Cephalozoa

Extinct class of marine animals

Cephalozoa

Temporal range: Ediacaran 571–551 Ma

PreꞒ

Fossil of Yorgia waggoneri, a cephalozoan found on the shores of the White Sea.
Scientific classification
Domain:  | Eukaryota
Kingdom:  | Animalia
Phylum:  | †Proarticulata
Class:  | †Cephalozoa
Ivantsov, 2004
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.

## Description

[edit]

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

[edit]

Cephalozoa includes the families Yorgiidae and Sprigginidae:

### Yorgiidae

[edit]

* † Archaeaspinus Ivantsov, 2007 (synonym of Archaeaspis)
* † Archaeaspinus fedonkini Ivantsov, 2001
* † Yorgia Ivantsov, 1999
* † Yorgia waggoneri Ivantsov, 1999

### Sprigginidae

[edit]

* † 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 is sometimes included in 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

[edit]

* Paleontology portal
* Zoology portal
* Russia portal

* Ediacaran fauna

## References

[edit]

1. ^ a b Ivantsov, A. Y. (2001). "Vendia and Other Precambrian "Arthropods"". Paleontological Journal. 35 (4): 335–343.
2. ^ Fedonkin, Mikhail A. (2007). The Rise of Animals: Evolution and Diversification of the Kingdom Animalia. Baltimore (Md.): JHU Press. ISBN 978-0-8018-8679-9.
3. ^ Ivantsov, A. Yu (2004). "New Proarticulata from the Vendian of the Arkhangel'sk Region" (PDF). Paleontological Journal. 38 (3): 247–253.
4. ^ 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. 38 (1): 1–9\. Archived from the original (PDF) on 2007-07-04. Retrieved 2021-08-11.
5. ^ 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.
6. ^ Ivantsov, Andrey Yu (2007). "Small Vendian transversely Articulated fossils". Paleontological Journal. 41 (2): 113–122\. Bibcode:2007PalJ...41..113I. doi:10.1134/S0031030107020013.
7. ^ "Vendiamorpha". Paleobiology Database. Retrieved 17 December 2021.

* v
* t
* e

Proarticulata

* Kingdom Animalia
* Subkingdom Eumetazoa
* (unranked) ParaHoxozoa
* (unranked) Bilateria

Vendiamorpha|

| Vendiidae|

* Vendia
* Paravendia
* Karakhtia

|

Dipleurozoa|

| Dickinsoniidae|

* Chondroplon?
* Dickinsonia
* Palaeoplatoda
* Windermeria

|

Cephalozoa|

* Andiva
* Cephalonega
* Ivovicia
* Tamga

Yorgiidae|

* Archaeaspinus
* Yorgia

Sprigginidae|

* Cyanorus
* Marywadea
* Praecambridium
* Spriggina

Unclassified|

* Armillifera
* Lossinia
* Ovatoscutum?
* Podolimirus

Part of the Ediacaran biota

Taxon identifiers

Cephalozoa|

* Wikidata: Q30750018
* Wikispecies: Cephalozoa
* IRMNG: 11915625

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