Silurian Spores and Cryptospores From the Arisaig Group, Nova Scotia, Canada

Beck, John H.

doi:10.2113/0250127

Cited by 30 publications

(15 citation statements)

References 44 publications

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“…The dominant members are T. medinensis and L. chibrikovae. During the Katin to the Llandovery, assemblages are dominated by cryptospores, and are very similar with only minor differences reported (Gray 1985;Burgess & Richardson 1991;Richardson 1996;Wellman 1996;Steemans 1999a,b;Steemans et al 2000;Wellman & Gray 2000;Beck & Strother 2001;Steemans & Pereira 2002). In the Late Ordovician and Early Silurian, assemblages of early Rhuddanian are very similar to those from the Ordovician.…”

Section: Sporomorph Assemblage (A) Systematicssupporting

confidence: 80%

“…The second is within the Telychian-Sheinwoodian, Silurian, where there is a minimum value of the sporomorph biodiversity. The low biodiversity of sporomorphs is from the Aeronian to the Sheinwoodian (Steemans 2000;Beck & Strother 2001;Rubinstein & Toro 2006;Richardson & Ausich 2007). Comparison with the biodiversity curves of Steemans (2000) indicates that the biodiversity of the Mojiang assemblage is very similar to that around the Telychian, Llandovery.…”

Section: Sporomorph Assemblage (A) Systematicsmentioning

confidence: 97%

“…The Llandovery sporomorph localities on the palaeogeographical map of the Silurian (minor revision fromChen et al 2001). 1, Pennsylvania, USA(Strother & Traverse 1979;Johnson 1985); 2, New York, USA(Miller & Eames 1982); 3, Virginia, USA(Pratt et al 1978); 4, Ontario, Canada(Eley & Legault 1988); 5, Anticosti Island, Quebec, Canada(Duffield 1985;Richardson & Ausich 2007); 6, Nova Scotia, Canada(Beck & Strother 2001); 7, Wales, UK(Burgess 1991); 8, Ringerike, Norway(Smelror 1987); 9, Belgium (seeSteemans et al 2000); 10, northeast Libya(Richardson 1988); 11, Saudi Arabia(Steemans et al 2000;; 12, Brazil (seeSteemans et al 2000); 13, Paraguay(Gray et al 1992;Steemans & Pereira 2002); 14, northwest Argentina(Rubinstein & Toro 2006); 15, South Africa(Gray et al 1986); 16, Canning Basin, Australia( Foster & Williams 1991); 17, Guizhou, China( Wang et al 1996); 18, Mojiang, China (the present study).…”

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confidence: 99%

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Llandovery sporomorphs and graptolites from the Manbo Formation, the Mojiang County, Yunnan, China

Wang

Zhang

2009

Proc. R. Soc. B.

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Llandovery sporomorphs and graptolites have been recovered from the Manbo Formation, Mojiang area, western Yunnan, China, which belonged to the Indo-China Palaeoplate in the Palaeozoic. The graptolite fauna, including 8 genera and 12 species, is considered Mid Telychian, Llandovery in geological age, confirming the existence of Llandovery rocks in this region. The Silurian stratigraphical sequence of this area is reconsidered as in the ascending order: Manbo Formation (Llandovery-early Wenlock), Shuiqing Formation (late Wenlock-Ludlow) and unnamed formation (Pridoli?). The sporomorph assemblage from the Manbo Formation includes seven species in five genera. The dominant members of this assemblage are Tetrahedraletes medinensis and Laevolancis chibrikovae. Based on the low diversity and low abundance, the geological age of this assemblage is considered to be approximately the Telychian, Llandovery. The parent plants of sporomorphs probably inhabited the landmass near Mojiang area, these sporomorphproducing plants probably included bryophyte-like land plants and primitive vascular land plants. The sporomorph evidence shows that the South China and Indo-China palaeoplates may have been in close proximity (maybe with some continental bridges linking them) to each other at least in the Llandovery. They were also closely related with Gondwanaland in the Llandovery.

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Section: Sporomorph Assemblage (A) Systematicssupporting

confidence: 80%

Section: Sporomorph Assemblage (A) Systematicsmentioning

confidence: 97%

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confidence: 99%

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Llandovery sporomorphs and graptolites from the Manbo Formation, the Mojiang County, Yunnan, China

Wang

Zhang

2009

Proc. R. Soc. B.

