Assorted Fossil Matrices; North Carolina, Cape Fear River.

[Korey]

Hey everybody! I'm Korey and I'm a bit new here (and to the world of paleontology in general) so I apologize if things might be a little messy. Regardless, I'll try my best in keeping things as crisp as possible. I was hoping I could have some help identifying a few fossils on the exterior of these rocks I found.

 

The following three fossil matrices were collected in a single trip along Cape Fear River in the Wilmington area. Each one contains numerous fossils of a variety of species embedded within a limestone matrix. Mineral composition was confirmed by a professor of paleontology (specialized in microfossils) at UNC Wilmington, meaning they likely originated from the Castle Hayne limestone deposit.

 

I would really appreciate some help in identifying some of the fossils found in these matrices, as while a decent number are somewhat recognizable, there are some that are completely mysterious. Specifically in matrix B and C.

 

Matrix A:

Measuring roughly 61mm in length, and 40mm in width, this is a cluster of what appears to be remnants of steinkerns and their remaining impressions. I counted over 10 individual snail shells, the exact number being a bit unclear, and a single bivalve impression. The snails appear to be some form of teribridae, while the nature of the bivalve impression is unknown.

 

The largest snail impression measured at roughly 14mm in width. Length was unfortunately not easily measured as there are seemingly no complete impressions left behind. Much of them simply stretch across the entire matrix.

The bivalve impression takes up much of it's side of the matrix, measuring at a rough 38mm.

 

Matrix B:

Measures roughly 52mm in length, and 43mm in width. This matrix is host to an intact unidentified bivalve shell, what appears to be a pair of concretions, encrusting bryozoa, and an unidentified organism.

 

The bivalve shell is roughly 25mm wide. A bryozoan colony is visible to the left of the shell's beak. You can also see the concretions top right of the shell. What species of bivalve is it?

 

Each concretion is roughly 5mm in width. The edges of the concretions appear to be encrusted by bryozoa. (It is very hard to get good pictures of this feature, I'm sorry).

 

 

The final feature of Matrix B is this unusual shape closely resembling a reverse impression of a coral cup. Measures 17mm at it's widest and 10mm at the thinnest. Seems to consist of a central undefined and weathered shape surrounded by a series of 10 striated symmetrical structures resembling the septa of a coral polyp cup. There is no other apparent evidence of similar structures within the matrix, and it seems to be entirely on it's own.

 

Matrix C:

Measuring 174mm long, and 97mm wide, this chunk of limestone has some heft to it. Contained within is the fossil of highest interest to me, what I originally thought to be petrified wood. Also present is what appears to be a eutrephoceras shell, and a single unusual ring-shaped organic artifact. This particular matrix was discovered under the water, where only a small part of it was sticking out of the submerged mud.

Jutting out of the matrix is a partly exposed branch-like structure of unknown biology. This picture depicts the anterior end of it where it appears to have been broken off, revealing the interior cross section of the branch. This structure is roughly 25mm at it's widest I had originally thought it to be petrified wood, but the paleontologist I consulted disagreed, stating that petrified wood typically looks different. It is most certainly not coral either, so perhaps it is a species of branching bryozoan?

 

Here is a side view of the branch structure, showing the deep striated appearance of it's exterior. At this point it looks almost more geological than biological, but the interior shapes tell a different story. I honestly suspect that it may have been eroded. A scant 19mm of this structure is exposed from the surrounding substrate, which I suspect might be hiding a much longer specimen.

 

Here is another branch that appears similar to the prior one, only much smaller. Measuring a mere 5mm in width at it's widest point.

 

Unlike the larger branch, the entire 25mm of this structure has been left exposed, revealing a very similar striated exterior. Could both of these have belonged to the same organism?

 

 

This little limpet-like organism was hiding in a tiny recess, merely 4mm at it's widest. Not sure what it is, really.

 

 

I appear to have forgotten to measure this one while I had my fossils out so I apologize, but this appears to be some form of coral-like structure. If you look closely you can just barely make out what appears to be a defined exterior ring nigh indistinguishable from the surrounding limestone.

 

And finally we have what appears to be Eutrephoceras or at least some other similar mollusc. It's fairly small and measures around 18mm wide from the lip to the anterior of the whorl. Only three chambers can be seen, though there might be one or two more.

 

I'm excited to see what everyone thinks of these fossils, and what they think they might be. It's a mystery that's been nagging at my mind for weeks now, and I have unfortunately yet to find answers. Please let me know if any more angles or pictures are needed, and I will try my best to provide.

[Al Dente]

This is a coral, most likely Flabellum. Everything in the photos between this coral and the nautiloid are all corals.

 

 

[Korey]

Ah wow. Looking up examples of flabellum, I can see it! Thank you for pointing me in the right direction.