Coeloscleritophoran

Coeloscleritophoran
Scientific classification
Kingdom: Animalia
Included groups
Halkierids Chancellorids

The Coelosclerithophorans are a polyphyletic group of organisms bearing hollow sclerites made of aragonite.

Their skeletons may be homologous to those of the molluscs,^[1] and Halkieria looks very much like a polyplacophoran. The shells of this group and the molluscs appear to have originated in the same fashion.^[1] However, there are several reasons to doubt this relationship,^[2] many of which may not pass muster.^[3]

There are two groups within the coeloscleritophorans: the Sachitids, to which Halkieria and Wiwaxia belong, and the Chancellorids. The Ediacaran fossil Ausia has been touted as an ancestral 'intermediate' between both of these groups.^[4]

These are common constituents of Lower Cambrian small shelly fossil assemblages.

References

1. ^ ^{a b} Bengtson, S. (1992). "The cap-shaped Cambrian fossil Maikhanella and the relationship between coeloscleritophorans and molluscs". Lethaia 25 (4): 401–420. doi:10.1111/j.1502-3931.1992.tb01644.x. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1502-3931.1992.tb01644.x 
2. ^ Yochelson, E. L. (1993). "Molluscan affinity of coeloscleritophorans". Lethaia 26 (1): 47–48. doi:10.1111/j.1502-3931.1993.tb01509.x.  edit
3. ^ Bengtson, S. (1993). "Molluscan affinity of coeloscleritophorans — reply". Lethaia 26 (1): 48–48. doi:10.1111/j.1502-3931.1993.tb01510.x.  edit
4. ^ Dzik, Jerzy (August 2009). "Possible Ediacaran Ancestry of the Halkieriids". In Smith, Martin R.; O'Brien, Lorna J.; Caron, Jean-Bernard. International Conference on the Cambrian Explosion (Walcott 2009). Abstract Volume. Toronto, Ontario, Canada: The Burgess Shale Consortium. 31st July 2009. ISBN 978-0-9812885-1-2. http://burgess-shale.info/abstract/dzik.