2.55" Ordovician Septate Gastropod & Oncoceratid Association -Wisconsin

Ordovician Septate Gastropod & Oncoceratid Association -Wisconsin #216424

This is a 2.55" wide fossil association containing a Middle Ordovician septate gastropod (Ecculiomphalus undulatus) and an oncoceratid (Beloitoceras sp.) fossil. This specimen is part of an old collection from the Grand Detour Formation in Rock County, Wisconsin. The fossils have been partially exposed from the rock it was found in.

The gastropod measures 1.5" long and the oncoceratid measures 1.05" long.

Gastropods, or snails, have been around since the Late Cambrian period. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. There are 611 known families of gastropods, of which 202 families are extinct and appear only in the fossil record.

Oncoceratids are curved nautiloid cephalopods that have been identified from the Middle Ordovician up to the Late Silurian. Richardsonoceras is known for having a stronger convex curvature than other cephalopods in the family Oncoceratidae.