Revision of the Cambro-Ordovician acritarch genus Vulcanisphaera Deunff, 1961

Kroeck, David M.; Blanchon, Mathilde; Zacaï, Axelle; Navidi-Izad, Navid; Benachour, Houcine B.; Monnet, Claude; Raevskaya, Elena; Szczepanik, Zbigniew; Servais, Thomas

doi:10.1016/j.revpalbo.2020.104212

Cited by 13 publications

(13 citation statements)

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“…This ordination technique has been widely used in paleontology to help discriminate species based on morphological criteria in groups as varied as sharks (Marramà and Kriwet 2017), killifish (Reichenbacher et al 2007), plants (Álvarez et al 2009), bees (De Meulemeester et al 2012), bryozoans (Cheetham 1986), mollusks (Geary 1992; Marko and Jackson 2001; Reyment 2003), trilobites (Labandeira and Hughes 1994), and brachiopods (Kowalewski et al 1997; Carranza and Carlson 2021). LDA has also been used as a quantitative tool for taxonomic revision of various upper Cambrian and Ordovician acritarch taxa (Wang et al 2017; Yan et al 2017; Kroeck et al 2020).…”

Section: Methodsmentioning

confidence: 99%

Morphometric analysis ofSkiagia-plexus acritarchs from the early Cambrian of North Greenland: toward a meaningful evaluation of phenotypic plasticity

2022

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The Cambrian evolutionary radiations are marked by spectacular biotic turnovers and the establishment of increasingly tiered food chains. At the base of these food chains are primary producers, which in the Cambrian fossil record are chiefly represented among organic-walled microfossils. The majority of these microfossil remains have traditionally been attributed to an informal category of incertae sedis called “acritarchs,” based entirely on form taxonomy. Acritarch form taxa have been intensely used for biostratigraphy and in large-scale studies of phytoplankton diversity. However, both prospects have been challenged by cases of taxonomic inconsistencies and oversplitting arising from the large phenotypic plasticity seen among these microfossils. The acritarch form genus Skiagia stands as an ideal case study to explore these taxonomic challenges, because it encompasses a number of form species widely used in lower Cambrian biostratigraphy. Moreover, subtle morphological differences among Skiagia species were suggested to underlie key evolutionary innovations toward complex reproductive strategies. Here we apply a multivariate morphometric approach to investigate the morphological variation of Skiagia-plexus acritarchs using an assemblage sourced from the Buen Formation (Cambrian Series 2, Stages 3–4) of North Greenland. Our analysis showed that the species-level classification of Skiagia discretizes a continuous spectrum of morphologies. While these findings bring important taxonomic and biostratigraphic hurdles to light, the unequal frequency distribution of life cycle stages among Skiagia species suggests that certain elements of phytoplankton paleobiology are nonetheless captured by Skiagia form taxonomy. These results demonstrate the value of using morphometric tools to explore acritarch phenotypic plasticity and its potential ontogenetic and paleoecological drivers in Cambrian ecosystems.

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Section: Methodsmentioning

confidence: 99%

Morphometric analysis ofSkiagia-plexus acritarchs from the early Cambrian of North Greenland: toward a meaningful evaluation of phenotypic plasticity

2022

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“…Similarly, manifestation of genetically inherent morphological features of acantomorphic acritarchs could have depended on paleoecological factors; also, different taxa could have reacted in different ways. The assumptions repeatedly reflected in the literature (Kroeck et al, 2020;Servais et al, 2004;etc. ) about ecophenotypism of acritarchs comparable to those experimentally proven for dinoflagellates (Dale, 1996;Ellegaard, 2000;Kokinos and Anderson, 1995;Mertens et al, 2009) may be true for E.?…”

Section: Discussionmentioning

confidence: 97%

“…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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“…Recent research not only included the revision of the classification and taxonomy of the acritarchs (e.g. [39]), but also established their precise stratigraphic correlation framework [40]. Regarding palaeobiodiversity, various Palaeozoic acritarch diversity curves have been published [20], and it is shown that there are obvious differences in the diversity curves of different regions or different intervals.…”

Section: Discussionmentioning

confidence: 99%

Palaeoecology of Cambrian–Ordovician acritarchs from China: evidence for a progressive invasion of the marine habitats

Shan

Yan

Zhang

et al. 2022

Phil. Trans. R. Soc. B

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Palaeozoic acritarchs mostly represent organic-walled cysts of marine phytoplankton, and therefore, as primary producers, played an important role in the evolution of marine ecosystems. In this study, we use a selection of the most abundant acritarch taxa from the Cambrian and Ordovician of China to understand the evolution of the palaeoecological patterns of the phytoplankton over the period. The taxa are attributed to 40 easily distinguishable morphotypes, of which the precise palaeoenvironmental distribution from 60 localities is available. By placing the 40 morphotypes on inshore–offshore transects it can be concluded that acritarch microfloras were limited to inshore environments during the early Cambrian, and progressively extended from inshore environments to offshore marine habitats during the later parts of the Cambrian and towards the Early Ordovician, with a prominent shift near the Cambrian–Ordovician boundary, confirming the onset of the ‘Ordovician plankton revolution’. In addition, the acritarch morphotypes evolved from low-diversity assemblages in the early Cambrian, dominated by simple spherical forms with limited ornamentation and simple process structures, to highly diverse assemblages with very complex morphologies in the Early and Middle Ordovician. During the Ordovician, the complex acritarch assemblages occupied most marine habitats, with palaeoecological distribution patterns similar to modern dinoflagellates. This article is part of the theme issue ‘The impact of Chinese palaeontology on evolutionary research’.

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Revision of the Cambro-Ordovician acritarch genus Vulcanisphaera Deunff, 1961

Cited by 13 publications

References 76 publications

Morphometric analysis ofSkiagia-plexus acritarchs from the early Cambrian of North Greenland: toward a meaningful evaluation of phenotypic plasticity

Morphometric analysis ofSkiagia-plexus acritarchs from the early Cambrian of North Greenland: toward a meaningful evaluation of phenotypic plasticity

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

Palaeoecology of Cambrian–Ordovician acritarchs from China: evidence for a progressive invasion of the marine habitats

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