Biology:Cephalozoa
Cephalozoa[1] are an extinct class of primitive segmented marine organisms within the Phylum Proarticulata from the Ediacaran period. They possessed bilateral symmetry and were characterized by a thin, rounded body.
Description
Unlike the other classes of proarticulates, the segmentation of the body is not complete and shows a "head" with fine distribution channels. Some species of the Yorgiidae family also show some asymmetry.[2][3][4]
They were discovered in Russia near the White Sea in the Arkhangelsk region, where they lived during the Ediacaran, approximately 635 to 540 Ma (millions of years ago).
Taxonomy
Cephalozoa includes the families Yorgiidae and Sprigginidae, as well as genera not assigned to any family:
Yorgiidae
- † Archaeaspinus Ivantsov, 2007 (synonym of Archaeaspis)
- † Archaeaspinus fedonkini Ivantsov, 2001
- † Yorgia Ivantsov, 1999
- † Yorgia waggoneri Ivantsov, 1999
- † Ivovicia Ivantsov, 2007
- † Ivovicia rugulosa Ivantsov, 2007
Sprigginidae
- † Spriggina Glaessner, 1958
- † Spriggina floundersi Glaessner, 1958
- † Spriggina ovata Glaessner and Wade, 1966 now considered synonym of Marywadea ovata.
- † Marywadea Glaessner, 1976
- † Marywadea ovata Glaessner and Wade, 1966
- † Cyanorus Ivantsov, 2004
- † Cyanorus singularis Ivantsov, 2004
- † Praecambridium Glaessner and Wade, 1966, previously classified as Yorgiidae; now considered a juvenile form of Spriggina[5]
- † Praecambridium sigillum Glaessner and Wade, 1966
The genera Cephalonega,Andiva, Lossinia and Podolimirus are also included in Cephalozoa, although are not part of any family:[6]
- † Cephalonega Fedonkin in Ivantsov et al., 2019
- † Cephalonega stepanovi Fedonkin, 1976
- † Andiva Fedonkin, 2002
- † Andiva ivantsovi Fedonkin, 2002
- † Lossinia Ivantsov, 2007
- † Lossinia lissetskii Ivantsov, 2007
- † Podolimirus Fedonkin, 1983
- † Podolimirus mirus Fedonkin, 1983
Recent studies indicate that the family Yorgiidae could be included or closely related to the class Vendiamorpha.[7]
See also
References
- ↑ Ivantsov, A. Y. (2001). "Vendia and Other Precambrian "Arthropods"" (in en). Paleontological Journal 35 (4): 335–343. https://www.academia.edu/2605872.
- ↑ Ivantsov, A. Yu (2004). "New Proarticulata from the Vendian of the Arkhangel'sk Region" (in en). Paleontological Journal 38 (3): 247–253. http://vend.paleo.ru/pub/Ivantsov_2004_eng.pdf.
- ↑ Ivantsov, A. Y.; Malakhovskaya, Y. E.; Serezhnikova, E. A. (2004). "Some Problematic Fossils from the Vendian of the Southeastern White Sea Region" (in en). Paleontological Journal 38 (1): 1–9. http://www.vend.paleo.ru/pub/Ivantsov_et_al_2004_eng.pdf. Retrieved 2021-08-11.
- ↑ Ivantsov, A. Y. (2004). Vendian Animals in the Phylum Proarticulata (PDF) (Thesis). Prato, Italy: The Rise and Fall of the Vendian Biota. IGSP Project 493. Abstracts. p. 52.
- ↑ Ivantsov, Andrey Yu (2007). "Small Vendian transversely Articulated fossils" (in en). Paleontological Journal 41 (2): 113–122. doi:10.1134/S0031030107020013. Bibcode: 2007PalJ...41..113I. https://www.academia.edu/2352394.
- ↑ Ivantsov, A. Yu.; Fedonkin, M. A.; Nagovitsyn, A. L.; Zakrevskaya, M. A. (September 2019). "Cephalonega, A New Generic Name, and the System of Vendian Proarticulata". Paleontological Journal 53 (5): 447–454. doi:10.1134/S0031030119050046.
- ↑ Vendiamorpha at fossilworks.org
Template:Proarticulata Wikidata ☰ Q30750018 entry
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