Cephalozoa

Short description: Extinct class of marine animals

Cephalozoa

Temporal range: Ediacaran 571–551 Ma

PreЄ

Fossil of Yorgia waggoneri, a cephalozoan found on the shores of the White Sea.
Scientific classification
Kingdom:  |

Animalia

Phylum:  |

†Proarticulata

Class:  |

†Cephalozoa

Fedonkin, 1985

Subtaxa

* †Andiva
* †Ivovicia
* †Yorgiidae Ivantsov,[1] 2001
* †Sprigginidae Glaessner,[2] 1958

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.

## Contents

* 1 Description
* 2 Taxonomy
* 2.1 Yorgiidae
* 2.2 Sprigginidae
* 3 See also
* 4 References

## Description

Yorgia waggoneri organization diagram.

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:

Fossil of Andiva ivantsovi.

* Andiva Fedonkin, 2002
* Andiva ivantsovi Fedonkin, 2002

Recent studies indicate that the family Yorgiidae could be included or closely related to the class Vendiamorpha.[7]

## See also

* Ediacaran fauna

## References

1. ↑ 1.0 1.1 Ivantsov, A. Y. (2001). "Vendia and Other Precambrian "Arthropods"" (in en). pp. 335–343. https://www.academia.edu/2605872/Vendia_and_Other_Precambrian_Arthropods_.
2. ↑ 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"
3. ↑ Ivantsov, A. Yu (2004). "New Proarticulata from the Vendian of the Arkhangel’sk Region" (in en) (PDF). pp. 247–253. http://vend.paleo.ru/pub/Ivantsov_2004_eng.pdf.
4. ↑ Ivantsov, A. Y.; Malakhovskaya, Y. E. (2004). "Some Problematic Fossils from the Vendian of the Southeastern White Sea Region" (in en). pp. 1–9. http://www.vend.paleo.ru/pub/Ivantsov_et_al_2004_eng.pdf.
5. ↑ 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.
6. ↑ Ivantsov, Andrey Yu (2007). "Small Vendian transversely Articulated fossils" (in en). pp. 113. doi:10.1134/S0031030107020013. https://www.academia.edu/2352394/Small_Vendian_transversely_Articulated_fossils.
7. ↑ "Fossilworks: Vendiamorpha". http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=342808.

Wikidata ☰ Q30750018 entry

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