Jozsef Palfy
Eötvös Loránd University, Department of Geology, Faculty Member
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In this paper, we present high-resolution early Holocene pollen, plant macrofossil, charcoal, diatom, biogenic silica, and loss-on-ignition records from a mountain lake in the South Carpathians in order to reveal ecosystem response to the... more
In this paper, we present high-resolution early Holocene pollen, plant macrofossil, charcoal, diatom, biogenic silica, and loss-on-ignition records from a mountain lake in the South Carpathians in order to reveal ecosystem response to the 8.2-ka climatic oscillation. We found significant changes both in terrestrial vegetation and lake diatom assemblages in the northern slope of the Retezat Mts between c. 8300 and 8000 cal. yr BP. Rapid changes in relative frequencies and pollen accumulation rates of the major deciduous pollen types associated with peaks in microcharcoal accumulation rates suggested that vegetation disturbance mainly took place in the mixed-deciduous forest zone, where woodland fires partially destroyed the populations of Fraxinus excelsior, Quercus, and Corylus avellana and facilitated the establishment of Carpinus betulus in the forest openings. The diatom record furthermore showed the spread of a planktonic diatom species, Aulacoseira valida, at 8150 cal. yr BP, c...
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ABSTRACT A high resolution stable isotope study of Upper Valanginian-Barremian (Early Cretaceous) belemnites from Bersek Quarry (Gerecse Mountains, Transdanubian Range, Hungary) is presented. Over 190 belemnite rostra (including... more
ABSTRACT A high resolution stable isotope study of Upper Valanginian-Barremian (Early Cretaceous) belemnites from Bersek Quarry (Gerecse Mountains, Transdanubian Range, Hungary) is presented. Over 190 belemnite rostra (including Hibolithes subfusiformis, Duvalia dilatata and Conohibolites gladiiformis) have been analysed for oxygen and carbon isotopes and for trace element geochemistry. The obtained carbon isotope curve shows a long term decrease from similar to 1.2% in the Upper Valanginian to similar to-0.5% in the Upper Hauterivian followed by more variable values in the Early Barremian. Superimposed on this trend are a number of possible shorter term peaks. This pattern broadly follows published carbon isotope curves for the same interval and is therefore thought to reflect a global rather than a regional signal. The oxygen isotopes show the most positive values in the uppermost Valanginian and become increasingly more negative through the Hauterivian into the Barremian. Such changes are interpreted as an increase in marine temperatures through the section. The Mg/Ca data paralleling the oxygen isotope trend confirms our temperature interpretation. The oxygen isotope ratios are generally more negative and therefore allow us to infer warmer temperatures, than those derived from belemnites from time equivalent sections in Germany and Speeton, UK, consistent with the more southerly latitudinal position of the Gerecse Mts. within the Tethys Ocean. The oxygen isotope and Mg/Ca data also reveal habitat differences for the different belemnite groups analysed. Vaunagites pistilliformis, "Belemnites" pistilliformis and Hibolithes typically have more negative oxygen isotope values than Pseudobelus and Duvalia and are therefore interpreted to have lived in warmer and/or shallower parts of the water column, consistent with previous interpretations.
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The 80 km Puchezh-Katunki impact crater is the only one of the six largest known Phanerozoic craters which has not been previously considered as a factor in a biotic extinction event. The age of impact is currently regarded as Ba- jocian... more
The 80 km Puchezh-Katunki impact crater is the only one of the six largest known Phanerozoic craters which has not been previously considered as a factor in a biotic extinction event. The age of impact is currently regarded as Ba- jocian (Middle Jurassic), on the basis of palynostratig raphy of crat er lake sedi- ments, but there is no significant
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The ultimate goal of palaeontological research is to reveal the history of life on Earth. The rise of the discipline of palaeobiology since the 1970s has sometimes been called a 'revolution', given that it places emphasis on the... more
The ultimate goal of palaeontological research is to reveal the history of life on Earth. The rise of the discipline of palaeobiology since the 1970s has sometimes been called a 'revolution', given that it places emphasis on the synoptic analysis of the entire fossil record. Since the new millennium, the Paleobiology Database (PaleoDB) has played a central role in this field of research. Rapid advances in computer technology and the spread of the internet have enabled an international community of palaeontologists to develop a database to hold all the information of the known fossil record. The continuously growing database currently contains approximately 1.2 million records of 300 thousand taxa from 53 thousand references. The data allow statistical treatment to be used in order to correct for known biases of the fossil record, employing subsampling methods for data standardization. Thus an increasingly more reliable view is emerging on: (i) the history of life, (ii) simil...
