Canadaspis
perfecta
Phylum Arthropoda
(Euarthropoda), Class Malacostraca, Subclass Phyllocarida, Order Canadaspidida,
Family Canadaspididae
Geological
Time: Early Middle Cambrian, (~525 million years ago)
Size (25.4
mm = 1 inch): Fossil is 45 mm overall, Carapace 30 mm long by 30 mm across,
on a 180 mm by 160 mm matrix
Fossil Site:
Comet Shale Member, Pioche Formation, Lincoln County, Nevada
Fossil Code:
WF13
Price: $1800.00
- sold
|  Description:
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 deposit
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. The
specimens are often somewhat faint, as here. The specimen has been
water wet to heighten contrast in the last photographs. Regardless,
this is a rare specimen, little seen outside of an academic collection.
Most of the outcrops are on BLM land which is not available for
collecting. This material however comes from a ranch on private
land.
Reference:
A New Soft-bodied Fauna: The Pioche Formation of Nevada, Bruce S.
Lieberman, Journal of Paleontology, Jul 2003.
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