The Ludlow (Late Silurian) neocucullograptid fauna from the southern Tien Shan, Kyrghizstan

Koren, T. N.; Sujarkova, A.A.

doi:10.1080/03115510408619287

Cited by 10 publications

(24 citation statements)

References 16 publications

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“…) and that the range of C. rostratus postdates the saetograptid extinction. Koren' and Sujarkova () recognized a B. tenuis Interzone sandwiched between the S. linearis and Polonograptus podoliensis biozones in Tien Shan, Kyrghizstan, as B. praecornutus and B. cornutus which have their own biozones in the Polish succession made their lowest occurrences as early as in the scanicus‐chimaera and linearis biozones in Tien Shan. In Bohemia, B. praecornutus ranges from the uppermost tenuis Biozone through to the kozlowskii Biozone (Štorch , Manda et al .…”

Section: Graptolite Biozones and Correlationsupporting

confidence: 68%

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The early Ludfordian leintwardinensis graptolite Event and the Gorstian–Ludfordian boundary in Bohemia (Silurian, Czech Republic)

2014

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The late Gorstian to early Ludfordian hemipelagic succession of the south-eastern part of the Prague Synform preserves a rich fossil record dominated by 28 species of planktic graptoloids associated with pelagic myodocopid ostracods, pelagic and nektobenthic orthocerid cephalopods, epibyssate bivalves, nektonic phyllocarids, rare dendroid graptolites, brachiopods, crinoids, trilobites, sponges and macroalgae. Faunal dynamics have been studied with particular reference to graptolites. The early Ludfordian leintwardinensis graptolite extinction Event manifests itself as a stepwise turnover of a moderate diversity graptolite fauna rather than an abrupt destruction of a flourishing biota. The simultaneous extinction of the spinose saetograptids Saetograptus clavulus, Saetograptus leintwardinensis and the rare S. sp. B. at the top of the S. leintwardinensis Zone was preceded by a short-term acme of S. clavulus. Cucullograptus cf. aversus and C. rostratus vanished from the fossil record in the lower part of the Bohemograptus tenuis Biozone. No mass proliferation of Bohemograptus has been observed in the postextinction interval. Limited indigenous speciation gave rise to Pseudomonoclimacis kosoviensis and Pseudomonoclimacis cf. dalejensis. Egregiograptus (the only novel element of cryptic origin) made its earliest occurrence in association with the latest cucullograptids. A postextinction graptolite assemblage of moderate diversity, composed for the most part of long-ranging taxa, persisted through the middle and upper tenuis Biozone until new rediversification in the Neocucullograptus inexpectatus Biozone. Unlike the graptoloids, the planktic, epiplanktic, nektonic and nektobenthic shelly fauna did not suffer significant extinction in the early Ludfordian. The Gorstian-Ludfordian boundary is placed at the lowest occurrence of S. leintwardinensis in spite of the very modest graptolite record available from the Ludfordian GSSP where no graptolites occur below the basal bed of the Lower Leintwardine Formation. Elsewhere, the Gorstian-Ludfordian boundary has been placed at the base of the Saetograptus linearis Biozone which has been considered roughly correlative with the leintwardinensis Biozone. Indeed, our morphometric study places the worldwide biozonal index species S. linearis in synonymy with S. leintwardinensis and thus considerably enhances the biostratigraphical utility of the latter index species. Pseudomonoclimacis antiqua sp. nov. is described.

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Section: Graptolite Biozones and Correlationsupporting

confidence: 68%

“…Correlation of principal G orstian and lower L udfordian graptolite biozonations. Key references used in construction of the chart, in addition to Loydell (): Urbanek and Teller (), Koren' and Sujarkova (, ), Lenz and Kozłowska‐Dawidziuk (), Zalasiewicz et al . (), Manda et al .…”

Section: Graptolite Biozones and Correlationmentioning

confidence: 99%

The early Ludfordian leintwardinensis graptolite Event and the Gorstian–Ludfordian boundary in Bohemia (Silurian, Czech Republic)

2014

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“…This interval is probably coeval with the Bohemograptus bohemicus-Neolobograptus auriculatus biozones erected by Teller (1969) and Urbanek (1970) in the subsurface Silurian rocks of Poland and further updated by Urbanek & Teller (1997). The present B. tenuis Biozone is correlatable also with the B. tenuis Interzone sandwiched between the S. linearis and Polonograptus podoliensis biozones in Tien Shan, Kyrgyzstan (Koren' & Sujarkova, 2004). The present B. tenuis Biozone is correlatable also with the B. tenuis Interzone sandwiched between the S. linearis and Polonograptus podoliensis biozones in Tien Shan, Kyrgyzstan (Koren' & Sujarkova, 2004).…”

Section: A the Bohemograptus Tenuis Biozonementioning

confidence: 64%

“…Two almost circular rhabdosomes encountered from the same level in the Všeradice section exhibit the same parameters medially and distally whereas their proximal parts are broken. f) published a hypothetical complete development of the first theca based on isolated fragments, but subsequently this 'reconstruction' was used as the most essential part in the generic diagnosis of Egregiograptus Rickards & Wright, 1997. Urbanek (1970) erected 'Monograptus' egregius based upon fragmentary material from the kozlowskii Biozone of the Mielnik Borehole in eastern Poland.…”

