Burgess Shale-type fauna

[2] The fauna is composed of a range of soft-bodied organisms; creatures with hard, mineralised skeletons are rare, although trilobites are quite commonly found.

[2] The fauna of the Burgess Shale lived in the photic zone, as bottom-dwelling photosynthesisers are present in the assemblage.

The outer parts of the top surfaces of the flaps have grooved areas which are thought to have acted as gills.

The 8 chordate species include Myllokunmingia, possibly a very primitive agnathid and Haikouichthys, which may be related to lampreys.

[7] Anomalocaris was a mainly soft-bodied swimming predator which was gigantic for its time (up to 70 cm = 2¼ feet long; some later species were 3 times as long); the soft, segmented body had a pair of broad fin-like flaps along each side, except that the last 3 segments had a pair of fans arranged in a V shape.

Unlike Kerygmachela and Pambdelurion (see above), Anomalocaris apparently had no legs, and the grooved patches which are thought to have acted as gills were at the bases of the flaps, or even overlapping on to its back.

The two eyes were on relatively long horizontal stalks; the mouth lay under the head and was a round-cornered square of plates which could not close completely; and in front of the mouth were two jointed appendages which were shaped like a shrimp's body, curved backwards and with short spines on the inside of the curve.

When organisms that were not preserved are entered into the equation, the shelly fossils probably represent about 2% of the animals that were alive at the time.