Aegirocassis benmoulai

Ordovician

Fezouata Formation

Mecissi-Zagora Region, Draa Valley, Morocco.

30mm anomalocaridid appendage on 98mm slab.

Soft-bodied. Arthropod.

Aegirocassis is a genus of anomalocaridid known only from the Early Ordovician of Morocco.  It was one of the largest of all arthropods that have ever lived, reaching about 6 1/2 feet long and was almost certainly the largest animal of its time.  Like the largest animal of our time, the blue whale, it has been determined to have been a filter-feeder that descended from predatory ancestors.

Anomalocaridids were once thought to have died out by the end of the Cambrian but one was described from the Early Devonian of Germany in 2009.

Have a look at this amazing 3D model of Aegirocassis courtesy of Google and darwinmuseum.ru. Click on the arrows at the bottom right corner to see it full screen!