is indicative of the so-called “spore spike”, a well-known signal from this interval. One sample from the overlying Mazzin Member demonstrated a high relative abundance of Reduviasporonites, which may be related to mass occurrences of this taxon in the Tesero Member at Tesero and at other localities near the Permian–Triassic boundary. Such a mass occurrence normally pre-dates the spore spike, whereas at the Laurinswand, the former post-dates the latter considerably.

Das Profil an der Laurinswand im Rosengarten/Catinaccio-Massif (Dolomiten, Südalpen, Italien) umfasst die Perm-Trias-Grenze in einem proximalen, marinen Milieu. Das Profil wurde auf Palynologie, Ostrakodenfaunen und Karbonat-Mikrofazies untersucht. Fünf Mikrofaziestypen wurden für die Karbonate der Bellerophon-Formation (Changhsingium) definiert. Ostrakodenvergesellschaftungen aus der oberen Bellerophon-Formation weisen eine mittlere bis hohe Diver-sität auf und deuten überwiegend auf normalmarine Bedingungen hin, allerdings werden einige Proben aus dem oberen Casera-Razzo-Member von eurytopen Formen dominiert. Die Ostrakodenfauna folgt transgressiv-regressiven Trends, wobei weniger diverse Faunen in den regressiven Teilen auftreten. Diese Trends sind auch in der Mikrofazies reflektiert und können drei Sequenzen zugeordnet werden. Palynologische Rückstände werden von Phytoklasten dominiert, was typisch für ein proximales, marines Ablagerungsmilieu ist. Sporomorphe sind vor allem durch bisaccate und asaccate Pollenkörner vertreten und sind meist untergeordnete Komponenten der Palynofazies. Weitere untergeordnete, aber stetig auftretende Komponenten in der Bellerophon-Formation sind Akritarchen, Reduviasporonites und nicht identifizierte, mögliche Algen oder Pilzreste. Letztere sind besonders häufig in Proben, deren Ostrakodenfauna eingeschränkt marine Bedingungen anzeigt. Die Werfen-Formation (oberstes Perm bis Untertrias) lieferte wenige palynologische Rückstände, wobei eine Probe aus dem Tesero-Member einen bemerkenswerten Anstieg in der Häufigkeit von Sporen und Sporen-Tetraden aufwies. Dies ist ein Hinweis auf den sogenannten „spore spike“, ein bekanntes Signal aus diesem Zeitintervall. Eine Probe des darüber liegenden Mazzin-Members beinhaltete eine relativ große Menge an Reduviasporonites, was mit Massenvorkommen dieses Taxons nahe der Perm-Trias-Grenze, im Tesero-Member in Tesero und an anderen Orten, zusammenhängen könnte. Ein solches Massenvorkommen liegt normalerweise unterhalb des „spore spike“, wohingegen es an der Laurinswand deutlich darüber liegt.

Abstract

Recently collected material of the monotypic schizaeaceous fern genus Phialopteris is described including for the first time the in situ spores. The complex nomenclatural history of the type species is discussed, resulting in the designation of the new combination Phialopteris heterophylla (Sternberg ex Göppert, 1836) comb. nov. as type. This delicate fern has so far only been found in the Hettangian of Bavaria (Germany). Along with a comparison with contemporary schizaeaceous ferns and extant members of Schizaeaceae, and with dispersed spores, the possibility that this fern might have been a climbing fern, similar to some living Lygodium species, is briefly discussed.

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.