Texas Plesiosaur Vertebra?

[GPayton]

After finding my pyritized ichthyosaur vertebra in the Grayson Formation last Friday, I decided that it was time to revisit previous exposures I had first discovered three years ago with a fresh set of eyes. I made a trip to several of those spots the following Saturday and one of the fossils I found is another vertebra. I initially wrote it off as a fish vertebra because it was so thick, then decided it wasn't flaky enough to be fish and the two holes on one side meant it must be a shark centrum, then thought maybe it could be an ichthyosaur caudal, and as of now I think it might be a plesiosaur caudal. As you can probably tell, I can be pretty indecisive! I also promise that the grooves on the face of the vertebra going towards the center weren't slips with the dental pick I was using; they were already there. 

It's about half an inch in diameter and a quarter of an inch thick.

Let me know what you all think. This thing has me stumped!

 

 

 

 

 

 

Edited April 25, 2023 by GPayton

[jikohr]

For the sake of the sheer awesomeness that it would be, I really hope I'm wrong but that looks shark to me.

 

Can someone more knowledgeable than me please say I'm wrong and it's Plesiosaur, anyone?

[Yoda]

It does look like a shark vert 

[frankh8147]

Looks shark. For comparison here is a Plesiosaur vert. I found in New Jersey

[GPayton]

It definitely does seem to match the three vertebrae to the left of this picture that the forum's own @Harry Pristis labeled as the scyliorhinoid type. My confusion at whether it was a shark or not stemmed from only ever having seen the much thinner laminiform type that don't have the two big slotted holes on one side of the rim like mine has.

 

 

"Scyliorhinoid" vertebrae are from carcharinid sharks (rather than the scyliorhinids like catsharks which leave behind miniscule vertebral centra), the only problem is there are basically no sharks from the Cretaceous in Texas that fit that category - they're all lamniforms. Does anyone that knows anything about Cretaceous sharks have any ideas?

@JohnJ @LSCHNELLE  

Edited April 26, 2023 by GPayton

[ThePhysicist]

IMO it's a bony fish vert - I've found one just like it. Shark centra have 4 holes, 2 dorsal, 2 ventral. However, I do have NTX verts that are ostensibly shark that look close to the scyliorhinoid type, so that question remains open. Can provide pics later.

[JohnJ]

33 minutes ago, ThePhysicist said:

IMO it's a bony fish vert

From what I can see, I agree.  

 

The highlighted area reminds me of the 'rims' on some fish vertebrae.   The broken areas don't scream reptile.  

[ThePhysicist]

From Sherman, TX (Turonian), each only a few mm in diameter:

 

Non-Lamniformes from this locality include several species of small Orectolobiformes so that's my best guess at the moment. There are also a couple of (rarer) species of Hybodonts, but I've no idea what their verts look like.