Chitinozoan

Chitinozoan
Temporal range: 510–358 Ma Cambrian Stage 5 - Famennian (latest Devonian)
Scanning electron micrograph of a late Silurian chitinozoan from the Burgsvik beds, showing its flask-like shape
Scientific classification
Domain:
Eukaryota
Phylum:
incertae sedis
Class:
Chitinozoa

Subgroups

Chitinozoa (singular: chitinozoan, plural: chitinozoans) are a group of flask-shaped, organic walled marine microfossils produced by an as yet unknown organism.[1] Common from the Ordovician to Devonian periods (i.e. the mid-Paleozoic), the millimetre-scale organisms are abundant in almost all types of marine sediment across the globe.[2] This wide distribution, and their rapid pace of evolution, makes them valuable biostratigraphic markers.[3][4]

Their bizarre form has made classification and ecological reconstruction difficult. Since their discovery in 1931, suggestions of protist, plant, and fungal affinities have all been entertained. The organisms have been better understood as improvements in microscopy facilitated the study of their fine structure, and it has been suggested that they represent either the eggs or juvenile stage of a marine animal.[5] However, recent research has alternatively suggested that they represent the test of a group of protists with uncertain affinities.[6]

Chitinozoan ecology is also open to speculation; some may have floated in the water column, where others may have attached themselves to other organisms. Most species were particular about their living conditions, and tend to be most common in specific paleoenvironments. Their abundance also varied with the seasons.

  1. ^ Gary Lee Mullins (2000). "A chitinozoan morphological lineage and its importance in Lower Silurian stratigraphy". Palaeontology. 43 (2): 359–373. Bibcode:2000Palgy..43..359M. doi:10.1111/1475-4983.00131.
  2. ^ Cite error: The named reference Jansonius1978 was invoked but never defined (see the help page).
  3. ^ Jain, Sreepat (2020), Jain, Sreepat (ed.), "Chitinozoa", Fundamentals of Invertebrate Palaeontology: Microfossils, Springer Geology, New Delhi: Springer India, pp. 1–25, doi:10.1007/978-81-322-3962-8_1, ISBN 978-81-322-3962-8, S2CID 241650725
  4. ^ Grahn, Yngve; Pereira, Egberto; Bergamaschi, Sergio (24 August 2010). "Middle and upper Devonian chitinozoan biostratigraphy of the paraná basin in Brazil and Paraguay". Palynology. 26 (1): 135–165. doi:10.1080/01916122.2002.9989570. S2CID 128673881. Retrieved 8 November 2022.
  5. ^ Cite error: The named reference Gabbott1998 was invoked but never defined (see the help page).
  6. ^ Liang, Yan; Hints, Olle; Tang, Peng; Cai, Chenyang; Goldman, Daniel; Nõlvak, Jaak; Tihelka, Erik; Pang, Ke; Bernardo, Joseph; Wang, Wenhui (2020-12-01). "Fossilized reproductive modes reveal a protistan affinity of Chitinozoa". Geology. 48 (12): 1200–1204. Bibcode:2020Geo....48.1200L. doi:10.1130/G47865.1. ISSN 0091-7613.