Lamellaptychus seranonis

A cool fossil that I've never found but have purchased are aptychus from Ammonites. Aptychus are hard, bilateral plates that often are associated with Ammonite remains but not always articulated with the shell. As such there has been some confusion over the years as to what they are and their purpose. Some say they are similar to the operculum found in Gastropods, others that they are parts of the jaw of the animal. In either case initially they were thought to be Pelecypods because of the bilateral symmetry.

Below are examples of an aptychus called Lamellaptychus seranonis from the Lower Cretaceous (Valanginian) rocks near Montbrun in France. This first set illustrates the bilateral symmetry very well and you can see how there could be some confusion with Pelecypods.

Another set

Sometimes the aptychus are found broken apart. When this happens it's referred to as an anaptychus.

Echinocorys sulcatus from Denmark

This fantastic 3-D echinoid fossil is from near Holtug, Denmark and is called Echinocorys sulcatus. It was sent to me by my friend Christian as part of a trade.

I like this specimen because of the seemingly exaggerated vertical shape of the fossil. Most irregular echinoids are generally shorter and more compact than Echinocorys. Perhaps the shape is due to the cold water habitat it occupied which was the same as Dendrophyllia and Dromiopsis from the previous post.

Dendrophyllia and Dromiopsis from Denmark

Dendrophyllia candelabrum is a very odd looking coral. It's known from Paleocene age rocks in Europe but is primarily found in the Danish basin and notably at exposures near Faxe, Denmark. It's a scleractinian coral but has a very dendritic growth pattern of loose, tube like shapes. They formed reef mounds in deeper, colder areas of water within the basin.

Sometimes there are decapod fossils among the coral branches. Below is a carapace from a Dromiopsis rugosa crab. This is typically how this species is found and rarely are they articulated.

The specimens shown above came from the seashore near Faxe, Denmark and are from the Paleocene (Danian stage). Thanks to Christian for sending me these specimens!

Actinocamax and Belemnellocamax cephalopods from Sweden

Finishing up my theme of fossils from the Ignaberga, Sweden area are these Belemnites.

This first specimen is Actinocamax (Goniotheutis) quadrata

The second specimen is Belemnellocamax mammillatus

For the life of me I can't tell the two species apart and am going by the labels that were sent with them. Both are from the Campanian stage of the Cretaceous and were sent to me by my friend Christian.

Salenia and Echinogalerus echinoids from Sweden

A couple more fossils from Ignaberga are some tiny echinoids. Echinogalerus peltiformis is an irregular echinoid.

Adapical surface (top)

Side profile

Adoral surface (underside or bottom)

Posterior (rear)

Anterior (front)

The other is Salenia aerolata which is a regular echinoid.

Adapical surface (top)

Side profile

Adoral surface (underside or bottom)

Both specimens come from the same quarry near Ignaberga in the providence of Scanie, Sweden. The quarry mines a layer of rock that is from the Campanian stage of the Cretaceous. Thank you to Christian for sending me these specimens.

Isocrania and Crania inarticulate brachiopods from Sweden

My friend Christian sent me a couple of inarticulate brachiopods from Sweden as part of a trade last year. Inarticulate brachiopods are considered such because they do not have a pedicle muscle with which they can anchor their shell. Instead they typically cement one valve to a hard surface, such as a rock or clam shell, leaving the other valve as a hard cap over the soft body. In order to feed they lift the cap up as there is no hinge line.

This first specimen is Isocrania egnabergensis.

The second specimen is Crania craniolaris.

Both specimens come from the same quarry near Ignaberga in the providence of Scanie, Sweden. The quarry mines a layer of rock that is from the Campanian stage of the Cretaceous. Thank you to Christian for sending me these specimens.

Protocallinassa sp. claw from the Navesink formation

As a companion piece to the Ophiomorpha nodosa burrows I posted last week, here is a partial claw from the arthropod that lived in the burrows. It's called Protocallinassa and was a ghost shrimp that lived on the seafloor scavenging for food. It's not too commonly found as the exoskeletons often fell apart in the water current after death.

I found this fossil at Big Brook near Marlboro, Monmouth County, NJ. It probably came from the Navesink formation (Cretaceous, Masstrichtian stage)which lines the banks of the creek.

Serpulid worm tubes from the Mt. Laurel formation

While searching the spoil piles of Mt. Laurel formation sand (Cretaceous, Maastrichtian stage) at the C&D canal in Delaware, I often find Pycnodonte oyster shells with worm tubes on them. These are called serpula and are considered Epibonts.

Some are weathered away and you can see just the bottom of the tubes where they attached to the shell.

Epibonts are organisms that live on the surface of another individual and are generally non parasitic. It's possible that this shell was colonized after the oyster died since they seem to only be on the convex, left side valve. Generally that valve is facing downward into the substrate upon which the animal rests. Often their sometimes coiled tubes can be confused for a gastropod shell.

Neithea from the Mt. Laurel Formation

While some internal molds of Pelecypods are tough to figure out what genera made them, this one was easy for me to identify. It's an internal mold of a Neithea shell. It is easy to recognize because of the inequal valve sizes and the strong radial ribs that are visible. It reminds me a little of a scallop and is indeed a member of the Pectinidae.

Right valve

Left Valve

Anterior

Left profile

Posterior

Right profile

I have specimens of Neithea from Texas that are of the external shell but I haven't yet got around to posting them. For now, enjoy this Google images search for Neithea.

Turritella shell mold from the Mt. Laurel Formation

In northern New Jersey, the Mt. Laurel formation underlies the Navesink formation and is a source of many different mollusk fossils generally found as molds of the internal space of the shells. If you go father south into Delaware the Navesink and Mt. Laurel are considered undifferentiated and called simply the Mt. Laurel formation. The mold below is from the Mt. Laurel formation in Delaware and was found at the C&D canal dumps. It's a Turritella sp. shell and is somewhat intact considering most found are smaller or just a small piece. It was collected many years ago when the canal was last dredged and the spoils dumped on the sides of the canal. I purchased the fossil at a local show as finding them in the field is somewhat rare these days. One of the interesting features are the sinuous tubes that seem to occur in the mold. These would have been worm tubes that formed after the snail had died and the shell was laying on the sea floor. The sediment filled in around the tubes and thus they are preserved to be seen today.

NJfossils.net has a great page that discusses the geology of the Navesink/Mt. Laurel formations as they are found in Monmouht county, NJ and references some of what I said above.
The Mt. Laurel formation is of late Cretaceous age (Maastrichtian stage).