Middle-Upper Ordovician conodonts from the Ffairfach and Golden Grove groups in South Wales, United Kingdom

Ferretti, Annalisa; Bergström, Stig M.

doi:10.1080/08912963.2021.1929952

Cited by 6 publications

(11 citation statements)

References 27 publications

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“…9, figs A, C). While the Pb and S elements of A. inaequalis are similar to those of younger species of Amorphognathus (Ferretti & Bergström, 2022), the M element can be differentiated mainly by lack of a prominent posteriorly directed denticle, which is characteristic of the M element of A. tvaerensis . However, the illustrated M elements of A. inaequalis are broken (Bergström et al 1987, pl.…”

Section: Systematic Descriptionmentioning

confidence: 87%

“…18.1, fig. 8; Ferretti & Bergström, 2022, pl. 9, figs A, B) have an extra postero-lateral process on the outer side as is known in the dextral Pa elements of the younger species, A. tvaerensis.…”

Section: Systematic Descriptionmentioning

confidence: 99%

“…9, figs A, B) have an extra postero-lateral process on the outer side as is known in the dextral Pa elements of the younger species, A. tvaerensis. Additionally, both Pa elements of A. tvaerensis have a slight curvature on the posterior process (Ferretti & Bergström, 2022, pl. 11, figs B, C), while no recognizable curvature is recognized in A. inaequalis (Ferretti & Bergström, 2022, pl.…”

Section: Systematic Descriptionmentioning

confidence: 99%

“…Additionally, both Pa elements of A. tvaerensis have a slight curvature on the posterior process (Ferretti & Bergström, 2022, pl. 11, figs B, C), while no recognizable curvature is recognized in A. inaequalis (Ferretti & Bergström, 2022, pl. 9, figs A, C).…”

Section: Systematic Descriptionmentioning

confidence: 99%

“…18.1, fig. 10; Ferretti & Bergström, 2022, fig. 9J, K) or shown in lateral view only (Lindström et al 1974, pl.…”

Section: Systematic Descriptionmentioning

confidence: 99%

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Emended Sandbian (Ordovician) conodont biostratigraphy in Baltoscandia and a new species ofAmorphognathus

2022

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Conodonts are an important biostratigraphic tool for many Phanerozoic stages. Along with graptolites, they define all global Ordovician Stage boundaries. Within the Upper Ordovician interval, a known species of Amorphognathus tvaerensis (Bergström) is present in both Sandbian and Katian stratotype sections. Study of changes in the succession of A. tvaerensis revealed that elements in the upper part of its range differ morphologically quite distinctly from those in its lower part. Here, they are described as a new conodont species, A. viirae sp. nov. This new species is recognized in several Estonian and Swedish sections, with apparent occurrence also in Mójcza Quarry, Holy Cross Mountains, Poland and Black Knob Ridge, Oklahoma, USA. Detailed analysis of early Amorphognathus elements from Estonian and Swedish sections revealed the absence of A. inaequalis (Rhodes) in both regions, although a conodont subzone based on this species was identified earlier by some authors. Both the absence of A. inaequalis (Rhodes) and recognition of the new species A. viirae sp. nov. resulted in the revision of the conodont zonation, and a new version of it is proposed for the Sandbian Stage in the Atlantic Realm. The new zonation includes (from below) Pygodus anserinus, Baltoniodus variabilis, A. tvaerensis, B. gerdae, A. viirae and B. alobatus Conodont zones.

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Section: Systematic Descriptionmentioning

confidence: 87%

Section: Systematic Descriptionmentioning

confidence: 99%