Yunnanozoon
The
Yunnanozoon is a suspected
chordate or
hemichordate from the Lower
Cambrian beds of
Xiangchiang in
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. 13 pairs of symmetrically arranged
gonads have been identified as are possible gill slits. However, some authors think that
Yunnanozoon is closely related to the
chordate Haikouella and that
Yunnanozoon is probably achordate rather than a hemichordate. A link close relationship between
Yunnanozoon and the phylum
Vetulicolia has also been proposed.
There is one species
Yunnanozoon lividum (Chen et al., 1995).
*Shu, D., Zhang, X. and Chen, L. 1996. Reinterpretation of Yunnanozoon as the earliest known hemichordate,
Nature. 380:428-430 (
04 April 1996). [
1] - accessed
December 3 2005*A picture can be found at http://www.gs-rc.org/repo/repoe.htm
