Colonial palynomorphs from the Upper Ordovician of north-eastern Iran: ‘thalli’, coenobial Chlorophyceae (Hydrodictyaceae) or cyanobacteria?

Navidi-Izad, Navid; Hashemi, Hossein; Cascales‐Miñana, Borja; Régnier, Sylvie; Wellman, Charles H.; Servais, Thomas

doi:10.1080/01916122.2019.1657197

Cited by 10 publications

(8 citation statements)

References 53 publications

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“…The only exceptions to this condition are the planar cellular clusters of relative isodiametric cells, such as those illustrated in Figure 4f and 4g. Similar cellular sheets are known from Ordovician non-marine deposits (Navidi-Izad et al 2019), so this may represent a persistent vegetative morphotype, probably belonging to freshwater, planktonic chlorophytes.…”

Section: State Of Biological/evolutionary Complexity Of Early Eukaryotessupporting

confidence: 56%

The Nonesuch Formation Lagerstätte: a rare window into freshwater life one billion years ago

Strother

Wellman

2020

JGS

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The Nonesuch Fm most likely represents an ancient lake that formed between 1083-1070 Ma. Exceptional preservation, seen in palynological preparations, provides a snapshot of cell morphology, biological complexity and ecology at an early stage in the evolution of the eukaryotes. A wide range of unicellular organization is documented in both vegetative and encysted cell morphologies, but the extent to which multicellularity is developed seems very limited at this time. Overall, the Nonesuch microbiota, when viewed as a Lagerstätte, opens up a window onto the early evolution of unicellular eukaryotes, presenting an essential baseline of both eukaryotic diversity and cell structure well in advance of eukaryotic diversification documented in marine deposits from the later Neoproterozoic.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5183652

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Section: State Of Biological/evolutionary Complexity Of Early Eukaryotessupporting

confidence: 56%

The Nonesuch Formation Lagerstätte: a rare window into freshwater life one billion years ago

Strother

Wellman

2020

JGS

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“…Also clearly distinct are coenobial forms such as Deflandastrum Combaz 1962, Ericanthea Cramer & Díez de Cramer 1977, Kahfia Le Hérissé et al 1995, Proteolobus Wood 1997 and Speculaforma Miller et al 2017. Usually, well-organised Palaeozoic forms consisting of simple spheres (such as Grododowon orthogonalis Strother et al 2017) have been interpreted as colonies of chlorophycean or zygnemaphycean algae or prasinophycean phycomata (see discussion in Navidi-Izad et al 2020). These coenobial forms exhibit a highly organised structure, unlike the other clusters discussed herein.…”

Section: Discussionmentioning

confidence: 99%

“…Henry (1964, fig. 5) Izad et al 2020). These coenobial forms exhibit a highly organised structure, unlike the other clusters discussed herein.…”

Section: Previous Reports Of Acritarch Clustersmentioning

confidence: 99%

Acritarch clusters from the Cambrian (Miaolingian) of the Příbram-Jince Basin, Czech Republic

2022

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Monogeneric clusters of five acritarch genera (Adara, Cymatiosphaera, Eliasum, Synsphaeridium and Timofeevia) were discovered in palynological residues obtained from fine-grained siliciclastic samples from the middle Cambrian (Miaolingian) Jince Formation of the P r ıbram-Jince Basin (Czech Republic). The clusters consist of two to more than 100 individual specimens and lack a common pattern of organisation. Acritarchs within clusters fall within a similar size range, regardless of generic affinity. Proposed mechanisms for the formation of these acritarch clusters are discussed: for the Jince Formation clusters, aggregation within algal blooms or primary colonial behaviour are the most plausible explanations. In addition, a summary of reports of acritarch clusters from lower Palaeozoic strata is included: clusters of a variety of acritarch genera have been documented from rocks of early Cambrian to Late Devonian age.

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“…This species was described by Strother et al (2017) as "Ordovician spore 'thalli'" which may suggest a land plant derived origin. Navidi-Izad et al (2020) discussed the classification of this taxon and of similar colonial palynomorphs. The authors concluded that there is so far no evidence to relate these microfossil colonies to primitive land plants, but possibly to hydrodictyacean algae (Chlorophyceae).…”

Section: Early Land Plant Evidence and The Cryptospore Debatementioning

confidence: 99%

Virgatasporites and Attritasporites: the oldest land plant derived spores, cryptospores or acritarchs?

et al. 2022

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The oldest reported occurrence of cryptospores supposed to derive from land plants (embryophytes) is currently considered to be in the Middle Ordovician. The two genera Virgatasporites and Attritasporites, described in the 1960ʹs from the Early Ordovician (Tremadocian) of Algeria, are morphologically close to the miospores, and therefore pose a dilemma, because these spore-like microfossils are recorded before the first appearance of the oldest land plant derived spores. Here the taxonomy, biostratigraphy and palaeobiogeography of the two genera and their species are revised. Both genera are found in many localities on the Gondwanan border between the late Cambrian and the Middle Ordovician. They have not been found at the margins of other palaeocontinents so far. The biological affinity of the taxa remains uncertain. Several authors considered the two genera to be spore-like microfossils, whereas other authors classified them as acritarchs, i.e. organic-walled microfossils of unknown biological affinity. As the relationship to the embryophyte lineage cannot be established clearly to date, the biological affiliation remains enigmatic. Therefore, in the absence of other evidence, the taxa Virgatasporites and Attritasporites should be temporarily classified as incertae sedis, i.e. as acritarchs, before their true biological affinity is known and they can be adequately placed into a biological group.

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Colonial palynomorphs from the Upper Ordovician of north-eastern Iran: ‘thalli’, coenobial Chlorophyceae (Hydrodictyaceae) or cyanobacteria?

Cited by 10 publications

References 53 publications

The Nonesuch Formation Lagerstätte: a rare window into freshwater life one billion years ago

The Nonesuch Formation Lagerstätte: a rare window into freshwater life one billion years ago

Acritarch clusters from the Cambrian (Miaolingian) of the Příbram-Jince Basin, Czech Republic

Virgatasporites and Attritasporites: the oldest land plant derived spores, cryptospores or acritarchs?

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