Cephalozoa
Extinct class of marine animals
From Wikipedia, the free encyclopedia
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.
Ivantsov, 2004
| Cephalozoa Temporal range: Ediacaran | |
|---|---|
| |
| Fossil of Yorgia waggoneri, a cephalozoan found on the shores of the White Sea. | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | †Proarticulata |
| Class: | †Cephalozoa Ivantsov, 2004 |
| Subtaxa | |
| |
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, 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[6]
- † 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:[7]
- † 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.[8]
