Yunnanozoon

Taxobox
name = "Yunnanozoon"


fossil_range = Early Cambrian
regnum = Animalia
phylum = Hemichordata?
genus = "Yunnanozoon"
binomial = "Yunnanozoon lividum"
binomial_authority = Chen "et al.", 1995

"Yunnanozoon lividum" ("Livid Animal of Yunnan") is a suspected chordate or hemichordate from the Lower Cambrian, Chengjiang biota of Yunnan province, China.

"Yunnanozoon" is similar to the form "Haikouella", which is almost certainly a vertebrate. Still, there are anatomical differences from "Haikouella", including a smaller stomach and much larger (1 mm) pharyngeal teeth. Yunannozoon is not known for sure to possess many features like heart, gills, etc. that are known from well preserved specimens of "Haikouella". "Yunnanozoon" somewhat resembles the Middle Cambrian "Pikaia" from the Burgess shale of British Columbia in Canada. Thirteen pairs of symmetrically arranged gonads have been identified as have possible gill slits. However, some authors think that "Yunnanozoon" is closely related to the chordate "Haikouella" and that "Yunnanozoon" is probably a chordate rather than a hemichordate. A close relationship between "Yunnanozoon" and the phylum Vetulicolia has also been proposed.

References

*Shu, D., Zhang, X. and Chen, L. 1996. Reinterpretation of Yunnanozoon as the earliest known hemichordate, "Nature". 380:428-430 (4 April 1996). [http://www.nature.com/nature/journal/v380/n6573/abs/380428a0.html] - accessed December 3 2005

External links

*A picture can be found at http://www.gs-rc.org/repo/repoe.htm