Canadsaspis Phyllocarid Fossil with Preserved Soft Tissue

Canadaspis perfecta

Phylum Arthropoda (Euarthropoda), Class Malacostraca, Subclass Phyllocarida, Order Canadaspidida, Family Canadaspididae

Geological Time: Early Middle Cambrian, (~525 million years ago)

Size: Fossil carapace 30 mm long by 30 mm across

Fossil Site: Comet Shale Member, Pioche Formation, Lincoln County, Nevada

Canadsaspis perfectaDescription: This unusual fossil is an example of a rarely-seen Phyllocarid known as Canadaspis perfecta. It is a bivalved crustacean, and comes from the Comet Shale Member of the Pioche Formation of Nevada. This depositCanadaspis spans the transition of Early to Middle Cambrian which saw the extinction of the Olenellid trilobites. It is just younger than the comparable material from the Chengjiana Biota of Yunnan Province, China and just older than the Burgess Shale Fauna of British Columbia, Canada. The species is also known from the Burgess Shale and from Early/Middle Cambrian deposits of Utah. A related species, Canadaspis laevigata is found in the Chengjiang deposits of China. Few examples of the genus are known from more than the carapace, so the preserved segmented abdomen seen here is quite rare.

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