Rostislav Brzobohatý

Diversity and distribution of fossil codlets (Teleostei, Gadiformes, Bregmacerotidae): review and commentary

The Bregmacerotidae is a family of small-sized, pelagic fish within the Gadiformes (i.e. cods) and their fossils are commonly found in Cenozoic marine sediments as articulated skeletons, isolated otoliths or skeletons with otoliths in situ. Although numerous fossils have been published, and their geographical and chronological distributions are well documented, morphological data are often sparse or confusing. Eighteen fossil species of bregmacerotids have been recognised: 17 species within the middle Eocene–Recent genus Bregmaceros (five species based on articulated skeletons, including two with otoliths in situ, and 12 species based on isolated otoliths alone) and the Miocene Bregmacerina antiqua. Here, we provisionally accept the 12 nominal species based on otoliths. However, we find that only two species of Bregmaceros based on body fossils, and both known by otoliths in situ, are diagnosable: B. albyi (including junior subjective synonym B. bosniaski) from the Miocene–Pliocene of Italy, Austria, Greece, Cyprus, Malta and Algeria, and B. filamentosus (including junior subjective synonym B. prahovanus) from the Eocene–Miocene of Egypt, Iran, Czech Republic, Romania, Georgia, Poland and Russia. For the other two species named for body fossils, we regard Bregmaceros carpathicus as a nomen dubium and exclude it from Bregmacerotidae, and we question whether the monospecific Bregmacerina is a bregmacerotid. We provide descriptions of relevant body fossils (including available type specimens), and summarise and discuss the fossil record for the family.

Paleogeography of the Early Badenian connection between the Vienna Basin and the Carpathian Foredeep

The paleogeographic reconstruction for an early Badenian connection of the Vienna Basin and the Carpathian Foredeep in the Mikulov area (Mikulov Gate) based on paleontological (otoliths) and geological (regional geology, tectonics) data has been provided. The ecologically homogenous deep water associations of otoliths in the most NW tip of the Vienna Basin (Sedlec HJ-2 Borehole) links up bathymetrically with nearly adequate otolith assemblages in the southernmost Moravian part of the foredeep. Ten meso- and bathypelagic teleost species have been identified in the Vienna Basin for the first time. Geological analyses proved inversion processes of recurrent nature along old faults of the NW-SE direction in the Dyje (Thaya) Depression. In the early Badenian the Mikulov Gate resulted from the sagging block of the Waschberg Zone. This marine channel was relatively deep (> 200m, as indicated by otoliths) and in all probability flooded an entire front of the nappes in this area.

The Badenian parastratotype at Židlochovice from the perspective of the multiproxy study

Two shallow boreholes were drilled in 2010 into the Badenian (Langhian) parastratotype at Zidlochovice (Carpathian Foredeep, NN5 Zone, Czech Republic). Their profiles (26 m of sediment) were studied comprehensively (sedimentology, palaeontology-calcareous nannoplankton, red algae, palynology, Foraminifera, Bryozoa, Brachiopoda, Ostracoda, Mollusca, Teleostei and Elasmobranchii). The sedimentary succesion was biostratigraphically correlated with the NN5 Zone (14.9-13.9 Ma), namely with the initial time of the Middle Miocene Climatic Transition. Seven lithofacies representing multiple alternations of mudstone, sandstone and limestone facies were recognised within sedimentary succession. Fossils indicated a normal marine, warm to subtropical environment. The generally shallowing trend from the bottom (epibathyal/circalittoral) to the top (shallow infralittoral) of the sedimentary succession with repeated palaeobathymetric changes could be recognized in both boreholes. A mainly subtropical character of terrestrial flora was recorded. Within this framework, either warm wet conditions with seasonal increases, or cooler phases were observed. The abrupt change from mudstone deposited in a calm palaeoenvironment of the upper bathyal/circalittoral to the variegated deposits of shallow water represents the most significant event correlable with the FO of Orbulina (approximately 14.5-14.6 Ma). The interval below the FO of Orbulina can be characterized by mudstone facies and stable conditions of deposition, high nutrient input and a decrease of oxygen content at the bottom. Seasonal stratification of the water column is probable. Within this interval, cooling and an increase of seasonality were recorded. Above the FO of Orbulina, there is evidence of shallowing with a higher flow regime and higher sedimentation rate. The alternation of thick redalgal limestone bodies and variegated sandstone, mudstone and limestone interbeds possibly reflects orbitally forced climatic cyclicity.