Shell Fossils

Shell Fossils – Monotis subcircularis.

Shells in Shale – Early Cretaceous.

This sample is of fossil shells from the Peace River region of northern BC. They are fossils of shells of the bivalve species Monotis Subcircularis, which lived during the Triassic, between 247 and 205 million years ago. Bivalves first evolved in the Cambrian, over 500 million years ago, and many species still exist today, including clams, mussels and scallops.

Bivalves are a class of mollusc with two shells joined at a hinge. Their shells are usually made of calcium carbonate, which is hard and easily preserved, making bivalve fossils relatively common. Different bivalve species inhabit different environments and existed at different times in geological history. By identifying the species, geologists can estimate how old a rock is and what conditions it formed under, whether in a lake, or a beach, or further offshore in deeper water.

These fossils are impressions made of the shell in mudstone. When the creatures died, they settled to the seafloor onto the soft mud. Over time, the mud has been lithified, or turned to stone, preserving these impressions for over 200 million years.



Specimen Information

Store: Association for Mineral Exploration


Accession #: 1676

Primary Fossil:  Monotis subcircularis

Secondary Feature: Shale

Site Locality: Peace River

Location: Peace River, British Columbia

Special Features: n/a

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