Half a Billion Year Old Jelly

Researchers report today in PLoS ONE that they have identified fossilized jellyfish that date back to 500 million years. The previous oldest-known cnidarian fossils were "only" 300 million years old. This new find pushes the origin of cnidaria back to at least the middle of the Cambrian. The fact that the fossils show traits that are diagnostic of modern taxa suggest that jelly origin may coincide with (or predate) the Cambrian Explosion (alternatively, modern-looking jellies may have evolved rather quickly during the Cambrian).

This new find should help shed some light on the origin and diversification of a group of critters that are generally not preserved well due to their soft bodies and also adds another piece of the puzzle of rapid diversification during the Cambrian.