Southern Maryland Miocene Bones

[PHFossilGuy]

On the last two trips my son and I have made down to one of our favorite spots near Saint Leonard, MD we found these specimens. I've some guesses about what they are but would appreciate some corroboration. All were found along the shore of the Chesapeake Bay in southern Maryland in the Choptank formation.

[PHFossilGuy]

We're thinking this bone, which is about 3.5 cm across at the base and about 1 cm across at the tip and about 4.5 cm from base to tip, might be a cetacean neural spine vertebra?

[PHFossilGuy]

We're thinking this might be a cetacean inner ear bone? It is about 2 cm across at its widest point.

[PHFossilGuy]

Might this be a bony fish preopercle? It is about 6.5 cm tip to base and about 4 cm at its widest point.

[PHFossilGuy]

For this, we were thinking perhaps a partial thecachampsa femur? It is about 20.5 cm long about 6.5 cm at its widest point.

[PHFossilGuy]

This one truly has us stumped. We're thinking a vertebra of some kind, but no idea of type of animal or if it even is a vertebra. It is about 5.5 cm from tip to base and about 2.5 cm at the widest point.

[ClearLake]

First one looks similar to a reptile coracoid bone to me (part of the front limb "shoulder" structure).  Or maybe part of the pelvic girdle too, I'd have to look more closely at some examples.

 

Second one certainly looks like a fish bone.

Edited January 26 by ClearLake

[FossilDAWG]

Definitely fish for the "preopercular", but I don't know what one off the top of my head.

 

@Boesse, @MarcoSr, @digit, @Harry Pristis, or @Shellseeker, amongst others, might be able to provide more useful commentary.

 

Don

[hemipristis]

3 hours ago, PHFossilGuy said:

Might this be a bony fish preopercle? It is about 6.5 cm tip to base and about 4 cm at its widest point.

Concur

[Shellseeker]

6 hours ago, PHFossilGuy said:

We're thinking this might be a cetacean inner ear bone? It is about 2 cm across at its widest point.

I have seen and found a large number of Whale and Dolphin ear bones, both Tympanic Bullas and Periotics,  sometimes referred to as Petrosals, 

2 cm would more likely be in the dolphin size rather than Whale. It is something else.. 

I can not rule out Fossil Sirenia,  since I am much less knowledgeable on those ear bones.

[Boesse]

On 1/26/2024 at 2:29 PM, PHFossilGuy said:

We're thinking this might be a cetacean inner ear bone? It is about 2 cm across at its widest point.

I am 100% confident that this is not an earbone fragment of anything and about 90% fragment this is part of a walnut!