Discover

Contents

Structure

Phylogeny

External links

References

Structure

The conularids are fossils preserved as shell-like structures made up of rows of calcium phosphate rods, resembling an ice-cream cornet with sixfold symmetry, and usually four prominently-grooved corners. New rods were added as the organism grew in length; the rod-based growth falsely gives the fossils a segmented appearance. Exceptional soft-part preservation has revealed that soft tentacles protruded from the wider end of the cone, and a holdfast from the pointed end attached the organisms to hard substrate.

Phylogeny

About 20 genera and 150 species are known,[2] but except for a few local occurrences, Conularids are relatively uncommon.
The conularids were originally thought to be anthozoan cnidarians. However, the lack of septa or other features diagnostic of anthozoans led researchers to abandon this hypothesis.
Ivantsov and Fedonkin (2002) posit that the conularids were ancestrally tri-radially symmetrical, as typified with ''Vendoconularia'', typical of the structure seen in Vendozooans. Conularids are not generally thought to be a part of the Ediacaran biota, if only because of their fossil record.
It is now also thought that the conulate trilobozoans derived their four-fold symmetry from a six-fold symmetry, as seen in Vendoconularia, which, in turn, was originally derived from the ancestral disk-like trilobozoans' three-fold symmetry.

External links

★

★ http://www.uga.edu/strata/cincy/fauna/conulariida/Conularia.html

References

Devonian and Mississippian conulariids of North America. Part A. General description and Conularia. Ann Carnegie Mus 55 (15) : 375 [Zoological Record Volume 123]

★ Babcock, L.E. 1991. The enigma of conulariid affinities. Pp. 133-143 in A.M. Simonetta and S. Conway Morris (eds.). The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.

★ Ivantsov, A.Y. & M.A. Fedonkin 2002. Conulariid-like fossil from the Vendian of Russia: A metazoan clade across the Proterozoic/Palaeozoic boundary. ''Palaeontology'' '45'(6): 1219-1229.

★ Van Iten, H. 1991. Evolutionary affinities of conulariids. Pp. 145-155 in A.M. Simonetta and S. Conway Morris (eds.). The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.