Vertebrae ID, reptile or dinosaur?

[rifleman1961]

Found in an area overlooking the Little Missouri River basin, Clark County , Arkansas.

I have found mosasaurus vertebrae,  ball and socket in the general area where I found this one. My confusion is the intervertebral socket. Also, the overall shape is not round but flatter and with a figure 8 shape.

Please comment and if possible, what is it.

 

 

 

 

[Paleoworld-101]

This is 100% from a plesiosaur. The paired openings on the underside of the vertebra give it away. 

 

It could be polycotylid? Have a read about the types of plesiosaurs found in this deposit. 

[rifleman1961]

Thank you for your help, and I believe you are 100% correct. I took another adventure to the wash this morning, sure was chilly, and found more. The wash is both shallow, deep, wide and narrow approximately 50 yards in length. The bottom ends like a delta. Of the fossils I have found, only the largest and smallest vertebrae were found in the wash and 100% in the open. The rest were found at top grade level,.10' high bank, amongst the grass at the edge of the wash. From this point up the wash I found smallest vertebrae, and below the largest one in the wash.

From what I know the top soil layer here has oyster shells, etc, next a mixture of fine creamish to orange clay and then grey black clay.

[Mark Kmiecik]

Nice finds! Is the agate at the top from the same wash?

[rifleman1961]

No, I found it AZ a few years ago west of 194 BLM winter site north of Havasu City. It is very rare to find something like this, and only one half. I cut it and gave to the good friend who was with me. We named it "Brother" 

I used it to make the tape lie flat.

I actually have a large collection all across the great USA and it continues to grow.

Thank you all for your comments, questions and history!

Hmm, what am I?

[Fossildude19]

This looks like a piece of chert to me.

[rifleman1961]

Blue Mt Jasper, McDermitt, NV