Graptolite biostratigraphy of the Lower Silurian (Llandovery and Wenlock) of Bohemia

Štorch, Petr

doi:10.1002/gj.3350290204

Cited by 92 publications

(54 citation statements)

References 18 publications

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“…1), has been dissected by major shear-zones: the North Armorican Shear Zone (NASZ) and the two branches (North and South) of the South Armorican Shear Zone (SASZ). The NASZ has no palaeogeographical significance as the pre-Carboniferous successions are very similar in the midand north-Armorican regions (Mid-North Armorican Domain of , 1994. The northern branch of the SASZ which separates the Mid-North Armorican Domain and the South Armorican Ligerian Domain (Cogné 1974, Dubreuil et al 1989, Lardeux & Cavet 1994 separates pre-Carboniferous Palaeozoic successions that show important differences , 1994Robardet et al 1994).…”

Section: Geological Settingmentioning

confidence: 99%

Graptolite faunas of the Llandovery “phtanites” at Les Fresnaies (Chalonnes-sur-Loire, southeastern Armorican Massif): Palaeontology and biostratigraphy

Picarra¹,

Robardet²,

Oliveira³

et al. 2009

Bull. Geosci.

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In the SE of the Armorican Massif (France), the Ordovician-Silurian transition and the lower part of the Silurian are exposed at the locality Les Fresnaies at Chalonnes-sur-Loire. The Silurian graptolitic "phtanites" (black cherts) are richly fossiliferous. Detailed sampling allows a description of the graptolite faunas and a precise stratigraphical analysis of the succession that comprises the whole of the Rhuddanian and Aeronian stages. Both the Llandovery graptolite assemblages and the lithologies of Les Fresnaies are similar to those of other lower Silurian successions throughout peri-Gondwanan Europe,

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Section: Geological Settingmentioning

confidence: 99%

Graptolite faunas of the Llandovery “phtanites” at Les Fresnaies (Chalonnes-sur-Loire, southeastern Armorican Massif): Palaeontology and biostratigraphy

Picarra¹,

Robardet²,

Oliveira³

et al. 2009

Bull. Geosci.

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“…Graptoloids were colonial filter-feeding protochordates, generally ranging from a few millimeteres up to ∼200 mm in maximum dimension, which lived suspended in the water column in a range of depth zones. They have been used extensively for correlation and zonation (7)(8)(9)(10), and the stratigraphic distributions of species are well documented. Thus, their observed stratigraphic ranges commonly are inferred to be good approximations of their true ranges in time, and empirical graptoloid range data have been used as examples of, or tests for, macroevolutionary rates (3,4,(11)(12)(13).…”

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confidence: 99%

Greenhouse−icehouse transition in the Late Ordovician marks a step change in extinction regime in the marine plankton

Crampton

Cooper

Sadler

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Two distinct regimes of extinction dynamic are present in the major marine zooplankton group, the graptolites, during the Ordovician and Silurian periods (486−418 Ma). In conditions of "background" extinction, which dominated in the Ordovician, taxonomic evolutionary rates were relatively low and the probability of extinction was highest among newly evolved species ("background extinction mode"). A sharp change in extinction regime in the Late Ordovician marked the onset of repeated severe spikes in the extinction rate curve; evolutionary turnover increased greatly in the Silurian, and the extinction mode changed to include extinction that was independent of species age ("high-extinction mode"). This change coincides with a change in global climate, from greenhouse to icehouse conditions. During the most extreme episode of extinction, the Late Ordovician Mass Extinction, old species were selectively removed ("mass extinction mode"). Our analysis indicates that selective regimes in the Paleozoic ocean plankton switched rapidly (generally in <0.5 My) from one mode to another in response to environmental change, even when restoration of the full ecosystem was much slower (several million years). The patterns observed are not a simple consequence of geographic range effects or of taxonomic changes from Ordovician to Silurian. Our results suggest that the dominant primary controls on extinction throughout the lifespan of this clade were abiotic (environmental), probably mediated by the microphytoplankton.T he importance of the marine plankton in both the carbon cycle and in the food web that supports the diversity of marine life is undisputed. However, the evolutionary dynamics of planktic species and the factors controlling their diversity and evolutionary turnover are still poorly known (1, 2). This is particularly so for the Paleozoic, where problems of preservation and sampling bias, and poor time resolution, have precluded detailed analysis. How does the marine plankton respond to environmental perturbations arising from climate change over geological time? How does background extinction differ from episodic and mass extinction in the pelagic realm? Is the risk of plankton species extinction dependent on the amount of time since the species originated (3)? These questions have important implications for macroevolutionary process, stability of marine ecosystems, and modern biodiversity conservation (3-5). Here, using a new global data set of unparalleled temporal resolution, we attempt to answer these questions.The graptoloid clade (order Graptoloidea) constituted the main component of the early Paleozoic macrozooplankton from the beginning of the Ordovician to the Early Devonian (6). Graptoloids were colonial filter-feeding protochordates, generally ranging from a few millimeteres up to ∼200 mm in maximum dimension, which lived suspended in the water column in a range of depth zones. They have been used extensively for correlation and zonation (7-10), and the stratigraphic distributions of species are well docum...

