Peltoceratoides and Cosmoceras Ammonites
sp. & Cosmoceras sp.
(25.4mm=1 inch): Peltoceratoides: 51 mm diameter Cosmoceras: 45 mm diameter
matrix: 88 mm by 80 mm
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.
ammonite pictures to enlarge