Cephalonega

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Extinct genus of invertebrates

title: "Cephalonega" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["enigmatic-proarticulata-taxa", "fossil-taxa-described-in-1976", "fossils-of-russia", "white-sea-fossils", "ediacaran-life", "controversial-taxa", "monotypic-proarticulatan-genera"] description: "Extinct genus of invertebrates" topic_path: "geography/russia" source: "https://en.wikipedia.org/wiki/Cephalonega" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct genus of invertebrates ::

| name = Cephalonega stepanovi | fossil_range = Ediacaran, around | image = Cephalonega stepanovi life restoration From Ediacaran biota.jpg | image_caption = Reconstruction of Cephalonega stepanovi | parent_authority = Fedonkin in Ivantsov et al., 2019 | taxon = Cephalonega stepanovi | authority = (Fedonkin, 1976) | synonyms = Onega stepanovi Fedonkin, 1976

Cephalonega stepanovi is a fossil organism from Ediacaran deposits of the Arkhangelsk Region, Russia. It was described by Mikhail A. Fedonkin in 1976.{{Cite journal |author1 = B. M. Keller |author2 = M. A. Fedonkin |name-list-style = amp |year = 1976 |script-title = ru:Новые находки окаменелостей в валдайской серии докембрия по р. Сюзьме |trans-title = New Records of Fossils in the Valdaian Group of the Precambrian on the Syuz'ma River |journal = Izv. Akad. Nauk SSSR, Ser. Geol. |volume = 3 |pages = 38–44 |url = http://vend.paleo.ru/pub/Keller_Fedonkin_1976.pdf |language = Russian |url-status=dead |archiveurl = https://web.archive.org/web/20070927022652/http://vend.paleo.ru/pub/Keller_Fedonkin_1976.pdf |archivedate = 2007-09-27

Name

Morphology

::figure[src="https://upload.wikimedia.org/wikipedia/commons/3/3f/Cephalonega_stepanovi.jpg" caption="isomers]] encircled by an undivided zone. The surface of the undivided region of ''Cephalonega'' is covered with small tubercles."] ::

Cephalonega was originally described by Mikhail Fedonkin as a problematic organism, being grouped together with Vendia, Praecambridium and Vendomia as possible stem-group arthropods due to a vague similarity with primitive Cambrian trilobites and arthropods.

In 1985 Mikhail Fedonkin erected Phylum Proarticulata, in which he placed: Cephalonega, Dickinsonia, Palaeoplatoda, Vendia, Vendomia, Praecambridium and Pseudovendia sp., although he did not exclude the possibility that Cephalonega may still be related to various lower Cambrian arthropods, such as Skania.

Andrey Yu. Ivantsov has proposed that Cephalonega should be placed in the phylum Proarticulata, as the segments in recently discovered, exceptionally well-preserved fossils display the glide, or "staggered", symmetry characteristic of the majority of proarticulatans.{{cite journal | author=Ivantsov, A. Yu.

According to a 2019 study, all Cephalonega researchers agree that it is a proarticulatan in the class Cephalozoa that also includes e.g. Yorgia, Andiva and Spriggina.

Fossil record

Imprints of Cephalonega stepanovi have been found in the Verkhovka and Zimnie Gory Formations{{Cite journal | author = D. V. Grazhdankin | year = 2003 | title = The Structure and Sedimentation Conditions in the Vendian assemblage in the Southeastern White Sea | journal = Stratigraphy and Geological Correlation | volume = 11 | issue = 4 | pages = 313–331 | url = http://www.vend.paleo.ru/pub/Grazhdankin%202003.pdf | access-date = 2008-11-04 | archive-url = https://web.archive.org/web/20070804003747/http://www.vend.paleo.ru/pub/Grazhdankin%202003.pdf | archive-date = 2007-08-04 | url-status = dead | author = D. V. Grazhdankin | year = 2004 | title = Patterns of distribution in the Ediacaran biotas: facies versus biogeography and evolution | journal = Paleobiology | volume = 30 | issue = 2 | pages = 203–221 | url = http://www.vend.paleo.ru/pub/Grazhdankin_2004.pdf | doi = 10.1666/0094-8373(2004)0302.0.CO;2 | bibcode = 2004Pbio...30..203G | s2cid = 129376371 | access-date = 2008-11-04 | archive-url = https://web.archive.org/web/20070226031454/http://www.vend.paleo.ru/pub/Grazhdankin_2004.pdf | archive-date = 2007-02-26 | url-status = dead

All the fossil specimens are negative imprints on the bases of fine-grained sandstone beds with the "elephant skin" and tubercle texture diagnostic of microbial mats.{{Cite journal | author = Gehling, J. G. | year = 1999 | title = Microbial mats in terminal Proterozoic siliciclastics: Ediacaran death masks | journal = PALAIOS | volume = 14 | pages = 40–57 | url = http://palaios.geoscienceworld.org/cgi/content/abstract/14/1/40 | doi = 10.2307/3515360 | issue=1 | jstor = 3515360 | bibcode = 1999Palai..14...40G | url-access = subscription The same bedding planes contain various other Ediacaran species: Cyclomedusa, Ediacaria, Palaeopascichnids, Eoporpita, Yorgia, Andiva, Archaeaspinus, Vendia, Dickinsonia, Anfesta, Albumares, Tribrachidium, Kimberella, Parvancorina, Charniodiscus and others.

References

M. A. Fedonkin (1985). "Systematic Description of Vendian Metazoa". ''Vendian System: Historical–Geological and Paleontological Foundation, Vol. 1: Paleontology''. Moscow: Nauka, pp. 70–106.
Stefan Hengtson; Mikhail A. Fedonkin; Jere H. Lipps. (1992). "The Major Biotas of Proterozoic to Early Cambrian Multicellular Organisms". In: Edited by J. William Schopf; Cornelis Klein. ''Proterozoic Biosphere''. Cambridge University Press, pp. 433–435.

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