This
unique Cambrian inchnofossil comes out of a sensational
sandstone formation in Central Wisconsin that was once a tidal
beach, resulting in the distinctive ripples you see on the matrix
surface. At present, it is generally accepted that the age of this
sandstone unit is upper Cambrian and thus represents an outlier
of the Mount Simon Sandstone. This quarry has been producing some
intriguing trace or ichnofossils, including huge madusae,
tentacled jellyfish, Diplichnites,
Protichnites,
and the Climactichnites
ichnogenus you see here, among others.
The
depositional environment in this quarry varies from very shallow
marine
to aerial. This is very significant as the ichnofossils from this
locality may be the earliest evidence of large organisms and carnivores
abandoning their marine habitat to utilize the terrestrial environment.
These ichnofossils may pre-date the Cambrian-Ordovician trackways
from Canada just described in the May 2002 issue of Geology.
Climachtichnites
has been described as looking like the track of a motorcycle that
drove across rippled sand. The ripples in the sandstone confirm
that the layer is a bedding plane that was once a Cambrian intertidal
zone. If Climachnichnites is a trackway, the traverse ridges can
be viewed as made by muscular undulation as the animal motivated
through the sand above the water. Also note the ridges on the margins
on the tracks, the same as the ridges that build on either side
of blade of a bulldoser. One theory of Climactichnites is that it
was made by a large slug, others believe a mullusk, and still others
posit an animal in an unknown Phylum that did not survive much beyond
the Cambrian.
This
particular specimen is one of the best Climactichnites fossils to
emerge from the Krukowski quarry. Climactichnites was locomoting
straight accross this ancient Cambrian beach, leaving this trackway
that measures 3 1/2 feet in length. It took four hours with a gas-powered,
diamond blade saw to cut this bad boy down to its current size,
and that does not include what it took to cut it out of the quarry.
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