Post Oak Creek Plesiosaur Bone? Mosasaur?

[jikohr]

Hi everyone!

I could really use some help identifying this one. I found it at Post Oak Creek. I included a bunch of pictures that I labeled so you all can know what I'm talking about. The microscope shots have a red scale bar that is 1 mm.

 

Here's what I know

it's Cretaceous 94-90 million years old from the Eagle Ford Group.

the bone surface is mostly weathered but still in it's original shape. except for some major weathering on the back of the left side.

It came from a large vertebrate.

The bottom is flat, the back is concave, it slopes forward to a blunt point in the front, It appears to be mostly symmetrical with the line of symmetry going front to back.

 

It looks like a distal phalange (finger tip bone) to me, but neither Mosasaurs or Plesiosaurs have a bone that looks like that to my knowledge. It honestly looks like the distal phalange of a terrestrial vertebrate to me, but, well, yeah I need another perspective before I go that route. Hey I can dream right?

 

[JohnJ]

It appears to be a highly eroded piece of mosasaur bone.  

[jikohr]

Mosasaur huh.

It's amazing what you can start to see if you stare at a bone long enough. (Which fits pretty well with that JJ quote).

Mosasaur was actually the first thing that came to my mind when I found it!

Any idea what part? The concave area in the back makes me think vertebrae.

[JohnJ]

1 hour ago, jikohr said:

Mosasaur huh.

It's amazing what you can start to see if you stare at a bone long enough. (Which fits pretty well with that JJ quote).

Mosasaur was actually the first thing that came to my mind when I found it!

Any idea what part? The concave area in the back makes me think vertebrae.

 

...It might be the remainder of a vertebra.

[jikohr]

Thanks for the help! If nothing else, it's not everyday you find a big chunk of Mosasaur bone at POC. 

 

Here's the really funny part. That day I went to North Sulphur River for the first time and found absolutely nothing. It's still early so I head to POC and then find this.