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“…, 1974; Gray, 1985; Strother et al. , 1996; Beck & Strother, 2001; Wellman et al. , 2003), although reports of Neoproterozoic terrestrial soil crusts containing photosynthetic organisms (of a cyanobacterial nature?)…”

Section: Introductionmentioning

confidence: 99%

The evolution of the land plant life cycle

2009

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SummaryThe extant land plants are unique among the monophyletic clade of photosynthetic eukaryotes, which consists of the green algae (chlorophytes), the charophycean algae (charophytes), numerous groups of unicellular algae (prasinophytes) and the embryophytes, by possessing, firstly, a sexual life cycle characterized by an alternation between a haploid, gametophytic and a diploid, sporophytic multicellular generation; secondly, the formation of egg cells within multicellular structures called archegonia; and, thirdly, the retention of the zygote and diploid sporophyte embryo within the archegonium. We review the developmental, paleobotanical and molecular evidence indicating that: the embryophytes descended from a charophyte-like ancestor; this common ancestor had a life cycle with only a haploid multicellular generation; and the most ancient (c. 410 Myr old) land plants (e.g. Cooksonia, Rhynia and Zosterophyllum) had a dimorphic life cycle (i.e. their haploid and diploid generations were morphologically different). On the basis of these findings, we suggest that the multicellular reproductive structures of extant charophytes and embryophytes are developmentally homologous, and that those of the embryophytes evolved by virtue of the co-option and re-deployment of ancient algal homeodomain gene networks.

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“…During this time and subsequently cryptospore assemblages from the Middle Ordovician to Early Devonian were documented from around the world: Australia (Foster & Williams 1991); Avalonia (Beck & Strother 2001;Burgess 1991;Burgess & Richardson 1991, 1995Steemans 2001;Wellman 1996); Baltica (Smelror 1987;Hagström 1997;Mehlqvist et al 2012;Vecoli et al 2011); Gondwana (e.g. Breuer & Steemans 2013;Breuer et al 2007, Kermandji 2007Mizusaki et al 2002;Richardson 1988;Rubinstein & Steemans 6 2002; Rubinstein & Vaccari 2004;Spina 2015;Spina & Vecoli 2009;Steemans et al 2000;Strother et al 1996;Tekbali & Wood 1991;Vavrdová 1988;; Laurentia (Beck & Strother 2008;Gray & Boucot 1971;Johnson 1985;Miller & Eames 1982;Pratt et al 1978;Strother & Traverse 1979); Siberia (Raevskaya et al 2016); North China (Wang et al 1997); Peri-Gondwana (Dufka 1995); South China (Wang et al 1996).…”

Section: A Brief History Of Cryptospore Researchmentioning

confidence: 99%

A key for the identification of cryptospores

Steemans

Wellman

2018

Palynology

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Dispersed spores interpreted as deriving from the earliest land plants have complex configurations (e.g. permanent dyads and permanent tetrads) and are readily distinguished from the more familiar trilete spores that often dominate post-late Silurian dispersed spore assemblages. These forms occur mainly from the Middle Ordovician to Early Devonian.They were first recognised in 1971, but it was not until 1979 that the process of formal description commenced. In 1984 they were included in a newly created higher taxonomic grouping called "cryptospores", the term reflecting their complex morphology and then the ongoing debate regarding their affinities. Subsequently the exact definition of the term cryptospore has been debated, with some preferring a wide definition encompassing all non-2 marine palynomorphs produced by algae and early land plants, but others confining inclusion to spores deriving from early embryophytes. Since their recognition, numerous 'cryptospore' taxa have been described. However, their complex morphologies are difficult to interpret and numerous taxonomic debates have confused the delineation of genera and their classification into higher ranks. Here we present a key for the identification of 'cryptospore' taxa with the aim of clarifying some of this confusion.

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Silurian Spores and Cryptospores From the Arisaig Group, Nova Scotia, Canada

Cited by 30 publications

References 44 publications

Llandovery sporomorphs and graptolites from the Manbo Formation, the Mojiang County, Yunnan, China

Llandovery sporomorphs and graptolites from the Manbo Formation, the Mojiang County, Yunnan, China

The evolution of the land plant life cycle

A key for the identification of cryptospores

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