|
The majority of what is currently the eastern United States was a vast primordial swamp during the Pennsylvanian Period. This primeval rain forest/wetland was home to amphibians, cockroaches, huge dragonflies and other crawling creatures. Reptiles had not yet begun to emerge. Untold generations of plants, many were of very large size, lived and died. Their remains were buried in the water and muck in which they grew. They mixed with the remains of earlier plants which had died and were covered by sediments. Those plants which were covered by sediments quickly enough were preserved from immediate decay. Over millions of years these layers of biomass were covered by more layers of sediment and may have been subject to mountain building. These layers of biomass eventually turned into coal which we mine today. Many of these layers turned into shale (such as the Pottsville Formation) in which horsetails, ferns, seed ferns, and rushes from the Pennsylvanian Period have been preserved in wonderful detail. Alethoptertis (the seed ferns) that were common in this stratum are thought to be the forerunner of today's flowering plants. These ferns were very much like our modern varieties. The difference is that they were tree-like in size with some of them reaching 40 feet in height with trunks two feet in diameter.
The white coating found on these fossil leaf plates is pyrophyllite. It is a soft, talc-like mineral, that has replaced some of the vegetable matter.
There are four common types of ferns from this location. Alethopteris fern leaf tips are generally pointed. Pecopteris fern leaf tips are more rounded. Annularia, is a member of the rush family, and has a leaf with lobes that look like a clover leaf. Neuropteris is usually found as a singular leaf.
The pointed tips of the leaves of these fronds, in the first image, would indicate that this fern is Alethopteris. At the top of the second image is a small rust colored frond with lobed leaves. This frond is Annularia. The rest of the fronds, on this side of the plate, are Alethopteris.
Alethopteris/Annularia - fossil ferns
|
|
|
Quantity in Basket:
None
Code: PFF-103
Price: $12.00
Shipping Weight: 0.53 pounds
|
|
Species: Alethopteris and Annularia
Time: Pennsylvanian Period, approximately 300-280 million years ago.
Location: Pottsville Formation, St. Clair, Pennsylvania
Dimensions: 5-3/8" x 4-1/2" x 5/8"
|
|