Home | Exhibits | Life Through Time Exhibit | Pennsylvanian

Artists interpretation of a Pennsylvanian swamp (from Dana)

Mississippian

Pennsylvanian (Upper Carboniferous) 318.1 to 299.0 Million years ago

Permian

Plate Tectonic Reconstructions

The Pennsylvanian* saw the disappearance of the warm, shallow seas of the Mississippian, causing a dramatic change in marine life. The warm, clear seas of the Mississippian gave way to cool, muddy waters resulting in a decline in crinoids from which they never recovered. On land coal swamp forests thrived during this period. The dead plant material was laid down in huge amounts, gradually forming today's coal. Insects ruled the air. A dragonfly ancestor living in this Sub-period had a 29-inch wing inch wing span.

*The Pennsylvanian was named for the coal-bearing beds in Pennsylvania by J.J. Stevenson in 1888.

Pennsylvanian Animal (Metazoan) Fossils
Trilobites (ToL: Trilobites<Arthropoda<Ecdysozoa<Bilateria<Metazoa<Eukaryota)
	Trilobites are represented by Ditomopyge scilius.
Echinoderms (ToL: Echinodermata<Deuterostomia<Bilateria<Metazoa<Eukaryota)
	Sea Stars (Asteroidea). Free living echinoderms are represented by the Asterozoan, a starfish resting place.
	Crinoids (Crinoidea). Although declining, sea lilies are still found, as represented by Erisocrinus typus (white) and Stellarocrinus bilineatus. A large crinoid stem fossil is also shown.
	Sea cucumbers (holothuroidea) are soft bodied echinoderms, and thus rarely fossilized. The fossil remains of Achistrum sp., in positive and negative impressions are therefore very special.
Mollusks (ToL: Mollusca<Lophotrochozoa<Bilateria<Metazoa<Eukaryota)
	Gastropods (Gastropoda) flourished in the Pennsylvanian. Two specimens of Worthenia sp. are displayed.
	Bivalves (Bivalvia): Mobile bivalves flourished on the muddy sea floors, displacing the sedentary brachiopods. A clump of fossilized mussels, Myalina perattenuata, are displayed.
Brachiopods (ToL: Brachiopoda<Lophotrochozoa<Bilateria<Metazoa<Eukaryota)
	Brachiopods were smothered on muddy bottoms, the spirifereds declined. Two brachiopod species are displayed: Dictyoclostus sp. and Linoproductus sp.
Corals (ToL: Cnidera<Metazoa<Eukaryota)
	Cnidarians (corals): Both small (Lophophyllum profundum) and large (Caninia torquia) horn corals are in the collection.
Pennsylvanian Plant Fossils
Vascular Plants (ToL: Embryophytes [land plants] <Green Plants<Eukaryota)
	Filocopsida (ferns and their relatives) were common in the coal swamps of this period. Fern leaves, such as those of Alethopteris seilii, looked much as they do today. Tree ferns (represented by a Pecopteris sp. leaf) grew to 50 ft.
	Seed ferns had leaves similar to the true ferns, but differed in having pollinated seeds. They thus avoided the separate sexual plants and the dependence on standing water for reproduction. They may have been the ancestors of the flowering plants. Fossils in this case include: Neuropteris sp., Sphenopteris artemisaefolioides(positive and negative impressions), and Neuropteris sp.
	Equisetophyta (Sphenophyta, rushs), similar to todays horsetail rushes, but often much larger (up to 30'), were both diverse and common. A number of species of Scouring rushes are represented:Annularia longifolia (positive and negative impressions), Annularia stellata, and a scouring rush trunk (Calamites sp.). There is also a Sphenophyllum emarginatum (positive and negative impressions).
	Lycopodiophyta or Lycopods (primitive trees) were among the earliest trees, reaching heights of up to 100'. The scale tree (Lepidodendron) specimen shows the surface patterns characteristic of these organisms

The engravings are from Dana, James D. (1870) Manual of Geology, Le Conte, Joseph (1898) A Compend of Geology, Louis Pirson and Charles Schuchert, A Text-Book of Geology. (1920), or McMurrich (1894) Invertebrate Morphology.

Case Index

Life Through Time Mural

Geological Timeline

Last modified 29 January 2007 | ©1998, HSU NHM