Animalia, Phylum Arthropod stem group,
Class Dinocaridida, Order Radiodonta, Family Anomalocarididae
Time: Middle Cambrian
fossil is 35 mm across on a 125 mm by 65 mm matrix
Upper Wheeler Shale, Millard County, Utah, USA
This is a partial oral disc of the “Terror Of The Cambrian”,
Anomalocaris. The members of this group of enigmatic creatures are
known from Asia, Australia, Europe, and North America, and are thought
by many to be closely allied with the Arthropda, a position not
held by all researchers. Several have been described from Utah,
notably a 50 mm partial specimen of A nathorsti from the Marjum
Formation, but they are far more rare than those from Chengjiang
or the Burgess Shale. Many examples of Elrathia have been found
with bite marks, most typically on the right side, which are thought
to have been the result of an abortive attack by this Cambrian raider.
Indeed, this specimen is overlain by an impression of a trilobite
which may well have been its prey.
see a complete Anomalocaris
fossil from the older Pioche Formation of Nevada.