Jiří Kvaček

Two cycads Nilssonia mirovanae sp. nov. and Pseudoctenis babinensis J.Kvaček from the Cenomanian of the Bohemian Cretaceous Basin (the Czech Republic) as indicators of water stress in the palaeoenvironment

Abstract

Nilssonia mirovanae sp. nov. is described from the Late Cretaceous Cenomanian of the Bohemian Cretaceous Basin. It comes from the best-exposed portion of the Peruc-Korycany Formation, in the Pecínov quarry, west of Prague, the Czech Republic. Although preserved only as a fragment of a pinna, it clearly shows haplocheilic stomata. In this paper, we compare N. mirovanae with Pseudoctenis babinensis J.Kvaček from the same horizon. These two cycads have similar adaptations for surviving water stress: thick cuticles and sunken stomata, characteristic features among gymnosperms indicating adaptation to xeromorphic plants, cuticle analysis, Late Cretaceousdrought.

Key words

xeromorphic plants, cuticle analysis, Late Cretaceous

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Preliminary revision of the palynological collection of Professor Blanka Pacltová – a significant collection of Cenomanian microflora housed at the National Museum, Prague

Abstract

A preliminary revision of the palynological collection of Professor Blanka Pacltová was carried out considering samples from the middle Cenomanian of the Peruc-Korycany Formation, the basal most member of the Bohemian Cretaceous Basin (the Czech Republic). This collection is mainly composed of slides with palynological residues for light microscope study, which were mounted in the 1960s and 1970s. This work presents an evaluation of the state of preservation of this collection, taking into account the presence of ancient angiosperm pollen types. High percentage of preparations is affected by degradation of glycerine jelly and their remounting is necessary. The present study additionally suggests a methodology for curation of this collection with the objective of long-term preservation.

Key words

palynological collection, Blanka Pacltová, curation, angiosperm pollen types, early Cenomanian, Bohemian Cretaceous Basin, the Czech Republic

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Marattiopsis vodrazkae sp. nov. (Marattiaceae) from the Campanian of the Hidden Lake Formation, James Ross Island, Antarctica

Abstract

A new fossil eusporangiate fern Marattiopsis vodrazkae J. Kvaček, sp. nov. has been recovered from the Hidden Lake Formation, the Campanian of James Ross Island, Antarctica. Its fertile and sterile pinnules are described and compared to the other species of the fossil genus  Marattiopsis Schimper and the living genera Marattia, Ptisana and Eupodium (Marattiaceae). In contrast to the other species of the genus Marattiopsis, M. vodrazkae is characterised by stalked synangia, a smaller number of sporangia per synangium, generally small sized pinnules, and the absence of venuli recurrentes. It shows a mosaic of characters present in the living Marattiaceae: it shares stalked sporangia with the genus Eupodium and some species of  Marattia and exhibits a suture (an abscission scar at pinnule bases), a character typical for the genus Ptisana. Additionally, M. vodrazkae provides important palaeoenvironmental signals for climate reconstructions, arguing for warm (paratropical to warm-temperate) and humid climatic conditions on the Antarctic Peninsula and adjacent volcanic islands during the Campanian.

Key words

Marattiaceae, Campanian, Cretaceous, James Ross Island, Antarctica

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