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Spencer G. Lucas - One of the best experts on this subject based on the ideXlab platform.
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vertebrate Biostratigraphy and biochronology of the upper paleozoic dunkard group pennsylvania west virginia ohio usa
International Journal of Coal Geology, 2013Co-Authors: Spencer G. LucasAbstract:Abstract The Dunkard Group is ~ 343 m of mostly clastic rocks exposed in Pennsylvania, Ohio and West Virginia, USA. Correlation of the Dunkard Group to the Pennsylvanian–Permian boundary has long been debated. Fossil vertebrates from the Dunkard Group include paleoniscoids, dipnoans, a rhipidistian crossopterygian, selachians, lepospondyl and temnospondyl amphibians, diadectomorphs, primitive amniotes, eureptiles and eupelycosaurs. These vertebrates represent two biostratigraphically distinct assemblages, one from the Waynesburg and Washington formations and the other from the overlying Greene Formation. Comparison of the Dunkard vertebrate Biostratigraphy to a vertebrate Biostratigraphy and biochronology developed in New Mexico–Texas allows correlation to the Coyotean (= latest Virgilian–middle Wolfcampian) and Seymouran (late Wolfcampian–early Leonardian) land-vertebrate faunachrons. Tetrapod taxa from the Waynesburg and Washington formations include Edops and Protorothyris , Coyotean index taxa, as well as the characteristic Coyotean taxa Trimerorhachis , Diadectes , Edaphosaurus and Dimetrodon . Significantly, these Dunkard taxa are best known from the Archer City Formation in Texas, which is late Coyotean (= middle Wolfcampian). The Greene Formation contains the eupelycosaur Ctenospondylus , an index taxon of the Seymouran land-vertebrate faunachron. Dunkard xenacanth selachians support the tetrapod-based correlations. Vertebrate biochronology thus indicates that the Waynesburg and Washington formations are late Coyotean, whereas the Greene Formation is Seymouran. Therefore, vertebrate Biostratigraphy and biochronology indicate that the entire Dunkard Group is Early Permian and likely straddles the Wolfcampian–Leonardian boundary.
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Vertebrate Biostratigraphy and biochronology of the upper Paleozoic Dunkard Group, Pennsylvania–West Virginia–Ohio, USA
International Journal of Coal Geology, 2013Co-Authors: Spencer G. LucasAbstract:Abstract The Dunkard Group is ~ 343 m of mostly clastic rocks exposed in Pennsylvania, Ohio and West Virginia, USA. Correlation of the Dunkard Group to the Pennsylvanian–Permian boundary has long been debated. Fossil vertebrates from the Dunkard Group include paleoniscoids, dipnoans, a rhipidistian crossopterygian, selachians, lepospondyl and temnospondyl amphibians, diadectomorphs, primitive amniotes, eureptiles and eupelycosaurs. These vertebrates represent two biostratigraphically distinct assemblages, one from the Waynesburg and Washington formations and the other from the overlying Greene Formation. Comparison of the Dunkard vertebrate Biostratigraphy to a vertebrate Biostratigraphy and biochronology developed in New Mexico–Texas allows correlation to the Coyotean (= latest Virgilian–middle Wolfcampian) and Seymouran (late Wolfcampian–early Leonardian) land-vertebrate faunachrons. Tetrapod taxa from the Waynesburg and Washington formations include Edops and Protorothyris , Coyotean index taxa, as well as the characteristic Coyotean taxa Trimerorhachis , Diadectes , Edaphosaurus and Dimetrodon . Significantly, these Dunkard taxa are best known from the Archer City Formation in Texas, which is late Coyotean (= middle Wolfcampian). The Greene Formation contains the eupelycosaur Ctenospondylus , an index taxon of the Seymouran land-vertebrate faunachron. Dunkard xenacanth selachians support the tetrapod-based correlations. Vertebrate biochronology thus indicates that the Waynesburg and Washington formations are late Coyotean, whereas the Greene Formation is Seymouran. Therefore, vertebrate Biostratigraphy and biochronology indicate that the entire Dunkard Group is Early Permian and likely straddles the Wolfcampian–Leonardian boundary.
