Evolution of Mollusca

Diagram of primitive mollusc viewed from left side. Hypothetical mollusc ancestor. From Encyclopædia Britannica Eleventh Edition.

The current understanding of molluscan phylogeny is shown below.

Horizontal cladogram (source:):

Mollusca   Aplacophora  Solenogastres Caudofoveata  Testaria  Polyplacophora  Palaeoloricata Neoloricata Conchifera  Monoplacophora  (unnamed)   Cyrtosoma  Gastropoda Cephalopoda  Diasoma  Rostroconchia  (unnamed)  Scaphopoda Bivalvia Basal Mollusca phylogeny.

Early organisms which have been compared to molluscs include Kimberella and Odontogriphus.

Further reading

• From sea to land and beyond – New insights into the evolution of euthyneuran Gastropoda (Mollusca)