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“…Depositional set tings, bi otic and en vi ron men tal changes, and stra tig ra phy have been studied in the Lower Si lu rian suc ces sion of the Prague Synform by Bouèek (1953), Køíž (1975Køíž ( , 1992, Štorch and Pašava (1989), Štorch (2006), Štorch and Frýda (2012), Frýda and Štorch (2014) and oth ers. High-res o lu tion cor re la tion of lithological changes re corded in the Lower Si lu rian suc ces sion with en viron men tally driven, world-wide changes is en abled by highly de vel oped graptolite biostratigraphy (Bouèek, 1953;Štorch, 1994, 2006 and car bon iso tope geo chem is try Frýdová, 2014 2016;Frýda and Štorch, 2014;. The geo chem is try of Lower Si lu rian se quences in the Prague Synform was first stud ied by Marešová (1973), fol lowed by Lepka et al (1984).…”

Section: Geological Lithological and Biostratigraphical Descriptionmentioning

confidence: 99%

Trace element variations as a proxy for reconstruction of palaeoenvironmental changes during the Late Aeronian faunal and carbon isotope perturbations: new data from the peri-Gondwanan region

Pašava

Frýda

Štorch

2016

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Trace el e ment vari a tions in the Up per Aeronian (Llandovery, Lower Si lu rian), deep-wa ter, black shale suc ces sion of the Barrandian area (Perunica) were stud ied across an in ter val as so ci ated with a graptolite mass ex tinc tion and global, pos i tive car bon iso tope anom aly. The main aim of the pa per is to test whether dis tinct changes in graptolite di ver sity dur ing Late Aeronian were linked with changes in deep sea wa ter ox y gen a tion. Us ing mul ti ple geo chem i cal prox ies we doc u mented high-fre quency changes in ox y gen a tion of sea wa ter from sed i ments of the convolutus to linnaei (guerichi) biozones. Detailed com par i son of graptolite di ver sity with those high-fre quency ox y gen a tion changes sug gests that the long-term and step-wise Late Aeronian graptolite cri sis was not sig nif i cantly in flu enced by changes in ox y gen level and thus it prob a bly resulted by an other causes. The col lapse of global car bon cy cle dur ing the Late Aeronian prob a bly only tem po rarily in creased ex tinc tion rate of the long-term graptolite cri sis and con sid er ably de creased even ness of the up per most Aeronian graptolite com mu ni ties. The Aeronian graptolite mass ex tinc tion was thus pri mar ily driven by other bi otic and/or abiotic causes.

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Graptolite biostratigraphy of the Lower Silurian (Llandovery and Wenlock) of Bohemia

Cited by 92 publications

References 18 publications

Graptolite faunas of the Llandovery “phtanites” at Les Fresnaies (Chalonnes-sur-Loire, southeastern Armorican Massif): Palaeontology and biostratigraphy

Graptolite faunas of the Llandovery “phtanites” at Les Fresnaies (Chalonnes-sur-Loire, southeastern Armorican Massif): Palaeontology and biostratigraphy

Greenhouse−icehouse transition in the Late Ordovician marks a step change in extinction regime in the marine plankton

Trace element variations as a proxy for reconstruction of palaeoenvironmental changes during the Late Aeronian faunal and carbon isotope perturbations: new data from the peri-Gondwanan region

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