- CRETACEOUS AMMONITES FROM THE UNITED STATES
A number of species of cretaceous ammonites are found in
the Pierre and Bearpaw Shales of Montana and Fox Hills Sandstone
of South Dakota. Some were quite large, up to 30 inches in diameter.
They were a favorite food of the Mosasaurs which frequently dined
on this Cretaceous "escargot".
Cretaceous ammonites have extremely intricate suture patterns.
They are often found with a colorful nacreous shell coating which
reflects beautiful color flashes when coated with a clear lusterous
resin. Some species flash bright red, green and lavendar colors
and are prized as a gemstone called "Ammolite". Other
species have soft opal colors much like "mother of pearl".
The intricate suture patterns are revealed when the nacreous
shell coating is removed.
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