(Narao - After a group of lakes in British Columbia near where the
first specimens were found).
Named By: Charles Doolittle Walcott - 1912.
Classification: Arthropoda, Chelicerata, Nektaspida, Naraoiidae.
Species: N. compacta (type), N. bertiensis, N. spinifer, N. spinosa, N. tianjiangensis.
Diet: Uncertain, may have been either a carnivore or a detritivore.
Size: Around 20 to 45 millimetres long.
Known locations: Australia, Canada - Burgess Shale, China and USA.
Time period: Lower Cambrian to Late Silurian.
Fossil representation: Multiple specimens.
different to other trilobites that it was actually misidentified as a
crustacean until some specimens were dissected by Harry Blackmore
Willington. The reason why Naraoia was not
immediately identified as
a trilobite was because the multiple segments that reveal it to be one
were hidden from view by two large shields called the cephalon (the
forward one over the head) and pygidium (the one at the back that
covers the rear portions of the body.
Naraoia is noted for having a large digestive tract with width between one sixth and one fifth the width of the body. This broad gut has been interpreted as both being for processing a large amount of sediment (for the extraction of organic matter within) as well as swallowing prey animals. There are no eyes present to suggest predation, but numerous antennae radiated out from the size, and these might have been used to feel for nearby prey animals.
Although the body of Naraoia was covered by two large plates, fossil specimens reveal that the joint between these could bend by as much as ninety degrees. Additionally large distal lobes would have been suitable for shifting large quantities of sediment, and their placement along with the other side wards antennae have all been taken as adaptations to a burrowing lifestyle.