Zdeněk Vašíček

Taxonomy of Late Jurassic – Early Cretaceous aptychi from Bulgaria

This paper presents the taxonomic revision of Late Jurassic and Early Cretaceous aptychi housed at the National Museum of Natural History, Sofia (Bulgaria). The aptychi came from the pelagic, flysch-like and flysch deposits of Central and North Bulgaria, and most of them have been initially described by StefaNoV (1961). The taxonomic revision has led to the determination of 23 species and subspecies of six genera. A new species named Mortilletilamellaptychus stefanovi is described. The collection contains also the holotype of Didayilamellaptychus filicostatus (StefaNoV), which was previously elevated from a variety to species level by MěchoVa et al. (2010). A valve of Didayilamellaptychus cf. didayi preserved in the body chamber of a Neolissoceras supports the hypothesis that lamellaptychi and perhaps punctaptychi belong to the natural system of ammonites of family Haploceratidae ZIttel, 1884. It became evident that the state of preservation may strongly affect the taxonomic determination of the aptychi. Only in exceptional cases (occurrence of both valves in a pair with different state of preservation) this preservation phenomenon can be revealed and erroneous determination of any of the valves could be possibly avoided.

The northernmost occurrence of the Lower Berriasian ammonite Pseudosubplanites grandis (Štramberk Limestone, Outer Western Carpathians, Czech Republic)

Abstract The first finding of the index ammonite Pseudosubplanites grandis (Mazenot, 1939) in the Lower Berriasian Štramberk Limestone (Outer Western Carpathians, northeastern Czech Republic) is important from the point of view of both the paleogeographical distribution of this species and of more precisely defining the upper boundary of the Štramberk Limestone (Early Berriasian Berriasella jacobi Zone) formerly regarded as Late Tithonian in age. From the taxonomical point of view, new data on a non-deformed cross-section of the adult whorl and above all on the shape of the adult suture line of this species have been obtained.

Some perisphinctoid ammonites of the Stramberk Limestone and their dating with associated microfossils (Tithonian to Lower Berriasian, Outer Western Carpathians, Czech Republic)

Abstract The present contribution deals with the taxonomy of seven species of perisphinctoid ammonite from the Štramberk Limestone (Outer Western Carpathians, Czech Republic) deposited in Moravian-Silesian museums. The age of these studied ammonites is compared with that of index microfossils contained in the matrix adhering to or infilling the studied specimens. The ammonites document a stratigraphic range from earliest Tithonian to early Berriasian. In addition to taxonomy and new ontogenetic data on some species, we also present data on their palaeogeographic distribution. The occurrence of Subboreal himalayitids in the Štramberk Limestone of an early Berriasian age is determined by both the microfauna and accompanying ammonites, which indicate connection of the Silesian-part of the Tethyan Carpathian area with the Subboreal Russian Platform Basin. These records also suggest an early Berriasian age (Jacobi Chron) for the lowermost part of the Ryazanian stage in its type area.

New Tithonian and Lower Berriasian aptychi of Štramberk Limestone from the Kotouč Quarry (Outer Western Carpathians, Czech Republic)

A new collection of aptychi from the Štramberk Limestone in the Kotouč Quarry near Štramberk is presented in this paper as seven species (parataxonomic system) of ribbed calcareous valves. Their stratigraphic position is mostly supported by the occurrence of time-diagnostic ammonites. Four species are new: Beyrichilamellaptychus companyi sp. nov., B. hoedemaekeri sp. nov., B. jansseni sp. nov. and Thorolamellaptychus kleini sp. nov. The mentioned new species as well as B. studeri occur in the Upper Tithonian-Lower Berriasian interval, whereas Punctaptychus punctatus and Beyrichilamellaptychus beyrichi are well known by their wider stratigraphic range: Tithonian-Berriasian.