Cryptolithus
bellulus
Trilobites
Order Asaphida, Family Trinucleidae
Geological
Time: Late Ordovician
Size: Trilobite
is 17 mm long by 20 mm wide on a 105 mm by 70 mm matrix
Fossil Site:
Pulaski Shale, Lorraine Group, Highmarket Township, Lewis County, New
York
Description:
With only about a half dozen localities known, trilobites with
soft tissue preservation are rare. A well-known site in the United
States is Beecher’s Trilobite bed where examples of Triarthrus,
Cryptolithus, and Cornuproetus are known. In 2005 a new location
in Lewis County was discovered which will take its place in this
select group as a site containing Triarthrus eatoni with preserved
appendages. This is another location that was found which in
addition to Triarthrus has Cryptolithus as well. These trilobites
were buried rapidly, resulting in an anxonic environment which
allowed for infilling with fine-grained pyritic deposits that
preserved the details seen here. The degree of pyritization is
less pronounced than that in the Triarthrus. This is a recently-discovered
site that is only some 2 meters square, and has Cryptolithus
far larger than others seen before. This fine example is preserved
in dorsal aspect. These trilobites are prepared using a very
fine 50 nanometer powder in order to preserve the pyrite. Note
the fine pitting to the cephalic rim (fenestrae) which are thought
by some to have been used in filter feeding of fine particulates
from the sediment.
|
Credit:
Fossil Mall Trilobites |