B1. ORIGINAL SHELL MATERIAL
Fossilization often involves post-mortem chemical alteration of skeletal material resulting from corrosive fluids percolating through the sediments entombing the fossil remains. Sometimes this alteration is not very extensive, however, and the original shell is preserved with little modification. This is the case with this extinct Cretaceous (70 mya) oyster Exogyra punctata from Middletown , NJ .
B1.1 Using acid, determine the mineral composition of the fossilized shell of Exogyra.
B1.2 Now test the shell of the modem edible oyster Crassostrea virginica with acid. What do your results imply about the magnitude of evolutionary change in shell mineral composition in oysters.
Department of Geology
Brooklyn College
Brooklyn, NY 11210