Belemnitella americana cepholopod from New Jersey

One of the most common fossils found in the Cretaceous sediments of New Jersey and Delaware are the cigar colored and shaped guards (rostra) of Belemnitella americana. They are called guards but were actually internal supports/skeletons of the animal. B.americana belonged to a group of squid like creatures called Belemnites that have relatives in the modern cuttlefish. When they existed during the Jurassic and Cretaceous they were prolific and sometimes formed massive shoals with their skeletons. Belemnitella americana is the state fossil of Delaware.

Here is an example of a nearly complete specimen that I found. It was broken into two pieces that I glued back together. The next few pictures show the guard rotated every 90 degrees towards the camera.

This is the very end of the rostrum and should narrow down to a tip but that is missing from this specimen.

Here is a view of the living chamber where the phragmocone would have been and the internal organs of the animal were stored.

Another view to show you the depth of the chamber.

Speaking of the phragmocone, below is a specimen that retains this feature. The phragmocone was the equivalent of the ammonites curled shell. Each band represents a period of growth and if one looked carefully enough at the very tip there would be a protoconch. The guard was a skeleton that was deposited around the phragmocone rather than a shell like in ammonites.

Some of the guards were left exposed on the sea floor for long enough time to be colonized by other animals. Here a bryozoan colony grew on a guard and then later had some Spirorbis worms build their homes on top of them.

All specimens come from the Navisink and Mt. Laurel formations of New Jersey in Monmouth County, NJ. The formations record the very end of the Cretaceous in the Campanian and Maastrichtian stages.

These are the first American Belemnites I've shown with prior posts showing specimens from Poland and Sweden.

Ostrea falcata pelecypod from New Jersey

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.

Left valve

Anterior

Left profile

Posterior

Right profile

Right valve

Here is a second specimen: Left valve

Anterior

Left profile

Posterior

Right profile

Right valve... Note the bore hole made by a predatory snail.

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.

Left valve

Right valve

Anterior

Left profile

Posterior

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.

Evidence of the boring sponge Cliona cretacica from the Cretaceous of Delaware

Below is a specimen which is interesting due to the evidence of epibonts. It's a piece from an large oyster shell that was found in Delaware along the C&D canal spoil piles (Cretaceous aged sediments dredged from the canal in the 1970's). Upon and within the shell is evidence of multiple generations of the boring sponge Cliona cretacica along with some bryozoan colonies. There is even evidence that the bryozoan colony skeletons themselves may have been later victims of the sponge.

A view of the whole specimen shows the holes in the shell that are from the boring sponge and the bryozoan colonies.

Close up of the bryozoan fossils....

... and the traces left by the sponge.

Cliona didn't parasitize or kill the Oyster who originally made the shell nor the bryozoans. It merely scraped out a home for itself within the calcareous remains and possibly utilized the calcium for it's own skeleton. Because the sponges bodies quickly fell apart after death we don't have many direct fossils of them. Instead we are left to interpret the evidence they left behind of how they impacted their environment. This is also good evidence that some oyster shells laid on the surface of the seafloor for long enough to provide a habitat for other animals.

Neithea quincostata & Liopistha protexta pelecypod steinkerns from Delaware

Here are a couple more steinkerns from the Cretaceous sediments of Delaware. As I mentioned in previous posts, these are clay casts of the interior space of Pelecypod shells.

This is a cast from a Neithia shell and could be Neithea quincostata

Right valve

Left valve

Anteiror

Left profile

Posterior

Right profile

This cast is very likely Liopistha protexta

Right valve

Left valve

Anterior

Right profile

Posterior

Left profile

Both specimens come from the C and D canal in Delaware and were collected from spoil piles left over from dredging efforts. Their age is late Cretaceous (Campanian to Maastrichtian stages).

Thanks to John's site Fossils of New Jersey for helping me ID these fossils.

Another sites with an extensive collection of fossils from the canal is Dr. Fossil's site about the "Deep Cut"

Cardium sp. pelecypod steinkerns from Delaware

Much of the mollusk fauna preserved in the unconsolidated Cretaceous aged sediments of New Jersey and Delaware is found as steinkerns or internal casts of the original shells. The original shell material often has been dissolved away by ground water or otherwise weathered such that it is no longer present. It makes things a bit more difficult when trying to ID what you found down to the species level.

Here is a specimen of a steinkern from a Cardium type shell. It is a little beat up along the sides but it could be a Cardium spillmani. Notice all the indentations that are preserved in the cast. I interpret these as molds of various worm or bryozoa fauna that colonize or parasitize old shells.

Left valve

Left profile

Right valve

Right profile

Anterior

Posterior

Another specimen that likely fits in the Cardium genus and could be a Granocardium tenuistriatum is shown below. It is smaller than the above specimen and in better shape.

Right valve

Left valve

Anterior

Left profile

Posterior

Right profile

Both specimens come from the C and D canal in Delaware but I can't say for sure what formation. They were collected from spoil piles left over from the dredging of the canal which mixed the sediment from several formations together. What I do know is that they are from the late Cretaceous (Campanian stage to Masstrichtian stage). I tried to ID the specimens from Bulletin 61, "Cretaceous Fossils of New Jersey"  published by the New Jersey Geological Survey, 1958. There are two volumes of Bulletin 61: Part 1 and Part 2 .