by most authors. Together the three phyla are grouped as the grade Vendobionta.The petalonamids are often considered as early diverging animals before animals with true tissue organisation started to appear.

References

External links

* Tree of Life web project, US National Science Foundation. 2002. 6 January 2006.
*
*Evers, Christine A., Lisa Starr. Biology:Concepts and Applications. 6th ed. United States:Thomson, 2006. .
* St. Petersburg. 2005
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*Nielsen,

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