Revision of the Middle–Upper Ordovician acritarch genus Orthosphaeridium Eisenack 1968 nov. emend

Navidi-Izad, Navid; Hashemi, Hossein; Régnier, Sylvie; Kroeck, David M.; Yan, Kui; Servais, Thomas

doi:10.1016/j.revpalbo.2019.104127

Cited by 8 publications

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References 62 publications

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“…It was first described by Eisenack (1968) from the erratic boulders derived from the Ordovician of Baltica and subsequently from many other localities. Orthosphaeridium first appeared in South China in the Expansograptus hirundo graptolite biozone of the early Dapingian (stage slice Dp1 and time slice 3a) and reached a global distribution during the Middle and Late Ordovician (Navidi-Izad et al 2020). In the present material, except for Orthosphaeridium densiverrucosum (Kjellström 1971), which occurred in the samples MG-MHP 215 to MG-MHP 226 of the Lashkarak Formation, the remaining taxa of Orthosphaeridium , including O. ternatum , O. quadrinatum , and O. insculptum , were present in the sample MG-MHP 229 of this formation.…”

Section: Palaeobiogeographymentioning

confidence: 99%

“…nov. (Plate 5, figure 26)Genus Orthosphaeridium Eisenack 1968 emend. Navidi-Izad et al 2020 O. densiverrucosum Kjellström 1971 (Plate 2, figures 3, 7) O. iranense sp. nov. (Plate 4, figures 14–15) O. insculptum Loeblich 1970 (Plate 4, figures 1–6) O. quadrinatum (Burmann 1970) Eisenack et al 1976 (Plate 2, figures 4, 8) O. ternatum (Burmann 1970) Eisenack et al 1976 (Plate 2, figures 2, 6) O. cf.…”

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Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

Ghavidel‐Syooki

Piri-Kangarshahi

2023

Palynology

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The Lashkarak Formation (Lower-Middle Ordovician) in the Gerdkuh locality, 10 km west of Damghan city, northern Iran, has been found to contain acritarchs and chitinozoans. This study aimed to understand these chitinozoan and acritarch successions as well as brachiopods in this part of the Alborz Mountains, in a novel manner. Ninety-seven surface samples from this succession were collected and analysed. Thirty samples yielded well-preserved palynomorph taxa such as acritarchs, chitinozoans, and scolecodonts, as well as graptolite remains. In total, 53 taxa were identified among the acritarchs (38 species belonging to 21 genera) and chitinozoans (15 species belonging to 10 genera). Although scolecodonts and graptolite remains were also observed, they were not studied in detail. The palynological analyses revealed the presence of several diagnostic acritarchs in the Lashkarak Formation, including Vulcanisphaera simplex, Arbusculidium filamentosum, Coryphidium bohemicum, Dactylofusa velifera, Striatotheca mutua, Arkonia virgata, and Orthosphaeridium ternatum. These acritarchs allowed the recognition of five acritarch assemblage zones. Similarly, seven chitinozoan biozones were recognised: Eremochitina brevis, Desmochitina ornensis, Belonechitina henryi, Cyathochitina protocalix, Cyathochitina calix, Siphonochitina formosa, and Laufeldochitina clavata. These findings confirm the inclusion of the Alborz Mountains in the peri-Gondwana palaeoprovince during the Early-Middle Ordovician. The co-occurrence of the acritarch and chitinozoan taxa with previously identified brachiopods allowed for the establishment of a more detailed Early-Middle Ordovician biozonation, demonstrating their potential usefulness for global chronostratigraphy. Based on palynological and brachiopod assemblages, a shallow marine inner shelf setting is suggested for the Early-Middle Ordovician at the Gerdkuh locality. Moreover, in this study, four new morphotype species were erected, consisting of one new chitinozoan (Cyathochitina gerdkuhensis sp. nov.) and three new acritarchs (Baltisphaeridium razii sp. nov., Navifusa alborzensis sp. nov., and Orthosphaeridium iranense sp. nov.). However, Othosphaeridium cf. ternatum was left in open nomenclature. HIGHLIGHTSPalynomorphs from the Lower-Middle Ordovician (Lashkarak Formation) were recorded from the Alborz Mountains. 15 chitinozoan species (10 genera) were recorded from the Lashkarak Formation, S. Caspian Sea. 38 acritarch taxa (21 genera) were identified, indicating the N. Gondwanan Domain. The diagnostic acritarch taxa are Arbusculidium, Coryphidium, Striatotheca, and Arkonia. Chitinozoan biozones are E. brevis, D. ornensis, B. henryi, C. protocalix, C. calix, S. formosa, and L. clavata. Baltisphaeridium razii sp. nov., Navifusa alborzensis sp. nov., Cyathochitina gerdkuhensis sp. nov., and Orthosphaeridium iranense sp. nov. is recorded for the first time. A major hiatus corresponds to the Late Ordovician, Silurian, and Early-Middle Devonian.