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ABSTRACT In the last decade, major advances have been made in our understanding of the end-Triassic mass extinction, related environmental changes, and volcanism of the Central Atlantic magmatic province. Studies of various fossil groups... more
ABSTRACT In the last decade, major advances have been made in our understanding of the end-Triassic mass extinction, related environmental changes, and volcanism of the Central Atlantic magmatic province. Studies of various fossil groups and synoptic analyses of global diversity document the extinction and subsequent recovery. The concomitant environmental changes are manifested in a series of carbon isotope excursions (CIE), suggesting perturbations in the global carbon cycle. Besides the earlier-recognized initial and main negative anomalies, a more complex picture is emerging with other CIEs, both negative and positive, prior to and following the Triassic-Jurassic boundary. The source of isotopically light carbon remains debated (methane from hydrate dissociation vs. thermogenic methane), but either process is capable of amplifying an initial warming, resulting in runaway greenhouse conditions. Excess CO2 entering the ocean causes acidification, an effective killing mechanism for heavily calcified marine bio
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Within a ∼60-Myr interval in the Late Triassic to Early Jurassic, a major mass extinction took place at the end of Triassic, and several biotic and environmental events of lesser magnitude have been recognized. Climate warming, ocean... more
Within a ∼60-Myr interval in the Late Triassic to Early Jurassic, a major mass extinction took place at the end of Triassic, and several biotic and environmental events of lesser magnitude have been recognized. Climate warming, ocean acidification, and a biocalcification crisis figure prominently in scenarios for the end-Triassic event and have been also suggested for the early Toarcian. Radiolarians, as the most abundant silica-secreting marine microfossils of the time, provide a control group against marine calcareous taxa in testing selectivity and responses to changing environmental parameters. We analyzed the origination and extinction rates of radiolarians, using data from the Paleobiology Database and employing sampling standardization, the recently developed gap-filler equations and an improved stratigraphic resolution at the substage level. The major end-Triassic event is well-supported by a late Rhaetian peak in extinction rates. Because calcifying and siliceous organisms ...
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ABSTRACT A high resolution stable isotope study of Upper Valanginian-Barremian (Early Cretaceous) belemnites from Bersek Quarry (Gerecse Mountains, Transdanubian Range, Hungary) is presented. Over 190 belemnite rostra (including... more
ABSTRACT A high resolution stable isotope study of Upper Valanginian-Barremian (Early Cretaceous) belemnites from Bersek Quarry (Gerecse Mountains, Transdanubian Range, Hungary) is presented. Over 190 belemnite rostra (including Hibolithes subfusiformis, Duvalia dilatata and Conohibolites gladiiformis) have been analysed for oxygen and carbon isotopes and for trace element geochemistry. The obtained carbon isotope curve shows a long term decrease from similar to 1.2% in the Upper Valanginian to similar to-0.5% in the Upper Hauterivian followed by more variable values in the Early Barremian. Superimposed on this trend are a number of possible shorter term peaks. This pattern broadly follows published carbon isotope curves for the same interval and is therefore thought to reflect a global rather than a regional signal. The oxygen isotopes show the most positive values in the uppermost Valanginian and become increasingly more negative through the Hauterivian into the Barremian. Such changes are interpreted as an increase in marine temperatures through the section. The Mg/Ca data paralleling the oxygen isotope trend confirms our temperature interpretation. The oxygen isotope ratios are generally more negative and therefore allow us to infer warmer temperatures, than those derived from belemnites from time equivalent sections in Germany and Speeton, UK, consistent with the more southerly latitudinal position of the Gerecse Mts. within the Tethys Ocean. The oxygen isotope and Mg/Ca data also reveal habitat differences for the different belemnite groups analysed. Vaunagites pistilliformis, "Belemnites" pistilliformis and Hibolithes typically have more negative oxygen isotope values than Pseudobelus and Duvalia and are therefore interpreted to have lived in warmer and/or shallower parts of the water column, consistent with previous interpretations.
