Hi all, here are a few teeth I've found in sifting the matrix from the Martin, Marietta Cement plant near Midlothian Texas. It is the contact between the Austin chalk and Eagleford shale formations. Aprox. 90 million years ago, when the ocean was void of oxygen and everything died. Void because we find large amounts of Iron Pyrite everywhere there and it only forms in an oxygen depleted environment.
The teeth are Ptychodus whipplei, and Cretolamna appendiculata.
TroyB