Protists in the fossil record

Diversity of protists

A protist is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor, the last eukaryotic common ancestor,[1] the exclusion of other eukaryotes means that protists do not form a natural group, or clade.[a] Therefore, some protists may be more closely related to animals, plants, or fungi than they are to other protists. However, like algae, invertebrates and protozoans, the grouping is used for convenience.[2]

Many protists have neither hard parts nor resistant spores, and their fossils are extremely rare or unknown. Examples of such groups include the apicomplexans,[3] most ciliates,[4] some green algae (the Klebsormidiales),[5] choanoflagellates,[6] oomycetes,[7] brown algae,[8] yellow-green algae,[9] Excavata (e.g., euglenids).[10] Some of these have been found preserved in amber (fossilized tree resin) or under unusual conditions (e.g., Paleoleishmania, a kinetoplastid).

Others are relatively common in the fossil record,[11] as the diatoms,[12] golden algae,[13] haptophytes (coccoliths),[14] silicoflagellates, tintinnids (ciliates), dinoflagellates,[15] green algae,[16] red algae,[17] heliozoans, radiolarians,[18] foraminiferans,[19] ebriids and testate amoebae (euglyphids, arcellaceans).[20] Some are used as paleoecological indicators to reconstruct ancient environments.

More probable eukaryote fossils begin to appear at about 1.8 billion years ago, the acritarchs, spherical fossils of likely algal protists.[21] Another possible representative of early fossil eukaryotes are the Gabonionta.

  1. ^ O'Malley, Maureen A.; Leger, Michelle M.; Wideman, Jeremy G.; Ruiz-Trillo, Iñaki (2019-02-18). "Concepts of the last eukaryotic common ancestor". Nature Ecology & Evolution. 3 (3). Springer Science and Business Media LLC: 338–344. doi:10.1038/s41559-019-0796-3. hdl:10261/201794. ISSN 2397-334X. PMID 30778187. S2CID 67790751.
  2. ^ Taylor, F. J. R. 'M. (2003-11-01). "The collapse of the two-kingdom system, the rise of protistology and the founding of the International Society for Evolutionary Protistology (ISEP)". International Journal of Systematic and Evolutionary Microbiology. 53 (6). Microbiology Society: 1707–1714. doi:10.1099/ijs.0.02587-0. ISSN 1466-5026. PMID 14657097.
  3. ^ Introduction to the Apicomplexa. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  4. ^ Fossil Record of the Ciliata. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  5. ^ Klebsormidiales. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  6. ^ Introduction to the Choanoflagellata. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  7. ^ Introduction to the Oomycota. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  8. ^ Introduction to the Phaeophyta Archived 2008-12-21 at the Wayback Machine. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  9. ^ Introduction to the Xanthophyta. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  10. ^ Introduction to the Basal Eukaryotes. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  11. ^ Why Is The Museum On The Web?. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  12. ^ Fossil Record of Diatoms. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  13. ^ Introduction to the Chrysophyta. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  14. ^ Introduction to the Prymnesiophyta. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  15. ^ Fossil Record of the Dinoflagellata. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  16. ^ Systematics of the "Green Algae", Part 1. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  17. ^ Fossil Record of the Rhodophyta. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  18. ^ Fossil Record of the Radiolaria. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  19. ^ Fossil Record of Foraminifera. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  20. ^ Introduction to the Testaceafilosea. Ucmp.berkeley.edu. Retrieved 2014-03-20.
  21. ^ Fossil Record of the Eukaryota. Ucmp.berkeley.edu. Retrieved 2014-03-20.


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