Section: Systematic Palaeontology (By Petr šTorch)mentioning

confidence: 87%

The graptolite, conodont and sedimentary record through the late Ludlow Kozlowskii Event (Silurian) in the shale-dominated succession of Bohemia

et al. 2011

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The shale-dominated hemipelagic succession exposed in the southwestern part of the Prague Synform preserves the most complete Ludfordian graptolite record so far encountered from peri-Gondwanan Europe. Four graptolite biozones -the Neocucullograptus inexpectatus, Nc. kozlowskii, Pseudomonoclimacis latilobus-Slovinograptus balticus and Pristiograptus fragmentalis biozones -are recognized in the middle and late Ludfordian, between the Bohemograptus tenuis Biozone and the base of the Pridoli Series. Conodont occurrences are restricted to scattered limestone beds, but enable tentative integration of the graptolite and conodont biozonal schemes. Particular attention was paid to faunal and sedimentary changes and the carbon isotope record across the middle Ludfordian Kozlowskii extinction Event. The Kozlowskii Event caused the almost simultaneous extinction of graptolites with ventrally curved rhabdosomes. The genera Bohemograptus, Polonograptus and Neocucullograptus, along with Pseudomonoclimacis dalejensis, disappeared from the fossil record. The offshore conodont fauna recorded in the section was not strongly affected and similarly the pelagic orthocerids and nektonic Ceratiocaris passed unaffected through the extinction interval. The abundant and widespread pelagic myodocopid ostracod Entomis, however, became extinct. The late Ludfordian graptolite recovery gave origin to a novel fauna of Pridoli type from taxa that emerged or just reappeared above the Kozlowskii crisis. In Všeradice and elsewhere in the Prague Synform, the recovery, manifested by the appearance of Pseudomonoclimacis latilobus and Slovinograptus balticus, closely postdates the end of the isotope excursion but pre-dates the first appearance of the conodont index 'Ozarkodina' snajdri. Here the graptolite recovery was delayed relative to the recovery of the benthic fauna. A canalized intraformational limestone conglomerate corresponds with a gap in the sedimentary record above the Kozlowskii extinction and just below the graptolite recovery. The benthic faunas from the conglomerate matrix and pebbles permit correlation with the shallower part of the basin indicating a distinct fall in sea-level. The present data demonstrate the coincidence of the graptolite crisis with benthic faunal change and eustatic fall in sea-level manifested by facies change and the carbon isotope excursion. Polonograptus chlupaci sp. nov., from the Nc. kozlowskii Biozone, is described and several other graptolite taxa are redescribed.

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“…Analogous morphology developed in the thin-walled egregiograptids with an extremely long th 1, confined to the upper Gorstian and lower Ludfordian (Koren' and Sujarkova 2004;Štorch et al 2014), and finally in the lower and middle Ludfordian polonograptids -the third and stratigraphically youngest group distinguished by a short th 1 and much elongated subsequent thecae of a rapidly widening rhabdosome (Koren' and Sujarkova 2004;Manda et al 2012). Polonograptids vanished during the late Ludfordian kozlowskii Extinction Event along with all other ventrally curved monograptids.…”

Section: Discussionmentioning

confidence: 93%

Wenlock–Ludlow boundary interval revisited: new insights from the offshore facies of the Prague Synform, Czech Republic

et al. 2016

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Wenlock–Ludlow boundary beds exposed near Nesvačily in the Prague Synform are documented in terms of their lithology, faunal content, high-resolution record of 19 graptolite species, graptolite biostratigraphy, and conodont record. This is the first time in Bohemia and peri-Gondwanan Europe that a continuous graptolite-bearing section through upper ludensis – middle nilssoni biozones is described in detail to refine high-resolution biostratigraphy and correlation of the Wenlock–Ludlow boundary. Organic-rich shale, relatively rare nongraptolite fauna, and absence of bioturbation indicate a stable deep-water offshore setting with sporadic, low-level bottom oxygenation. The uninterrupted succession revealed a series of origination events of principal graptolite taxa employed in determination of the Wenlock–Ludlow boundary strata worldwide. Bohemograptus represented by B. praecox appeared as early as in the uppermost Wenlock ludensis Biozone. Bohemograptus praecox is later accompanied and replaced by B. bohemicus, associated with Uncinatograptus uncinatus. The lowest Neodiversograptus nilssoni marked the base of the Ludlow nilssoni Biozone. Speciation within Bohemograptus continued in the middle nilssoni Biozone when the robust B. butovicensis evolved from B. bohemicus. Colonograptus colonus shows its lowest occurrence in the middle part of the nilssoni Biozone together with the latest C. gerhardi. The monograptids are associated with abundant and diverse plectograptids that are at present mostly known from Baltica. Bohemograptus praecox sp. nov. and B. butovicensis ( Bouček, 1936 ) are described in the systematic part. The conodont Kockelella ortus absidata, found in the lower–middle part of the nilssoni Biozone, is consistent with a stratigraphic interval within Oz. bohemica and K. crassa conodont biozones.

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The Ludlow (Late Silurian) neocucullograptid fauna from the southern Tien Shan, Kyrghizstan

Cited by 10 publications

References 16 publications

The early Ludfordian leintwardinensis graptolite Event and the Gorstian–Ludfordian boundary in Bohemia (Silurian, Czech Republic)

The early Ludfordian leintwardinensis graptolite Event and the Gorstian–Ludfordian boundary in Bohemia (Silurian, Czech Republic)

The graptolite, conodont and sedimentary record through the late Ludlow Kozlowskii Event (Silurian) in the shale-dominated succession of Bohemia

Wenlock–Ludlow boundary interval revisited: new insights from the offshore facies of the Prague Synform, Czech Republic

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