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  • Author: Jiří Kvaček x
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Abstract

An anatomically preserved fossil fruit Allericarpus parvivalvis (Bayer) J. Kvaček et Heřmanová comb. nov. is described from the Coniacian of Březno (Březno Formation), from the Bohemian Cretaceous Basin. Its morphology is characterised based on x-ray and SEM studies. It shows a pentamerous fruit consisting of loculicidally dehiscent capsules. The fruit is subtended by thin persistent sepals. The taxon is compared to other similar taxa, particularly to two earlier described fossil species of Allericarpus. All its characters indicate relationship with the family Pentaphylacaceae of the order Ericales.

Abstract

Several mesofossil floras discovered in the Early Cretaceous rocks from the Lusitanian Basin of western Portugal comprise numerous well-preserved conifer remains. Here we report the occurrence of four conifer types in the mesofossil flora from the Catefi ca locality, about 4 km south of Torres Vedras in the Estremadura region on the western Portuguese Basin. The specimens were recovered from rocks belonging to the Almargem Formation, interpreted to be of late Aptian - early Albian age. It includes three Cheirolepidiaceae genera Frenelopsis SCHENK, Pseudofrenelopsis NATH. and Watsoniocladus V.SRINIV., and one conifer twig of Pagiophyllum-type. These conifers, which co-occurred in the same depositional bed with a well-diversified early angiosperm assemblage including flowers, seeds, fruits and dispersed stamens with pollen in situ, provide new insights into Early Cretaceous palaeoecology.

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.

Abstract

Plant mega- and microfossils are described from the middle Sheinwoodian of the Barrandian area. The material comes from the Loděnice locality and the same horizon as the earliest unequivocal land plant, Cooksonia barrandei LIBERTÍN, J.KVAČEK, BEK, ŽÁRSKÝ et ŠTORCH. Its age (432 Myr) is inferred from the associated graptolite fauna, including the zonal index graptolite Monograptus belophorus. Megafossils have clear similarity with Cooksonia, due to their dichotomised axes with slightly widened subtending axes bearing putative sporangia. They document some of the plant diversity that was in place when the first proven representative of the genus Cooksonia appeared, and together with dispersed spores they provide strong and important evidence that a diversified terrestrial ecosystem had developed on the Barrandian volcanic archipelago in the peri-Gondwanan realm by the end of the Sheinwoodian Stage of the Silurian Period.

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

The Cupressaceae conifer Stutzeliastrobus bohemicus (Bayer) J.Kvaček comb. nov. is described from the Cenomanian Peruc-Korycany Formation of the Bohemian Cretaceous Basin. It is characterised by elongate ovuliferous cones with helically arranged thin, bilaterally symmetrical ovuliferous bract-scale complexes, bearing two to four winged elongate ovoid seeds per bract-scale complex. Ovuliferous cones are found attached to twigs of Cyparissidium-type shoots, showing amphistomatic scale-like leaves with an adaxial cuticle, bearing two stomatal bands with transversely or obliquely orientated monocyclic to amphicyclic stomata. The abaxial cuticle shows monocyclic to amphicyclic stomata scattered irregularly in the basal part of the leaf. The lectotype is compressed, but the 3D preserved lignified specimen, studied using X-ray microtomography, revealed its internal structure. It is compared to Stutzeliastrobus foliatus F.Herrera et al. from the Early Cretaceous of Mongolia, differing in morphology of its bract-scale complexes. The thin ovuliferous cone scales complexes of S. bohemicus bearing two to four winged seeds per cone scale argue for its relationship with Taiwanioideae, the basal subfamily of Cupressaceae.