AMMONITE STEPHANOCERAS

AMMONITE STEPHANOCERAS

A large solid Ammonite Stephanoceras sp. fossil on matrix.

Stephanoceras sp.
Middle Jurassic (Bajocian).
Calvados Department.

Location:
Cean, France.

Dimensions:
Ammonite Only: 9.3cm x 7.3cm x 4.2cm.  680g (including matrix).

Ammonites are an extinct group of marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda.  These molluscs are more closely related to living coleoids (i.e., octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species.  The earliest ammonites appear during the Devonian, and the last species died out during the Cretaceous–Paleogene extinction event.

Out of all of the infinite numbers in the world, there are precious few that are given their own letter from the all-too-finite Greek alphabet.  The golden ratio, also known as phi (usually pronounced “fie” in English), is one of those few.  An irrational number that begins 1.618…, it describes an important kind of geometrical proportion specifically, an elegant way to divide a line segment.