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Triassic ammonoid Biostratigraphy: an overview
Geological Society London Special Publications, 2010Co-Authors: Marco Balini, Spencer G. Lucas, James F. Jenks, Justin A. SpielmannAbstract:Abstract The Triassic chronostratigraphic scale was built on two centuries of research on ammonoid Biostratigraphy and biochronology. Two Triassic stage bases and all of the Triassic substages are currently defined by ammonoid bioevents. The study of Triassic ammonoids began during the late 1700s, and in 1895, Edmund von Mojsisovics, Wilhelm Waagen and Carl Diener published an essentially complete Triassic chronostratigraphic scale based on ammonoid Biostratigraphy. This scale introduced many of the Triassic stage and substage names still used today, and all terminology of stages and substages subsequently introduced has been based on ammonoid Biostratigraphy. Early Triassic ammonoids show a trend from cosmopolitanism (Induan) to latitudinal differentiation (Olenekian), and the four Lower Triassic substage (Griesbachian, Dinerian, Smithian and Spathian) boundaries are globally correlated by widespread ammonoid biotic events. Middle Triassic ammonoids have provinciality similar to that of the Olenekian and provide a basis for recognizing six Middle Triassic substages. Late Triassic ammonoids provide a basis for recognizing three stages divided into five substages. The main uncertainty for the future of Triassic ammonoid Biostratigraphy is not the decline of the ammonoids as a tool for dating and correlation of Triassic strata but, rather, the dramatic decrease in the number of specialists, due to the lack of replacement of experienced palaeontologists who started their activity in the 1950s and 1960s.
Justin A. Spielmann - One of the best experts on this subject based on the ideXlab platform.
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Triassic ammonoid Biostratigraphy: an overview
Geological Society London Special Publications, 2010Co-Authors: Marco Balini, Spencer G. Lucas, James F. Jenks, Justin A. SpielmannAbstract:Abstract The Triassic chronostratigraphic scale was built on two centuries of research on ammonoid Biostratigraphy and biochronology. Two Triassic stage bases and all of the Triassic substages are currently defined by ammonoid bioevents. The study of Triassic ammonoids began during the late 1700s, and in 1895, Edmund von Mojsisovics, Wilhelm Waagen and Carl Diener published an essentially complete Triassic chronostratigraphic scale based on ammonoid Biostratigraphy. This scale introduced many of the Triassic stage and substage names still used today, and all terminology of stages and substages subsequently introduced has been based on ammonoid Biostratigraphy. Early Triassic ammonoids show a trend from cosmopolitanism (Induan) to latitudinal differentiation (Olenekian), and the four Lower Triassic substage (Griesbachian, Dinerian, Smithian and Spathian) boundaries are globally correlated by widespread ammonoid biotic events. Middle Triassic ammonoids have provinciality similar to that of the Olenekian and provide a basis for recognizing six Middle Triassic substages. Late Triassic ammonoids provide a basis for recognizing three stages divided into five substages. The main uncertainty for the future of Triassic ammonoid Biostratigraphy is not the decline of the ammonoids as a tool for dating and correlation of Triassic strata but, rather, the dramatic decrease in the number of specialists, due to the lack of replacement of experienced palaeontologists who started their activity in the 1950s and 1960s.
Marco Balini - One of the best experts on this subject based on the ideXlab platform.
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Biostratigraphy of Triassic Ammonoids
Topics in Geobiology, 2015Co-Authors: James F. Jenks, Marco Balini, Claude Monnet, Arnaud Brayard, Maximiliano MeierAbstract:The Triassic is a turning point in the evolutionary history of ammonoids, characterized by the flourishing Ceratitida and the appearance of the first heteromorphs. Following the end-Permian mass extinction, ammonoids were among the first groups to rediversify by producing many new taxa. Already in the late nineteenth century, the still currently recognized Triassic stages and substages were introduced. The historical development of Triassic ammonoid Biostratigraphy is a good example of worldwide cooperation between many geographically-diverse research groups, which initially began in Germany and the European Alps. This cooperation was then extended to North America, Transcaucasia, North Indian Margin, South China, and Russia. A renewed interest in Triassic ammonoid biozonation has occurred during the last few decades, leading to the recognition of tens of ammonoid zones spanning about 50.9 Myr (leading to an average duration for ammonoid biochronozones of about 0.74 Myr), whose correlation and definition are herein synthesized.
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Triassic ammonoid Biostratigraphy: an overview
Geological Society London Special Publications, 2010Co-Authors: Marco Balini, Spencer G. Lucas, James F. Jenks, Justin A. SpielmannAbstract:Abstract The Triassic chronostratigraphic scale was built on two centuries of research on ammonoid Biostratigraphy and biochronology. Two Triassic stage bases and all of the Triassic substages are currently defined by ammonoid bioevents. The study of Triassic ammonoids began during the late 1700s, and in 1895, Edmund von Mojsisovics, Wilhelm Waagen and Carl Diener published an essentially complete Triassic chronostratigraphic scale based on ammonoid Biostratigraphy. This scale introduced many of the Triassic stage and substage names still used today, and all terminology of stages and substages subsequently introduced has been based on ammonoid Biostratigraphy. Early Triassic ammonoids show a trend from cosmopolitanism (Induan) to latitudinal differentiation (Olenekian), and the four Lower Triassic substage (Griesbachian, Dinerian, Smithian and Spathian) boundaries are globally correlated by widespread ammonoid biotic events. Middle Triassic ammonoids have provinciality similar to that of the Olenekian and provide a basis for recognizing six Middle Triassic substages. Late Triassic ammonoids provide a basis for recognizing three stages divided into five substages. The main uncertainty for the future of Triassic ammonoid Biostratigraphy is not the decline of the ammonoids as a tool for dating and correlation of Triassic strata but, rather, the dramatic decrease in the number of specialists, due to the lack of replacement of experienced palaeontologists who started their activity in the 1950s and 1960s.
