Turtle pleural bone? Tiny Mosasaur Bones?

[Planko]

All were found NSR today. I am really guessing on both. I am going turtle pleural bone just from the pictures I have seen. Other than a really small mosasaur I am clueless on the verts.

[pachy-pleuro-whatnot-odon]

Wow! I know this is an old one, but am surprised nobody has responded to this, seeing as much of it can easily be answered, in my opinion.

 

The first photograph, for example, shows a clear example of a mosasaur terminal caudal vertebra on the left, and with the second piece likely being a warn halved/split vertebra.

(source)

 

The third piece definitely looks like a turtle pleural bone. For comparison, have a look at this thread and, in particular, the below pleural bones from @Al Dente's collection illustrated in it: