Aegirocassis benmoulai Van Roy 2015

Ordovician

Lower Fezouata Formation

Eastern flank of Jbel Tigzigzaouine, facing Oued Ezegzaou, Morocco.

90mm appendage on 164mm slab.  Rare example of one of the largest arthropods of all time.

Soft-bodied. Arthropod.

Aegirocassis is a genus of anomalocaridid arthropod that was one of the largest of all arthropods that 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.

So far, Aegirocassis is known only from the Early Ordovician of Morocco.  Anomalocaridids were once thought to have died out by the end of the Cambrian but a new genus was described from the Early Devonian of Germany (Hunsruck Shale) 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!