Late Ordovician (Katian) chitinozoans from northwest Saudi Arabia: Biostratigraphic and paleoenvironmental implications

Al-Shawareb, Ahmed; Miller, Merrell A.; Vecoli, Marco

doi:10.1016/j.revmic.2017.08.002

Cited by 10 publications

(14 citation statements)

References 39 publications

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“…The success of the egg hypothesis is mainly owing to the hermetically sealed vesicle which restricts communication between the inner chamber and the outer environment, and the cocoon-like clustered specimens. However, among the 57 recognized chitinozoan genera [48,49], the cocoon-like clusters have only been observed in a single genus— Desmochitina [19,28]. Furthermore, the cocoon-like preservation could also make sense to be interpreted as a reproduction stage, for instance, a multiple fission stage of an individual organism.…”

Section: Discussionmentioning

confidence: 99%

Morphological variation suggests that chitinozoans may be fossils of individual microorganisms rather than metazoan eggs

et al. 2019

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Chitinozoans are organic-walled microfossils widely recorded in Ordovician to Devonian ( ca 485–359 Mya) marine sediments and extensively used in high-resolution biostratigraphy. Their biological affinity remains unknown, but most commonly, they are interpreted as eggs of marine metazoans. Here, we provide new insights into their palaeobiology from three lines of inquiry. We examine morphological variation of a new, well-preserved Late Ordovician species, Hercochitina violana ; analyse a compiled dataset of measurements on 378 species representing all known chitinozoan genera; and compare these data with the size variation of eggs of both extinct and extant aquatic invertebrates. The results indicate that the magnitude of size variation within chitinozoan species is larger than observed in fossil and modern eggs. Additionally, delicate morphological structures of chitinozoans, such as prosome and complex ornamentation, are inconsistent with the egg hypothesis. Distinct and continuous morphological variation in H . violana is more plausibly interpreted as an ontogenetic series of individual microorganisms, rather than as eggs.

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Section: Discussionmentioning

confidence: 99%

Morphological variation suggests that chitinozoans may be fossils of individual microorganisms rather than metazoan eggs

et al. 2019

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“…This interval consists of olive-grey siltstone, fine-grained sandstone, dark shale, and brown impure limestone interbeds, which contain graptolites, identified as Orthograptus amplexicaulis (Ghavidel-Syooki 2001), indicating a Late Ordovician (Katian) age ( clingani to acceps zone), providing additional age control. It has also been recorded from the upper Caradoc (lower Katian) of the Algerian Sahara (Taugourdeau and de Jekhowsky 1960), Morocco (Bourahrouh et al 2004), upper Caradoc (lower Katian), Ra'an Member of the Qasim Formation, Arabian Peninsula (Al-Hajri 1995; Paris et al 2000b; Al-Shawareb et al 2017), upper Caradoc (lower Katian), Turkey (Paris et al 2007), upper Caradoc (lower Katian) of Iran (Ghavidel-Syooki 2001, 2017; Ghavidel-Syooki and Winchester-Seeto 2002; Ghavidel-Syooki and Piri-Kangarshahi 2021) and the Hirnantian, Baq'a Shale Member of the Sarah Formation, Arabian Peninsula (Paris et al 2015). Tanuchitina fistulosa is well-preserved and abundant in the Seyahou Formation (interval samples MG-21 to MG-33), similar to that of the Ra'an Member of the Qasim Formation in the Arabian Peninsula (Paris et al 2000b).…”

Section: Biostratigraphy Of the Chitinozoan Faunasmentioning

confidence: 97%

“…Other chitinozoan taxa in this biozone consist of Calpichitina lenticularis (Bouché 1965), Lagenochitina baltica (Eisenack 1931), Acanthochitina pudica (Vandenbroucke 2008), Pistillachitina pistillifrons (Eisenack 1939), Hyalochitina hyalophrys (Eisenack 1959), Pistillachitina comma (Eisenack 1959), and Rhabdochitina usitata (Jenkins 1967). Amongst these chitinozoan taxa, Rhabdochitina usitata ranges from Middle to Late Ordovician (Darriwilian–Sandbian; see Jenkins 1967), but the others are classical components of the Late Ordovician (late Caradoc) in the North Gondwana Domain (Al-Hajri 1995; Oulebsir and Paris 1995; Ghavidel-Syooki 2001; Ghavidel-Syooki and Winchester-Seeto 2002; Ghavidel-Syooki 2008; Ghavidel-Syooki et al 2011a, 2011b; Paris et al 2015; Ghavidel-Syooki 2016; Al-Shawareb et al 2017; Ghavidel-Syooki 2017; Ghavidel-Syooki and Piri-Kangarshahi 2021).…”

