Cambrian Period

 

The Cambrian Period is the beginning of the Phanerozoic Eon and the Paleozoic Era. Approximately eight ninths of the earth history had already taken place when the Cambrian began. Cambrian rocks formed between 542 and 488 million years ago, i.e., Cambrian sediments represent 54 million years of earth history.

Animals representing every known phyla appeared in the Cambrian fossil record. This sudden appearance of a variety of animals previously unknown in earlier rocks is often referred to as "the Cambrian explosion." The most famous formation for Cambrian fossils is the Burgess Shale in the Canadian Rockies.

Trilobites are common fossils in Cambrian rocks. Here are some examples:

 

 

Wheeler Shale, Delta, UT

This formation is known for trilobites but also contains may other creatures. In some layers, soft parts of the animal are perserved similar to contemporaneous material from the Burgess Shale.


Elrathia kingii Meek

Elrathia kingii Meek

Ptychagnostus sp.

Bathyuriscus sp.
The arrow points to the Bathyuriscus specimen. There are two agnostids (circled) as well: a tiny complete specimen to the right of the dime and a portion of one above the dime. There are pieces of an Elrathia in the lower, right corner.

Kinzer Formation, Lancaster, PA
Balanus concavus Bronn

Balanus concavus Bronn

Balanus concavus Bronn

Balanus concavus Bronn

For people who have access to this formation, it continues to yield impressive specimens. Mine came from an old collection.

Olenelllus getzi Dunbar

Olenelllus getzi Dunbar