Tuzoia
sp
Phylum Arthropoda,
Subphylum Crustacea, Class Malacostraca, Subclass Phyllocaridae
Geological
Time: Early Middle Cambrian, (~525 million years ago)
Size (25.4
mm = 1 inch): Fossil is 50 mm long by 40 mm across on a 175 mm by 150
mm and 145 mm by 105 mm matrix
Fossil Site:
Comet Shale Member, Pioche Formation, Lincoln County, Nevada
Fossil Code:
WF06
Price: $600.00
|  Description:
This unusual fossil is an example of a rarely-seen Phyllocarid known
as Tuzoia. It is a bivalved crustacean, most well known for its
distinctively-reticulated carapace, 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 genus is known from the Burgess Shale and from Early/Middle
Cambrian deposits of Utah. Species are largely distinguished by
the presence and placement of spines on the carapace. Few examples
of the genus are known from more than the carapace, as seen here.
Note the intricate polygonal  decoration
to the carapace. 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. Note the partial trilobite in the
upper right corner of the first photograph. It is known as Eokochaspis
nodosa, a member of the order Ptychopariida, family Ptychopariidae.
Reference:
A New Soft-bodied Fauna: The Pioche Formation of Nevada, Bruce S.
Lieberman, Journal of Paleontology, Jul 2003.
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