Pennsylvanian Fossils


Named for deposits in the state of Pennsylvania, sequences of coarse to fine material with layers of coal along with evidence of repeated ice ages in the southern hemisphere indicate that sealevel rose and retreated many times during the 34 million years of the Pennsylvanian period.

Minturn Formation, Eagle, Colorado

I came across a road cut near Eagle and spend about two hours collecting. There was a layer of limstone over a very friable shale. I interpreted this as a coral reef with a lagoon.

First from the limestone, crinoids, bryozoa, and brachiopods. Notice in the second specimen what looks like a wire about an inch long in the bottom middle. See the brachiopods below.


Blowup of wire, note the attachement at the shell forming a curve in the limestone.

Crinoid: The far right specimen is encrusted with a bryozoa.
Now for the specimens from the shale.

The brachiopod (Antiquatonia coloradoensis) in the upper left has small bumps on the surface. These are the attachments of spines, the wire in the middle specimen above. You can see the curve of the shell perpendicular to the spine, i.e, wire. Other brachiopods include: Composita subtilita; and Anthracospirifer occiduus.

Two bellerophon species

A bivalve: Bivalves were the poor cousins to brachiopods during the Paleozoic but got their revenge after many brachiopod species were killed at the end of the Permium.

A collapsed nautaloid

Francis Creek Shale, Illinois

A fern

A fern leaflet

St. Clair, Pennsylvania

This site is famous for a variety of Pennsylvanian plants.