Tünde Cséfán’s research while affiliated with Eötvös Loránd University and other places

The Albian sediments of the Transdanubian Range in Hungary were deposited in non-marine to fully-marine environments. The studied sections revealed diverse benthic ostracod faunas with moderately-preserved specimens. Forty-six taxa are identified and Cypridea zalanyii n. sp. is newly described. The detailed palaeoecological study of these ostracod faunas provided an opportunity to distinguish eight assemblages. The assemblages include limnic, brackish lagoon, shallow marine, reef and low oxygenated semi-enclosed basin environments in the Northern Tethys region we investigated. This work contributes to the knowledge about Albian non-marine faunas from Europe and explores ecological requirements of brackish faunas.

With the exception of polycopids, Mesozoic myodocopid ostracods are regarded as uncommon in the fossil record. They are known from a few localities in the Tethys, and most of them are considered to be pelagic forms. However, a relatively rich and taxonomically diverse material is derived from Hungarian sections; these represent various formations deposited during the Triassic to Cretaceous.The aim of this study is to summarize the current knowledge of Mesozoic myodocopids and to provide new information concerning their classification and phylogenetic relations. This includes new occurrences of Triassic entomozoid Schallreuterizoe groosae Kozur, 2004, cylindroleberidid Triadocypris sp., cypridinid Palaeocypridina tulceaensis Sebe, 2013, Jurassic thaumatocyprid Pokornyopsis cf. bettenstaedti (Bartenstein, 1949) and P. feifeli (Triebel, 1941). The revision of the holotype of gigantic Triassic Triadogigantocypris balatonica Monostori, 1991 give new results concerning the valve structure and taxonomic position of the genus. Two new genera (Neorichterina n. gen. and Hungaroleberis n. gen.) and four new species (Neorichterina striata n. sp., Pokornyopsis csurgokutensis n. sp., Hungaroleberis retiferus n. sp. and Palaeocypridina goeroegae n. sp.) of the subclass Myodocopa are described. Moreover, most of the Albian to Cenomanian representatives of “Conchoecia” are newly classified as Entomozoidae (Neorichterina n. gen.), which allows to extend the range of the family up to the Cretaceous. A summary of the relevant assemblages present in Hungary will help to complement the existing, previously published literature on myodocopids, and also clarify details about the phylogenetic model of the group.

The benthic ostracod faunas from the Albian succession of the Vértessomló Siltstone in the boreholes Vst-8 and Agt-2 were examined and compared. In the present study 10 species belonging to 8 genera were identified. The aim of the study was to give a picture of the palaeo-environment during the Albian age in this region of the Tethys using the ostracods. The dominance of platycopids in benthic assemblages of both boreholes indicates low-oxygenated bottom water conditions. Moreover, the low diversity, the presence of mainly deeper marine environment favouring podocopid forms and the absence or weakly developed eye spot bearing ostracods indicate a normal marine, shallow bathyal depositional environment. However, differences in the faunal composition of the two boreholes could be observed which can be explained with the different palaeogeographical position of the studied sequences during the Albian.

Occurrences of myodocopid ostracods in fossil record particularly in Mesozoic sequences are very scarce because of preservation potential of their carapaces, despite that Recent forms occur worldwide in various water depths of marine environments as benthic, nektobenthic or planktonic organisms. Two myodocopid ostracod genera ("Conchoecia" and Polycope) belonging to two families Halocyprididae and Polycopidae were identified from the studied Lower to Middle Albian successions of the boreholes Agt-2 and Vst-8. These occurrences from Vertes Foreland of Hungary are one of the earliest representatives of halocyprid ostracods. These data completed the palaeobiogeographical distribution of the described genera during the Albian in the Tethys Ocean. The previous paleoenvironmental reconstructions based on planktonic and benthic foraminifera faunas in the studied boreholes confirmed the same ecological requirement of Cretaceous halocyprid forms as that of their living relatives. The depositional environment of Vértessomló Siltstone is shallow bathyal semi-enclosed basin with high organic matter input and dysoxic conditions allowing the preservation of these rare forms.

About 60 years later than the systematic excavation in 1933 carried out by Dr. Mária Mottl and her co-workers, the Vaskapu locality in North Hungary was rediscovered by Dr. János Hír. In the following 15 years, several different field surveys were take place at the site and a rich microvertebrate assemblage were found. The aims of the present study were to review the vertebrate fauna (paying particular attention to the previously poorly studied herpetofauna) and to summarize its taphonomical, biostratigraphical and palaeoecological implications. The slightly mixed assemblage with elements of the forest as well as the grassland habitat is interpreted here as the result of a mosaic or quickly shifting environment left behind a retractive glaciation in the late Würm (namely at the time of the transition between the Pilisszántóian and Palánkian local biochronological stages around 15 000 years ago).