AnOistodus venustus-like conodont species from the Middle Ordovician of Baltoscandia

Löfgren, Anita

doi:10.1007/bf02988394

Cited by 9 publications

(4 citation statements)

References 20 publications

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“…The former type, characterized by a low cusp to base ratio, is likely what Viira et al (2001 ) referred to as D. cf D. venustus from the Mäekalda section. Similar elements have also been brought to Venoistodus balticus by Löfgren (2006); however, see Mellgren & Eriksson (2010) for a brief discussion on the ambiguousness concerning this taxon.…”

Section: Sample Interval 1: Est09:oslmentioning

confidence: 91%

Conodont dating of the Middle Ordovician breccia cap-rock limestone on Osmussaar Island, northwestern Estonia

Mellgren¹,

Schmitz²,

Ainsaar³

et al. 2012

Estonian J. Earth Sci.

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Various mechanisms have hitherto been suggested to explain the formation of the Kundan (Middle Ordovician) Osmussaar Breccia in northwestern Estonia. Following the recent discovery of L-chondritic chromite in these peculiar, sand-penetrated strata, it seems plausible that the breccia is impact-related. Herein, the conodont faunas of three thin limestone intervals overlying the breccia at Osmussaar Island have been investigated, with the aim of establishing the age of the event in terms of the Baltoscandian conodont-based biostratigraphical scheme. Based on the presence of Microzarkodina ozarkodella, the limestone directly overlying the breccia is assigned to the M. ozarkodella Subzone of the Lenodus (Eoplacognathus?) pseudoplanus Zone. This is reinforced by means of a faunal shift between this sample interval and the subsequent one, which is directly comparable with a faunal shift in the Mäekalda section, mainland Estonia. The middle, orthoceratite-yielding interval is assigned to the uppermost L. (E.?) pseudoplanus Zone (or, alternatively, the lowermost Eoplacognathus suecicus Zone), whereas the uppermost interval, an oolitic limestone, is referable to the E. foliaceus Subzone, corresponding to the lower part of the Lasnamägi Stage. These results support a connection between the Osmussaar event and the stratigraphic interval yielding abundant meteorites and/or high levels of L-type chromite in Sweden, as they both can be referred to the lower and/or middle part of the Kunda Stage. The minor difference in age between the first limestones deposited after the brecciation and the meteorite and L-chromite-yielding interval in Baltoscandia can be explained as caused by a period of non-deposition, seen as numerous hiatuses of various extent in the Kunda Stage in northwestern Estonia

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Section: Sample Interval 1: Est09:oslmentioning

confidence: 91%

Conodont dating of the Middle Ordovician breccia cap-rock limestone on Osmussaar Island, northwestern Estonia

Mellgren¹,

Schmitz²,

Ainsaar³

et al. 2012

Estonian J. Earth Sci.

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“…Drepanoistodus cf. suberectus , sample LY14-5, #a Drepanoistodus balticus (Löfgren, 2006) DbalL06B 1) and morphological characters/variables. The latter is represented by blue vector lines (see Table 2), the direction and length of which mark the relative importance of the various characters/variables.…”

Section: Fig 24 Dbasr91-lmentioning

confidence: 99%

Middle Ordovician Drepanoistodus (Vertebrata, Conodonta) from Baltica, with description of three new species

Rasmussen

Eriksson

Lindskog

2021

EJT

594

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Drepanoistodus basiovalis (Sergeeva, 1963) is a common conodont species in Middle Ordovician strata of Baltica. For many years it has been widely accepted that the species encompasses a wide range of morphological plasticity. Hence, several different morphotypes that significantly deviate from the holotype have nonetheless been included in the broad species concept. In this study, we performed a detailed taxonomical study on 112 predominantly well-preserved specimens (geniculate elements) from the St. Petersburg region of Russia; 37 of these were selected for morphometric analyses together with 21 well-illustrated specimens from the published literature. The results demonstrate that, among the morphotypes that share some characteristics with D. basiovalis sensu lato, at least five species can be readily distinguished. Hence, three new species – Drepanoistodus iommii sp. nov., D. svendi sp. nov. and D. viirae sp. nov. – are here added to the previously known D. basiovalis and D. contractus (Lindström, 1955). In addition, some specimens were left under open nomenclature and assigned to Drepanoistodus aff. basiovalis and D. cf. suberectus (Branson & Mehl, 1933). In order to objectively compare the Drepanoistodus taxa and test the validity of the new species, we performed a Principal Component Analysis combined with non-parametric (PERMANOVA) tests based on 21 morphological characters.

