Evolutionary lineages in some Ordovician Chitinozoa

Melchin, Michael J.; Legault, J. A.

doi:10.1080/01916122.1985.9989295

Cited by 20 publications

(12 citation statements)

References 7 publications

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“…only with Hercochitina!} duplicitas and Kalochitina multispinata, but also with Hercochitina lyndsayensis Melchin and Legault, 1985.…”

mentioning

confidence: 95%

Ordovician chitinozoan zonation of Quebec and western Newfoundland

Achab¹

1989

J. Paleontol.

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The purpose of this paper is to propose a chitinozoan zonation of the Ordovician of Quebec and western Newfoundland. On the basis of chitinozoan assemblages previously described from various sections, covering almost the entire Ordovician System, 22 biozones, based on first appearance of index species, are distinguished. As the strata from which the chitinozoan microfaunas were extracted are well dated by other fossils, especially graptolites, it is possible to establish a correlation between the chitinozoan and the established graptolite and conodont zonations of North America and Great Britain.

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“…only with Hercochitina!} duplicitas and Kalochitina multispinata, but also with Hercochitina lyndsayensis Melchin and Legault, 1985.…”

mentioning

confidence: 95%

Ordovician chitinozoan zonation of Quebec and western Newfoundland

Achab¹

1989

J. Paleontol.

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“…The species resembles Hercochitina repsinata (Schallreuter) Melchin & Legault [25] both in vesicle size, outline and similar ornamentation. It differs from Belonechitina repsinata Schallreuter, 1981 [26] in developing a remarkable constriction near the base.…”

Section: Resultsmentioning

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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“…«Number» indicates the number of measured specimens of a species. (Melchin & Legault 1985). Our specimens resemble B. robusta, but they di er from the latter in having rows of aligned spines with connected tops.…”

Section: Belonechitina Hirsutamentioning

confidence: 85%

A chitinozoan biostratigraphy of the Upper Ordovician and lower Silurian strata of the Girvan area, Midland Valley, Scotland

Vandenbroucke¹,

Verniers²,

Clarkson³

2002

Transactions of the Royal Society of Edinburgh: Earth Sciences

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Forty-six samples, taken from the Upper Ordovician and lower Silurian strata of the Girvan district, Midland Valley of Scotland, yield moderately well-preserved and diverse assemblages of chitinozoans. The area was chosen to study the composition of the chitinozoan assemblages, rarely described before in Scotland, which lay at the south-eastern margin of the Laurentia palaeocontinent. These assemblages are compared with those of the same age on other palaeocontinents, representing a critical time when both the Iapetus and Tornquist oceans were closing, thus forming the Caledonide and associated orogens. It is possible to correlate the chitinozoan occurrences at Girvan with those of other parts of Laurentia (Quebec area), other palaeocontinents such as Baltoscandia (Sweden, Estonia), Avalonia (Wales, Brabant Massif) and some parts of Northern Gondwana (Saudi Arabia). For the lower Silurian, it is possible to correlate with the global chitinozoan biozonation, and a calibration between the chitinozoan occurrences and the graptolite biozonation of Girvan is established. Several levels within the Balclatchie, South Shore, Three Mile, Shalloch, Wood Burn, Lauchlan, Drumyork Flags and other formations are accurately dated.

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Evolutionary lineages in some Ordovician Chitinozoa

Cited by 20 publications

References 7 publications

Ordovician chitinozoan zonation of Quebec and western Newfoundland

Ordovician chitinozoan zonation of Quebec and western Newfoundland

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

A chitinozoan biostratigraphy of the Upper Ordovician and lower Silurian strata of the Girvan area, Midland Valley, Scotland

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