Quenstedticeras and Paracadoceras sp.
Geological Age: Jurassic Callovian Stage
Size (25.4 mm = 1 inch): Four 38-63 mm Cosmoceras with three 25-40 mm diameter Paracadoceras ammonites
Fossil Site: Ulyanovsk, Russia
Code: RA170
Price: $135.00 - sold
 Description:
A superb example of an assemblage of ammonites of the genera Cosmoceras
and Paracadoceras of the Callovian Stage (161 m.y.a) deposits of Russia,
joined together by Drusy pyrite. The least common taxon is the Paracadoceras,
which is distinguished by the different cross-sectional aspect. Ammonites
of this degree of preservation are difficult to come across. The high
degree of preservation of natural mother-of-pearl shell makes it appear
to be preserved as fire opal. This is a consequence of light passing
through the various layers of aragonite and conchiolin deposited by
the ammonite in life. The lack of acidity in the depositional environment
allowed them to be preserved as you see here. The environment was
also anoxic, leading to formation of Iron Pyrite (Fool’s Gold).
They are well presented from every aspect. |
