Prospects & Overviews
Cephalopod origin and evolution: A congruent picture emerging from fossils, development and molecules
Extant cephalopods are younger than previously realised and were under major selection to become agile, shell-less predators
Article first published online: 17 JUN 2011
Copyright © 2011 WILEY Periodicals, Inc.
Volume 33, Issue 8, pages 602–613, August 2011
How to Cite
Kröger, B., Vinther, J. and Fuchs, D. (2011), Cephalopod origin and evolution: A congruent picture emerging from fossils, development and molecules. Bioessays, 33: 602–613. doi: 10.1002/bies.201100001
- Issue published online: 19 JUL 2011
- Article first published online: 17 JUN 2011
- Cambrian explosion;
- divergence estimate;
- fossil record;
Cephalopods are extraordinary molluscs equipped with vertebrate-like intelligence and a unique buoyancy system for locomotion. A growing body of evidence from the fossil record, embryology and Bayesian molecular divergence estimations provides a comprehensive picture of their origins and evolution. Cephalopods evolved during the Cambrian (∼530 Ma) from a monoplacophoran-like mollusc in which the conical, external shell was modified into a chambered buoyancy apparatus. During the mid-Palaeozoic (∼416 Ma) cephalopods diverged into nautiloids and the presently dominant coleoids. Coleoids (i.e. squids, cuttlefish and octopods) internalised their shells and, in the late Palaeozoic (∼276 Ma), diverged into Vampyropoda and the Decabrachia. This shell internalisation appears to be a unique evolutionary event. In contrast, the loss of a mineralised shell has occurred several times in distinct coleoid lineages. The general tendency of shell reduction reflects a trend towards active modes of life and much more complex behaviour.