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“…In the Hengdu section, the associated conodont fauna includes Costiconus costatus (Rasmussen, ; Figure N–Q), Coelocerodus trigonius Ethington, , Decoriconus sp. (Figure Y and Z), Drepanodus arcuatus Pander, (Figure AA–AD), Drepanodus reclinatus (Lindström, ; Figure AE–AG), Drepanoistodus basiovalis (Sergeeva, ; Figure AH and AI), D. tablepointensis (Stouge, ; Figure A–F), H. holodentata Ethington & Clark, (Figure G–I), Minimodus maocaopus (J. H. Zhang, ; Figure P–T), Paroistodus horridus (Barnes & Poplawski, ; Figure L and M), Periodon macrodentatus (Graves & Ellison, ; Figure G–N), Protopanderodus calceatus Bagnoli & Stouge, (Figure AB–AD), P rotopanderodus cooperi (Sweet & Bergström, ; Figure AE–AG), Spinodus spinatus (Hadding, ; Figure N and O), and Venoistodus balticus Löfgren, .…”

Section: Conodont Biostratigraphy and Correlationmentioning

confidence: 99%

“…Drepanoistodus basiovalis (Sergeeva, 1963; Figure 3AH and AI), D. tablepointensis (Stouge, 1984; Figure Figure 4AB-AD), Protopanderodus cooperi (Sweet & Bergström, 1962; Figure 4AE-AG), Spinodus spinatus (Hadding, 1913; Figure 4N and O), and Venoistodus balticus Löfgren, 2006.…”

Section: Dzikodus Tablepointensis Biozonementioning

confidence: 99%

Biostratigraphy and palaeoecology of Middle and Late Ordovician conodonts from the Hulo and Yenwashan formations, western Zhejiang, south‐eastern China

Stouge

Zhang

et al. 2019

Geological Journal

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A total of 5,918 conodonts have been recovered from the upper Hulo Formation and the lower Yenwashan Formation in the Hengdu section, Jiangshan County, Zhejiang Province, south‐eastern China, spanning the interval from the middle Darriwilian to the early Sandbian. Thirty‐three species, belonging to 24 genera, have been identified with three biozones (i.e., the Dzikodus tablepointensis Biozone, the Histiodella kristinae Biozone, and the Pygodus anserinus Biozone) recognized in the region. Using multivariate analysis, the Periodon–Protopanderodus biofacies is recorded from the upper Hulo Formation, and the Periodon–Pygodus biofacies and the Protopanderodus–Baltoniodus biofacies are recorded from the lower Yenwashan Formation. The Periodon–Protopanderodus biofacies and the Periodon–Pygodus biofacies represent a deep‐water environment, such as the margin of the platform and/or slope environment, deeper than that of the Protopanderodus–Baltoniodus biofacies.

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AnOistodus venustus-like conodont species from the Middle Ordovician of Baltoscandia

Cited by 9 publications

References 20 publications

Conodont dating of the Middle Ordovician breccia cap-rock limestone on Osmussaar Island, northwestern Estonia

Conodont dating of the Middle Ordovician breccia cap-rock limestone on Osmussaar Island, northwestern Estonia

Middle Ordovician Drepanoistodus (Vertebrata, Conodonta) from Baltica, with description of three new species

Biostratigraphy and palaeoecology of Middle and Late Ordovician conodonts from the Hulo and Yenwashan formations, western Zhejiang, south‐eastern China

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