If you came to our January meeting, you will know that we are now offering door prizes just like at IGAMS. All my spying on IGAMS meetings is proving to be very helpful! January’s door prize was part of Kansas City’s Composita layer. Composita is a genus of extinct brachiopods that were abundant during the Pennsylvanian era. Brachiopods are bottom-dwelling marine organisms that have two shells and a little fleshy “foot” called a pedicle. In a fossil brachiopod, you can see the hole where the pedicle sticks out of the shell, which is called the pedicle valve. In the upper part of the Winterset Limestone in Kansas City, there is a zone consisting almost entirely of Composita shells. See Chapter 11 of Dr. Gentile’s book for more information. Some of the shells in this specimen even had crystals inside. It was collected by David Reed somewhere in the Kansas City area, but he’s not telling exactly where.
Brachiopods have two shells, but they are not bivalves (an easy mistake to make). Bivalves are a class of mollusks, like clams, and do not have pedicles. Bivalves are symmetrical, and brachiopods are not. In fact, the bivalves may have caused the extinction of the brachiopods due to competition for food and living space.