http:www'ndsu'nodak'eduinstructashworthwebpagesg303

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http//www.ndsu.nodak.edu/instruct/ashworth/webpag
es/g303/
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http//capp.water.usgs.gov/gwa/ch_j/J-text7.html
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http//files.dnr.state.mn.us/waters/groundwater_se
ction/mapping/cga/c14_wabasha/pdf_files/C-14_Plate
08.pdf
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CAMBRIAN SYSTEM in Minnesota Upper Cambrian
St. Croixian
Cross-bedded sandstones
In Minnesota and Wisconsin unconformable on
PreCambrian strata
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Climactichnites
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Climactichnites
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Climactichnites
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Spectacular trace fossils (Ichnofossils) Climac
tichnites resemble tracks made by a motorcycle
both is size and character. Described by Sir
William Logan in 1860, Climactichnites was
believed at that time to come from the oldest
sedimentary formation known the Canadian
formation is now known to be Upper Cambrian.
The fossil caused considerable controversy
among paleontologists, and speculation regarding
the track maker's identity abounded. Arthropods
with soft bodies were denied by the lack of
footprints. The possibility of a snail was denied
by the V-shaped ridges, and that no known
Cambrian snail or worm (even today) can account
for the tracks that can be six or more inches
wide.
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More recently, Damrow et. al. have suggested that
an alternative explanation for Climactichnites is
as a body fossil. Based on new fossils from a
sandstone quarry in central Wisconsin they
propose that the evidence shown on numerous
sandstone slabs is equally compatible with the
hypothesis that Climactichnites fossils are body
impressions of a gelatinous zooplankter that
floated into shallow water where they were
deposited gently across the extensive tidal sand
flats. The picture below links to more pictures
of what is surely the most impressive,
Climacticnites ever found in the Wisconsin quarry.
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Scyphozoans Jellyfish medusae
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The Cambrian was of great evolutionary
innovation, with many major groups of organisms
appearing within a span of about forty million
years. Trace fossils made by animals also show
increased diversity in Cambrian rocks, showing
that the animals of the Cambrian were developing
new ecological niches and strategies -- such as
active hunting, burrowing deeply into sediment,
and making complex branching burrows. Almost
every metazoan phylum with hard parts, and many
that lack hard parts, made their first appearance
in the Cambrian. Although almost all of the
living marine phyla were present, most were
represented by classes that have since gone
extinct or faded in importance. The Brachiopoda
for example, were represented by the relatively
primitive inarticulate brachiopods.
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• Other Cambrian invertebrates with mineralized
  skeletons included
• Trilobites, archeocyathids, inarticulate
  brachiopods, monoplacophorans, echinoderms.
• Cambrian echinoderms were predominantly
  unfamiliar and strange-looking types such as
  early edrioasteroids, eocrinoids, and
  helicoplacoids. Starfish and sea urchins had not
  yet evolved.
• In addition there were problematic conical
  fossils known as hyolithids.

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Trilobites
General morphology skeletal parts (from the
Treatise of Invertebrate Paleo)
Olenellus
Mostly members of the benthos
Bottom-dwellers
Plate of Upper Cambrian fossils from Mt.
Jubillee, Columbia River Valley, British
Columbia, described by Teiichi Kobayashi,1938
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Upper Cambrian trilobites from Wisconsin
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Inarticulate Brachiopods
living fossils Subphylum
Linguliformea (L. Camb. - Rec.) chitonophosphatic
shells
Fossil
Spatula-shaped shell with fleshy pedical
projecting from between The two valves
In burrow, organism retractile on a pedicle
Inarticulate brachiopods lack interlocking hinge
mechanisms and have the valves held together only
by muscles. Modern forms e.g. Lingula, burrow in
soft, muddy, dark-colored sediments and move up
and down within their burrows on a long leathery
or fleshy stalk-like extension (pedical). They
are found in marine or brackish water in poorly
-oxygenated estuaries and mud flats.
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Monoplacophorans primitive molluscs Possess
segmented muscles and organs
ancestral to later mollusc classes
Prior to 1952, the monoplacophorans were known
only from fossil shells from the Cambrian and
Devonian. Then in that year the 'Galathea'
expedition dredged up 10 living specimens of
Neopilina galathea. These two species are the
only known living representatives of this class
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Phylum uncertainClass HYOLITHA Marek,
1963Family HYOLITHIDAE Nicholson, 1872Genus
Hyolithes Eichwald, 1840
Reconstruction of the hyolithid animal
Fossils of Hyolithes