Xidazoon

Taxobox
name = "Xidazoon"
fossil_range = Cambrian


image_width = 240px
image_caption = Artist's concept of "Xidazoon stephanus"
regnum = Animalia
phylum = Vetulicolia
phylum_authority = Shu, et al. 2001
ordo = Vetulicolida
ordo_authority = Chen & Zhou 1997
familia = Didazoonidae
familia_authority = Shu & Han 2001
genus = "Xidazoon"
genus_authority = Shu, Conway Morris & Zhang 1999
species = "X. stephanus"
binomial = "Xidazoon stephanus"

The genus "Xidazoon" was erected by Shu, et al. (1999) based on fossils found in the Qiongzhusi (Chiungchussu) Formation, Yu'anshan Member (Eoredlichia zone), Lower Cambrian, Haikou, (Kunming), about 50 km west of Chengjiang, China. It currently consists of the single species "Xidazoon stephanus".

The fossils show that the body of the animal was divided into two parts. The anterior part of the body is moderately inflated, with a prominent mouth circlet. It has faint transverse divisions towards the front, but is otherwise smooth. The mouth circlet consists of about 30 plates divided into inner and outer regions. The anterior section has five structures on each side, which are interpreted as gills. A dark region running close to the ventral and posterior margins is interpreted as an endostyle. The condition of the anterior portion of the fossils suggests that it was thin-walled, i.e., that the anterior portion was largely hollow. The posterior part of the body tapers towards front and back (diamond-shaped), and is divided into six segments covered in cuticle with three less well-defined segments at the anterior end. There are short spines at the posterior tip. The authors describe an alimentary canal with terminal openings and a rectum with what might be dilator muscles.

ee also

* Maotianshan shales

References

*Shu, D.-G., Conway Morris, S., Zhang, X.-L., Chen, L., Li, Y. and Han, J. 1999. A pipiscid-like fossil from the Lower Cambrian of south China, "Nature", 400:746-749. (August 19, 1999). [http://www.paper.edu.cn/project/nwu1/nwu1-9.pdf] - URL retrieved December 1, 2005.
*Shu, D.-G., Conway Morris, S., Han, J., Chen, L., Zhang, X.-L., Zhang, Z.-F., Liu, H.-Q., Li, Y., and Liu, J.-N. 2001. Primitive Deuterostomes from the Chengjiang Lagerstätte (Lower Cambrian, China), "Nature", 414:419-424. (November 11, 2001). [http://www.paper.edu.cn/project/nwu1/nwu1-4.pdf] . - URL retrieved December 2, 2005

External links

* [http://www.geolsoc.org.uk/template.cfm?name=OFNANP New phylum on the block]

* [http://cas.bellarmine.edu/tietjen/Evolution/vetulicola.htm Once We Were Worms]

* [http://www.paper.edu.cn/project/nwu1/nwu1-4.pdf Chu, et. al., Primitive Deuterostomes from the Chengjiang Lagerstätte]