Iridescent Peltoceratoides and Cosmoceras Ammonites

Name: Peltoceratoides sp. & Cosmoceras sp.

Age: Jurassic, Callovian Stage

Size: mm (25.4mm=1 inch): Peltoceratoides: 51 mm diameter Cosmoceras: 45 mm diameter matrix: 88 mm by 80 mm

Location: Ulyanovsk, Russia

Peltoceratoides and Cosmoceras AmmonitesDescription: A magnificent example of the ammonite Peltoceratoides sp. in association with a Cosmoceras of the Callovian Stage (161 m.y.a) deposits of Russia. The taxon derives its name from its relationship to Peltoceras. Ammonites of this degree of preservation are difficult to come across singly, much less as a pair. The high degree of preservation of the 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 natural art of the ammonite plus the artistic sculping of the preparator make for a beautiful fossil.

click ammonite pictures to enlarge

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