Bryozoan fauna from the Kunda Stage (Darriwilian, Middle Ordovician) of Estonia and NW Russia

Ernst, Andrej

doi:10.3140/bull.geosci.1843

Cited by 3 publications

(10 citation statements)

References 22 publications

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“…Such accumulations of brown deposits have been reported in different trepostome genera of the Ordovician age (e.g. Corneliussen & Perry 1973; Morrison & Anstey 1979; Ernst & Voigt 2002; Ernst 2022 a ). Those are thought to be remnants of ‘encapsulated’ brown bodies produced during degeneration–regeneration cycles.…”

Section: Discussionsupporting

confidence: 58%

Fossilized soft tissues in Palaeozoic bryozoans

Ernst

2023

Papers in Palaeontology

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Thin sections of three Palaeozoic bryozoans reveal fossilized soft tissues that show the position of organic cuticle and internal structures such as the membranous sac and gut. The fossilization occurred apparently due to fast burial under anoxic conditions. The position of a membranous sac in the Permian trepostome Rhombotrypella superangustata is indicative of a progressive polypide cycle. The position of the polypide in the Ordovician Graptodictya delicata behind the superior and interior hemisepta suggests a protective function of the hemisepta.

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Section: Discussionsupporting

confidence: 58%

Fossilized soft tissues in Palaeozoic bryozoans

Ernst

2023

Papers in Palaeontology

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“…Compared with other bryozoans described from the Baltic basin (Bassler 1911; Koromyslova 2011; Ernst 2022), this 104‐mm‐long by 111‐mm‐wide colony of Prophyllodictya gracilis (Eichwald, 1840) is relatively large and complete (Fig. 2).…”

Section: Methodsmentioning

confidence: 76%

“…Mean lacuna length in this colony (4.26 mm) was longer than that in the congeneric species P . intermedia at 2.7–3.6 mm (Ernst 2022). Mean lacuna width in this species (2.32 mm) was similar to that in P .…”

Section: Discussionmentioning

confidence: 99%

“…4.10) and other ptilodictyid cryptostomes (e.g. Prophyllodictya intermedia in Ernst 2022, fig. 16F).…”

Section: Discussionmentioning

confidence: 99%

“…Herein both terms ‘exilazooecia’ and ‘kenozooecia’ are used for polymorphs that are seemingly identical in structure but are situated in different parts of the colony. In some trepostome taxa, the former could be referred to as ‘exozonal tubes’ (Ernst 2022). The term ‘kenozooecia’ is usually restricted to polymorphs in modern cheilostomes and cyclostomes that are developed in stereom that lack autozooecia and which fulfil a strengthening purpose among others (Taylor 2020, p. 72).…”

Section: Methodsmentioning

confidence: 99%

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Astogenetic morphological variation in the bryozoan Prophyllodictya gracilis from the Middle Ordovician of Russia and inferred colony‐wide feeding currents

Key

Jackson

McDowell

et al. 2023

Papers in Palaeontology

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The discovery of a relatively large and complete ptilodictyid bryozoan colony enabled morphometric analysis of astogenetic change from the colony base to the periphery. This enabled us to test the hypothesis that the relative area of feeding and non-feeding zooids must be relatively constant across astogenetic growth in this colony. The colony is a stenolaemate cryptostome belonging to the cribrate species Prophyllodictya gracilis (Eichwald). It was recovered from the Volkhov Formation (Dapingian Stage of the Middle Ordovician) from the Putilovo Quarry east of St Petersburg, Russia. The colony was digitally imaged so lacuna and branch dimensions could be measured relative to the colony base and colony edge. Branch thickness and width decreased from the colony base to the top of the colony. Lacuna area and the number of autozooecial rows per branch also decreased distally while the number of lacunae per area increased. As a result, there was an astogenetically stable ratio of autozooidbearing skeletal branch area to the total lacuna area across the colony. This characteristic is interpreted as a requirement of colony-wide feeding currents in this cribrate cryptostome colony.

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Morphological features of Late Ordovician (Sandbian) bryozoans from the basin of Khrevitsa River (north-western Russia) and description of a new species of the genus Prophyllodictya Gorjunova, 1987

Tolokonnikova

Fedorov

2023

Zootaxa

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Some Sandbian (Late Ordovician) bryozoans are here described from the Leningrad region, north-western Russia. The studied association is represented by eight species including one new cryptostome bryozoan Prophyllodictya khrevitsa n. sp. We explore the colony morphology and evolutionary morphogenesis of Prophyllodictya Gorjunova, 1987 and discuss the morphological features of trepostome and cryptostome bryozoans from the Khrevitsa Formation. Finally, we classify protective structures in bryozoan colonies in three groups based on functional criteria: 1) structures to strengthen the colony, 2) structures to defend the colony against predators, and 3) structures to protect the polypide.

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Bryozoan fauna from the Kunda Stage (Darriwilian, Middle Ordovician) of Estonia and NW Russia

Cited by 3 publications

References 22 publications

Fossilized soft tissues in Palaeozoic bryozoans

Fossilized soft tissues in Palaeozoic bryozoans

Astogenetic morphological variation in the bryozoan Prophyllodictya gracilis from the Middle Ordovician of Russia and inferred colony‐wide feeding currents

Morphological features of Late Ordovician (Sandbian) bryozoans from the basin of Khrevitsa River (north-western Russia) and description of a new species of the genus Prophyllodictya Gorjunova, 1987

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