Dinosaur Vertebra?

[justretired]

Another fossil from my thrift store find. The information tag said, “1950’s collection fossils and rocks-in matrix. Mosasaur vertebrae- 300 million years old. Found in South Dakota.”  Is this true? What does “in matrix” mean?

 

 

[Brevicollis]

Its definetly a bone. I cant identify it tho. But its possible for it beeing Mosasaur, because they're known from South Dakota. Is it still known, in which formation it was found ? It could help to further ID it.

In Matrix means, that its still in surrounding rock embedded or partially embedded. The age seems very wrong, because Mosasaurs first appeared in the Cenomanium (100mio. Years ago) according to Wikipedia.

Edited April 24 by Brevicollis

[Tidgy's Dad]

And just to clarify; a mosasaur is not a type of dinosaur. Mosasaurs are squamates, thus belonging to the same order as lizards and snakes. So giant marine lizards if you like.

Mosasaurs can be commonly found in South Dakota, so that bit could be right.

Mosasaur vertebrae do have one concave and one convex side, so this also fits the specimen.

[Fossildude19]

Definitely bone, looks to have some matrix adhering to the fossil, and definitely NOT 300 million years old. 
If from the Pierre Shale, it would be Campanian (Late Cretaceous) in Age. The Campanian spans the time from 83.6 (± 0.2) to 72.1 (± 0.2) million years ago.

[rocket]

something to check, Mosasaurs from Pierre shale

 

The Mosasaurus and Other Mosasaurs Collection (oceansofkansas.com)

 

Vertebrae looks like Mosasaur-type, but might be not. 

 

[justretired]

Thank you so much, everyone!  You’ve all been amazing!  After I get the information on all these fossils, I’m going to do a presentation to the 4th and 5th graders I used to teach. They will be so excited!  Thanks for the age correction, the website with more information, and the meaning of “in matrix.” I’m learning a lot!

[jpc]

This certainly looks like a mosasaur vertebra.  But rather than show us two or three photos from the same angle, can we see it form a few other angles?

 

[justretired]

At someone’s request, I tried to take better pictures. I hope these are more helpful. I’m new at this and so excited. If I’m doing anything else wrong just let me know. 

[pachy-pleuro-whatnot-odon]

The bone is quite a jumble. But no doubt about it, this is indeed a mosasaur vertebra - and quite a decent sized one at that! Could be a lumbar to judge by shape and length...

[jpc]

Yes, mosasaur vert ... but it does not look like anything I have seen from South Dakota.  That doesn't mean it isn't from there, it just looks different.  I am talking about the rock and the preservation, not the bone.