Up for viewing today are a couple of Ostrea falcata fossil oysters from the Cretaceous of New Jersey. These are uncommon fossils that I found in the Navesink formation exposed along Big Brook in Monmouth County, NJ. There is a layer where these are found in more abundance that could represent a storm deposit or possibly a calm period which allowed colonization of the seafloor. This species is very similar looking to the more common Ostrea mesenterica (that I'll post about later) but O. falcata has obvious surface ornamentation.
Here is a second specimen: Left valve
I also have a steinkern of a much larger specimen of O. falcata that came from the C&D canal in Delaware. I purchased it at a show put on by the Delaware Mineralogical Society.
All the above specimens come from the Masstrichtian stage of the Cretaceous when New Jersey and Delaware were submerged under the Atlantic Ocean and Philadelphia was beachfront property.