Cephalozoa
| Cephalozoa Temporal range: Ediacaran
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| Fossil of Yorgia waggoneri, a cephalozoan found on the shores of the White Sea. | |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | †Cephalozoa Fedonkin, 1985
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| Subtaxa | |
Cephalozoa[1] are an extinct class of primitive segmented marine animals from the Edicarian 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.[3][4][5]
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:
Yorgiidae[]
- † Archaeaspinus Ivantsov, 2007 (synonym of Archaeaspis)
- † Archaeaspinus fedonkini Ivantsov, 2001
- † Yorgia Ivantsov, 1999
- † Yorgia waggoneri Ivantsov, 1999
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[6]
- † Praecambridium sigillum Glaessner and Wade, 1966
The genus Andiva sometimes includes Cephalozoa:
- Andiva , 2002
- Andiva ivantsovi , 2002
Recent studies indicate that the family Yorgiidae could be included or closely related to the class Vendiamorpha.[7]
See also[]
References[]
- ^ a b Ivantsov, A. Y. (2001). "Vendia and Other Precambrian "Arthropods"". Paleontological Journal. pp. 335–343.
- ^ Mikhail A. Fedonkin, James G. Gehling, Kathleen Grey, Guy M. Narbonne, and Patricia Vickers-Rich. Foreword by Arthur C. Clarke. (2008) "The Rise of Animals. Evolution and Diversification of the Kingdom Animalia"
- ^ Ivantsov, A. Yu (2004). "New Proarticulata from the Vendian of the Arkhangel'sk Region" (PDF). Paleontological Journal. pp. 247–253.
- ^ Ivantsov, A. Y.; Malakhovskaya, Y. E.; Serezhnikova, E. A. (2004). "Some Problematic Fossils from the Vendian of the Southeastern White Sea Region" (PDF). Paleontological Journal. pp. 1–9.
- ^ Ivantsov, A. Y. (2004) "Vendian Animals in the Phylum Proarticulata". The Rise and Fall of the Vendian Biota. IGSP Project 493. Abstracts. Prato, Italy, p. 52.
- ^ Ivantsov, Andrey Yu (2007). "Small Vendian transversely Articulated fossils". Paleontological Journal. p. 113. doi:10.1134/S0031030107020013.
- ^ "Fossilworks: Vendiamorpha". fossilworks.org. Retrieved 17 December 2021.
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