Maria Mutti - One of the best experts on this subject based on the ideXlab platform.
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carbon and strontium isotope stratigraphy of the upper cretaceous cenomanian campanian shallow water carbonates of southern italy chronostratigraphic calibration of larger foraminifera Biostratigraphy
Cretaceous Research, 2015Co-Authors: Gianluca Frijia, Matteo Di Lucia, Mariano Parente, Maria MuttiAbstract:Shallow-water carbonates are invaluable archives of past global change. They hold the record of how neritic biologic communities reacted to palaeoenvironmental changes. However, attempts to decipher these geological archives are often severely hampered by the low stratigraphic resolution attained by Biostratigraphy. This is particularly the case for the Upper Cretaceous carbonate platforms of the central Tethyan realm: their Biostratigraphy suffers from very low resolution and poor correlation with the standard biochronologic scales based on ammonites, planktic foraminifers and calcareous nannoplankton. In this paper we show how this problem can be tackled by integrating Biostratigraphy with isotope stratigraphy. We present a detailed record of the benthic foraminiferal Biostratigraphy and carbon and strontium isotope stratigraphy of three upper Cenomanian-middle Campanian sections belonging to the Apennine Carbonate Platform of southern Italy. For the upper Cenomanian-Turonian interval, the carbon isotope curves of the studied sections are easily correlated to the reference curve of the English Chalk. The correlation is facilitated by the matching of the prominent positive excursion corresponding to the Oceanic Anoxic Event 2. For the Coniacian-middle Campanian interval, the correlation is mainly based on strontium isotope stratigraphy. We use the 87Sr/86Sr ratios of the low-Mg calcite of well preserved rudist shells to obtain accurate chronostratigraphic ages for many levels of the three studied sections. The ages obtained by Sr isotope stratigraphy are then used to better constrain the matching of the carbon isotope curves. From the high-resolution chronostratigraphic age-model stablished by isotope stratigraphy, we derive the chronostratigraphic calibration of benthic foraminiferal biostratigraphic events. For the first time the benthic foraminiferal biozones of the Apennine Carbonate Platform can be accurately correlated to the standard ammonite biozonation. This result is of great relevance because the biostratigraphic schemes of other carbonate platforms in the central and southern Tethyan realm are largely based on the same biostratigraphic events.
Leona Koptikova - One of the best experts on this subject based on the ideXlab platform.
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Stratigraphy of the Middle Devonian boundary: Formal definition of the susceptibility magnetostratotype in Germany with comparisons to sections in the Czech Republic, Morocco and Spain
Tectonophysics, 2006Co-Authors: Brooks B. Ellwood, Jenaro Luis García-alcalde, Ahmed El Hassani, Jindrich Hladil, Francisco Soto, Montserrat Truyóls-massoni, Karsten Weddige, Leona KoptikovaAbstract:Abstract One major difficulty in geology is high-resolution correlation among widely separated sections, especially in the Paleozoic where magnetostratigraphy polarity is not well established because rocks are often remagnetized, where critical biostratigraphic zonation may be poor or lacking, or where structural complexities make correlations very difficult. To address this problem, we have been using magnetostratigraphy susceptibility measurements. Here, we report our work from the Middle Devonian in Europe and North Africa. The Middle Devonian (Emsian–Eifelian) global boundary stratotype section and point (GSSP), located in the Eifel Hills, western Germany, was ratified by the International Subcommission on Stratigraphy in 1985, after careful evaluation of the Biostratigraphy for this and many other sections. The boundary interval has been characterized using Biostratigraphy, and the beginning of the Eifelian stage has been specifically defined by the first occurrence of the conodont Polygnathus costatus partitus. We have collected the Eifel Hills section for magnetic susceptibility (MS) measurement and here we establish it as the magnetostratotype for the Emsian–Eifelian stage boundary, by formally defining the magnetostratigraphy susceptibility for the section. We then collected, measured and compared the magnetostratotype to four other sections for which conodont Biostratigraphy has been studied and where P. costatus partitus is present; two Emsian–Eifelian sections in Morocco and two sections in the Czech Republic (including the Emsian–Eifelian parastratotype). Finally, we have measured the MS for the El Puerto Creek section in the Cantabrian Mountains of Spain and identified the location of the Emsian–Eifelian boundary within the section based on MS comparison to the GSSP in conjunction with excellent biostratigraphic indicators, primarily brachiopods. While the conodont zonation in the El Puerto Creek section is poorly defined, we believe that the correspondence between the MS and Biostratigraphy in the section allows the identification of the Emsian–Eifelian boundary. These results indicate that this method can be successfully applied to marine sequences where ambiguities in correlation exist.