Tennessee


 * =** Tennessee: // Pterotrigonia thoracica //**=


 * ** Description: **// Pterotrigonia thoracica // (or “Ptero”) is an extinct species of bivalve. A bivalve is a mollusk that has two symmetrical shells (oysters, clams, mussels.) Ptero has a wedge-shaped shell with prominent ribs. It was a small mollusk that inhabited the soft clay sands of shallow prehistoric seas. It lived with its smaller end burrowed into the sand and its posterior up. The shell interior sometimes enclosed a pearl.


 * **// Pterotrigonia thoracica //**




 * ** Time Existed: ** Ptero lived about 65 to 70 million years ago in the Maastrichtian Age of the late Cretaceous Period, when a shallow sea encroached upon Tennessee. Coon Creek during the Maastrichtian Age was semi-tropical and 100 feet deep. Severe tropical storms were frequent. To the east, it was marshy and filled with bluffs, sluggish rivers, and heavy forests.


 * ** Preservation: ** Ptero was preserved in a deposit of sedimentary marl that formed about 70 million years ago in Coon Creek.


 * ** Who Found the Fossil and Why Is It The State Fossil? ** At the University of Tennessee at Martin, the GeoClub campaigned to have // Pterotrigonia thoracica // (or “Ptero”) as the official state fossil in 1996. It was named State Fossil in 1998 with the help of professor Michael A. Gibson and State Senator Roy Herron. E.C.N. van Hoepen found it in 1929 in the Coon Creek Formation in western Tennessee.


 * ** Sources: **

World Trade Press. (2006). State fossil of Tennessee. Retrieved from xxxx http://www.atoztheusa.com/states2.asp?ni=12&cid=45

Memphis Archaeological and Geological Society. (2003, July). Coon creek fossils. //Rockhound xxxx news, 49//, 1-5.