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Section: Palaeobiogeographymentioning

confidence: 99%

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confidence: 99%

Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

Ghavidel‐Syooki

Piri-Kangarshahi

2023

Palynology

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“…The need for clearer understanding of the structure and variability of key (including Ordovician) taxa and clarification of their stratigraphic ranges and areas of distribution stimulated an increasing number of studies devoted to the revision of the most characteristic genera (Li et al, 2014;Kroeck et al, 2020;Navidi-Izad et al, 2020;Playford et al, 1995;Ribecai and Tongiorgi, 1999;Ribecai et al, 2002;Servais et al, 2007Servais et al, , 2008Wang et al, 2015Wang et al, , 2017Yan et al, 2010Yan et al, , 2017etc.). Whereas previously there was a tendency to describe as many different acritarch morphotypes as possible as independent species or subspecies, the recent detailed taxonomic revisions involving analysis of obvious trends in morphological variability have led to a reduction in the number of species in the composition of genera (and the number of genera, for that matter).…”

Section: Introductionmentioning

confidence: 99%

Acritarch Elektoriskos? williereae (G. & M. Deflandre, 1965) Vanguestaine, 1979 emend. nov. from the Upper Ordovician of the Siberian Platform: New Morphological and Stratigraphic Data

Raevskaya

Dronov

2021

Stratigr. Geol. Correl.

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The morphology of acritarch species Elektoriskos? williereae (G. & M. Deflandre, 1965) Vanguestaine, 1979, previously considered as a Silurian index of the Llandovery, has been clarified, the diagnosis emended, and the stratigraphic distribution expanded. According to new data, the first appearance of E.? williereae was confined to the upper part of the Baksan Horizon near the boundary of the Sandbian and Katian stages of the Upper Ordovician. Co-occurrence of E.? williereae with representatives of the genera Gordonirundum, Nirundella, Peteinosphaeridium, and Sacculidium is a distinct, well-recognizable palynological characteristic of the Katian deposits of the Siberian Platform which can serve for identification, dating, and correlation of the acritarch-bearing strata. Morphological variations in E.? williereae are a stable diagnostic feature of the species that distinguishes it from other taxa. It is possible that the species was sensitive to paleoenvironments and, probably, highly adaptive, which allowed it, remaining almost unchanged, to overcome the global Late Ordovician cooling, which became fatal for many other groups of organisms.

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Biostratigraphy and paleogeography of Middle-Late Ordovician palynomorphs from the Llanos Basin, Colombia

Rubinstein

Vargas

Parra

et al. 2021

Review of Palaeobotany and Palynology

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Revision of the Middle–Upper Ordovician acritarch genus Orthosphaeridium Eisenack 1968 nov. emend

Cited by 8 publications

References 62 publications

Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

Acritarch Elektoriskos? williereae (G. & M. Deflandre, 1965) Vanguestaine, 1979 emend. nov. from the Upper Ordovician of the Siberian Platform: New Morphological and Stratigraphic Data

Biostratigraphy and paleogeography of Middle-Late Ordovician palynomorphs from the Llanos Basin, Colombia

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