Section: Biostratigraphy Of the Chitinozoan Faunasmentioning

confidence: 99%

Biostratigraphy and palaeogeographic implications of Ordovician and Silurian chitinozoa from the High Zagros Mountains, Northern Persian Gulf, Iran

Ghavidel‐Syooki

2022

Palynology

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A siliciclastic succession is exposed at the Faraghan mountain, northern Persian Gulf, southeastern Iran. A detailed, high-resolution palynological analysis was performed on the Zardkuh, Seyahou, Dargaz, and Sarchahan formations to verify the exact age and palaeogeographic position of the High Zagros Mountains. Two hundred surface samples from this succession were collected and analysed. Most samples yielded abundant and well-preserved chitinozoans, acritarchs, scolecodonts, and cryptospores. Fifty-three chitinozoan species (21 genera) were identified that permitted to establish the

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“…Chitinozoans are organic-walled microfossils common in Ordovician to Devonian marine sediments. In spite of their disputed biological origin (see Liang et al, 2020a and references therein), chitinozoans are widely used in biostratigraphy of early and middle Paleozoic rocks (e.g., Grahn and Gutiérrez, 2001; Asselin et al, 2004; Vandenbroucke, 2004; Grahn, 2005a; Steemans et al, 2009; Vandenbroucke et al, 2010, 2015; de la Puente and Rubinstein, 2013; Wang et al, 2013; Paris et al, 2015a, b; Al-Shawareb et al, 2017; De Weirdt et al, 2019; Liang et al, 2020b) since the regional and global biozonal schemes were first established around the 1990s (Achab, 1989; Paris, 1990; Nõlvak and Grahn, 1993; Verniers et al, 1995; Paris et al, 2004; Grahn, 2005b, 2006). However, alongside revised genus- and family-level systematics (Paris et al, 1999), and continuously expanding datasets from different regions in recent years, revisions of several well-known taxa are required.…”

Section: Introductionmentioning

confidence: 99%

Revision of Ordovician chitinozoan Lagenochitina esthonica sensu lato: morphometrics, biostratigraphy and paleobiogeography

Liang

Nõlvak

et al. 2021

J. Paleontol.

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Lagenochitina esthonica is a globally distributed chitinozoan in Early to Middle Ordovician rocks. It is regarded as an index species for the early Floian in North America and has a stratigraphically constrained range in other regions. Lagenochitina esthonica is distinguished from other chitinozoans by a distinct flexure, a nearly rounded-square chamber, and a cylindrical neck with a flaring collar. However, since the first description of the species in the 1950s, it has included two varieties: a relatively short form with a test length ~400 μm, and a slender form usually longer than 600 μm. In order to revise the taxonomy of the L. esthonica group, we carried out a statistical morphometric study of a large collection of well-preserved specimens from the Baltic region where the taxon was first established. Additionally, the stratigraphic and geographic distribution of both forms was analyzed based on available occurrence data. The results show that the short form occurs in the upper Tremadocian to lower Dapingian, whereas the slender form is mostly reported from the lower and middle Darriwilian. Both forms are identified on Baltica; the short form has also been reported from Laurentia and South China, whereas the other is known also from Avalonia and Gondwana. The morphological distinction, together with differences in stratigraphic and spatial ranges, suggest that the two forms represent separate species: the original stout L. esthonica, based on the morphology of the holotype, and the slender L. megaesthonica n. sp., described herein. The updated taxonomy enhances the stratigraphic and biogeographic usefulness of lagenochitinids globally.UUID: http://zoobank.org/ec49166e-2a8d-4941-8723-f023853c5a7e.

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Late Ordovician (Katian) chitinozoans from northwest Saudi Arabia: Biostratigraphic and paleoenvironmental implications

Cited by 10 publications

References 39 publications

Morphological variation suggests that chitinozoans may be fossils of individual microorganisms rather than metazoan eggs

Morphological variation suggests that chitinozoans may be fossils of individual microorganisms rather than metazoan eggs

Biostratigraphy and palaeogeographic implications of Ordovician and Silurian chitinozoa from the High Zagros Mountains, Northern Persian Gulf, Iran

Revision of Ordovician chitinozoan Lagenochitina esthonica sensu lato: morphometrics, biostratigraphy and paleobiogeography

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