Cephalozoa
| Cephalozoa Temporal range: Ediacaran
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|---|---|
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| Fossil of Yorgia waggoneri, a cephalozoan found on the shores of the White Sea. | |
| Scientific classification Edit this classification | |
| Kingdom: | Animalia |
| Phylum: | †Proarticulata |
| Class: | †Cephalozoa Ivantsov, 2004 |
| Subtaxa | |
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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
[edit | edit source]
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
[edit | edit source]Cephalozoa includes the families Yorgiidae and Sprigginidae:
Yorgiidae
[edit | edit source]- † Archaeaspinus Ivantsov, 2007 (synonym of Archaeaspis)
- † Archaeaspinus fedonkini Ivantsov, 2001
- † Yorgia Ivantsov, 1999
- † Yorgia waggoneri Ivantsov, 1999
Sprigginidae
[edit | edit source]- † 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 genera Andiva, Ivovicia and Podolimirus are also included in Cephalozoa, although are not apart of any family:[7]
- † Andiva Fedonkin, 2002
- † Andiva ivantsovi Fedonkin, 2002
- † Ivovicia Ivantsov, 2007
- † Ivovicia rugulosa 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.[8]
See also
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References
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