Triarthrus
eatoni
Trilobites
Order
Ptychopariida, Family Olenidae
Geological
Time: Late Ordovician
Size: 10
mm long (12 mm with antennae)
Fossil Site:
Lorraine Shale, Lewis County, New York
Description:
There are but a handful of fossil sites (Konservat-Lagerstätten)
where trilobite soft parts are preserved, especially the trilobite
legs and the delicate antennae. These include the Chengjiang
Maotianshan Shales of China, Bundenbach in Germany, the Burgess
Shale of Canada, and Beecher’s Trilobite Bed of the Lorraine
Shale in New York. Another New York Lagerstätte was discovered
in 2005 with exquisitely preserved trilobites, as the ones shown
here. This site in Lewis County, New York exposes the Lorraine
Shale. These trilobites were ostensibly rapidly buried in oxygen-starved
sediment (anoxic) enabling extremely fine detains to be pyritized,
including replacement of soft tissues. Note in the ventrally
exposed trilobite that the biramous limbs are clearly evidenced,
as well as the antennae abductors and mandibles. The gold
pyrite is a striking contrast to the dark matrix. This fine
example is preserved in ventral aspect with both antennae and
many biramous limbs
in
evidence. It is one thing
to find such a trilobite, and quite another to prepare it with
pneumatic equipment with fine, soft grit so that the exquisite
details are not lost – numerous painstaking hours are required
under the microscope.
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