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(please note that the uploaded pdf-version is a proofcopy/preview version, might slightly differ from the published version)
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... Palynological studies of the Triassic/Jurassic boundary with special focus on the extinction event are rare. Fowell and Olsen (1993) described a sudden floral turnover and a notable decrease in pollen and spore diversity coeval with a... more
... Palynological studies of the Triassic/Jurassic boundary with special focus on the extinction event are rare. Fowell and Olsen (1993) described a sudden floral turnover and a notable decrease in pollen and spore diversity coeval with a small iridium anomaly (Olsen et al., 2002 ...
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Middle Hettangian (Early Jurassic) plant macrofossils from the Kamishak Formation at Puale Bay, Alaska occur mainly as leaves and leafy shoots found together with ammonites that allow precise biostratigraphic age assignment. This new... more
Middle Hettangian (Early Jurassic) plant macrofossils from the Kamishak Formation at Puale Bay, Alaska occur mainly as leaves and leafy shoots found together with ammonites that allow precise biostratigraphic age assignment. This new locality is the first in the Jurassic ...
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PÁLFY, J. 2008. The quest for refined calibration of the Jurassic time-scale. Proceedings of the Geologists' Association, 119, 8595. The Jurassic time-scale assigns numerical ages to bound-aries of chronostratigraphic units. A... more
PÁLFY, J. 2008. The quest for refined calibration of the Jurassic time-scale. Proceedings of the Geologists' Association, 119, 8595. The Jurassic time-scale assigns numerical ages to bound-aries of chronostratigraphic units. A well-established ammonite biochronology ...
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Sedimentary and organic facies of a continuous Late Triassic–Early Jurassic toe-of-slope to basin succession of the NE Transdanubian Range (N Hungary) was studied in order to reconstruct the palaeogeographical and eustatic evolution of... more
Sedimentary and organic facies of a continuous Late Triassic–Early Jurassic toe-of-slope to basin succession of the NE Transdanubian Range (N Hungary) was studied in order to reconstruct the palaeogeographical and eustatic evolution of the Csővár Basin, an intraplatform basin of the NW Neotethys margin. Characteristic facies successions point to sea-level changes of different hierarchies. Cyclic patterns, inferred to result from
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Most species of the middle and late Hettangian psiloceratid genusSunrisitesare endemic to the eastern Pacific, where they are common members of ammonoid assemblages. the Taseko Lakes map area in British Columbia yields diverse and... more
Most species of the middle and late Hettangian psiloceratid genusSunrisitesare endemic to the eastern Pacific, where they are common members of ammonoid assemblages. the Taseko Lakes map area in British Columbia yields diverse and well-preservedSunrisitesfaunas which are formally described here for the first time. Three new species are recognized,S. brimblecombei, S. chilcotinensis, andS. senililevis.the new species require an extension of the morphological range of the genus to include forms that become moderately involute at large shell diameters. Signs of sexual dimorphism are apparent within all three new species ofSunrisites.This work extends the stratigraphic range ofSunrisitesto include the latest Hettangian Rursicostatum Zone in North America. The distribution ofSunrisitessuggests that the Hispanic Corridor, which linked the western Tethyan Ocean and the eastern Pacific, may have been open during the Hettangian. Furthermore, occurrences of the genus constrain the Hettangian ...