Editing Microfossil (section)

===Chitinozoa===
[[File:Whole_chitinozoan_cropped.jpg|thumb| A [[Late Silurian]] chitinozoan from the [[Burgsvik beds]] showing its flask shape]]

[[Chitinozoa]] are a [[taxon]] of [[laboratory flask|flask]]-shaped, [[organic matter|organic]] walled [[marine biology|marine]] microfossils produced by an as-yet-unknown organism.<ref name=Mullins>{{cite journal| doi=10.1111/1475-4983.00131| title=A chitinozoan morphological lineage and its importance in Lower Silurian stratigraphy| author= Gary Lee Mullins| year=2000| journal=Palaeontology| volume=43| pages=359–373| issue=2| bibcode=2000Palgy..43..359M| doi-access=free}}</ref>

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.<ref name=Jansonius1978>{{cite book | author = Jansonius, J. |author2=Jenkins, W.A.M.| year = 1978 | chapter = Chitinozoa | isbn = 0-444-00267-7 | title = Introduction to marine micropaleontology. | publisher = Elsevier, New York | pages = 341–357}}</ref> This wide distribution, and their rapid pace of evolution, makes them valuable [[biostratigraphic]] markers.

Their bizarre form has made [[scientific classification|classification]] and ecological reconstruction difficult.  Since their discovery in 1931, suggestions of [[protist]], [[plant]], and [[fungus|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 [[egg (biology)|eggs]] or juvenile stage of a marine animal.<ref name=Gabbott1998>{{cite journal | author = Gabbott, S.E. |author2=Aldridge, R.J. |author3=Theron, J.N. | year = 1998 | title = Chitinozoan chains and cocoons from the Upper Ordovician Soom Shale lagerstatte, South Africa; implications for affinity | journal = Journal of the Geological Society | volume = 155 | issue = 3 | pages = 447–452 | doi = 10.1144/gsjgs.155.3.0447| bibcode = 1998JGSoc.155..447G|s2cid=129236534 }}</ref> However, recent research has suggested that they represent the [[Test (biology)|test]] of a group of protists with uncertain affinities.<ref name=Liang2020>{{Cite journal|last1=Liang|first1=Yan|last2=Hints|first2=Olle|last3=Tang|first3=Peng|last4=Cai|first4=Chenyang|last5=Goldman|first5=Daniel|last6=Nõlvak|first6=Jaak|last7=Tihelka|first7=Erik|last8=Pang|first8=Ke|last9=Bernardo|first9=Joseph|last10=Wang|first10=Wenhui|date=2020-12-01|title=Fossilized reproductive modes reveal a protistan affinity of Chitinozoa|journal=Geology|language=en|volume=48|issue=12|pages=1200–1204|doi=10.1130/G47865.1|bibcode=2020Geo....48.1200L|issn=0091-7613|doi-access=free}}</ref>

The ecology of chitinozoa 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.

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