The evolution of the Mollusca is the way in which one of the largest groups of invertebrate animals evolved. This phylum of animals includes gastropods, bivalves, scaphopods, cephalopods, and several other groups. The fossil record of mollusks is relatively complete, and they are well represented in most fossil-bearing marine strata. Very early organisms which have been compared to molluscs include Kimberella and Odontogriphus.
An understanding of molluscan phylogeny dating from 2006 is shown below, as a horizontal cladogram (source:):
Further reading