Mazon Creek Jellyfish

Various jellyfish from the Mazon Creek Lagerstätten. For size reference, Octomedusa's bell would have been about as wide as a dime.

The upper left is Octomedusa pieckorum, a small, eight-tentacled jelly that is one of the most numerous fossils in Mazon Creek.

The upper right is Essexella asherae, a larger, weirder jelly that had a long "veil" covering its long tentacles.

Lower right is Lascoa mesostaurata. Contrary to what its species name might suggest, it was not a Stauromedusa ("stalked jellyfish"), but a primitive relative of the modern Moon Jelly, Aurelia aurita. Because L. mesostaurata had much fewer and larger rim-tentacles, it may have been a predator of (very small) nekton, rather than zooplankton like A. aurita.

Lower left is Anthracomedusa turnbulli, the oldest known box jelly.