Niobrara Chalk Vertebra (Cretaceous of Kansas)

[ziggycardon]

Hi everyone, 

I just ordered this beautiful vertebra found in the Niobrara Chalk of Kansas (Cretaceous, 87 - 82 mya) for quite a bargain. 
Unfortunalty I don't have any precise location as where it was found, for that I am going to contact the seller.

The vertebra was listed as being Mosasaur which it could very well be, but since it is a little bit distorted I am not quite sure, especially since many other critters can be found in the Niobrara Chalk. 
So I was hoping on the expertise of some of our members here who have more knowledge of Cretaceous verts and of Kansas fossils. 
 

@KansasFossilHunter @Troodon @LordTrilobite @pachy-pleuro-whatnot-odon @The Amateur Paleontologist you guys might be able to shed some more light on the piece?
Thank you in advance! 

Topic might be more usefull with some pics, so here they are. 

 

[LordTrilobite]

Pretty sure those prezygapophyses with the little "grabby mittens" are typical of some mosasaurs. Others might be able to elaborate more on this.

[pachy-pleuro-whatnot-odon]

Bugger! I've seen this one come up online yesterday and had actually planned on buying the block with the two vertebrae in it... Then kids came in between and after that it slipped my mind... Until now! I don't seem to be very lucky with the Kansas vertebrae, as this is the fifth one that has slipped between my fingers this month. I've really been looking to add a nice - preferably matrix-free - specimen to my collection, but something always seems to go wrong.

 

Anyway, other than that this does look mosasaurian to me and that the neural arch has likely been pushed into a more horizontal position than it would've had in life, I'm not too sure I can help you, as I haven't dabbled in the identification of mosasaur vertebrae too much yet. There have been suggestions that the wide, cup-shaped oval shape of the vertebral centrum is indicative of plioplatecarpine mosasaurs (see posts below), but have equally seen round vertebrae advertised as platecarpine, as well as apparently similarly shaped ones as tylosaurine.

 

 

Compare the above examples with the below, however, which is a Moroccan specimen, and you might argue that the Moroccan specimen is equally a platecarpine vertebra (thus, Gavialimimus almaghribensis).

 

 

However, while I have little experience in these matters as of yet, I believe vertebral shape in mosasaurs may be less dependent on species and genus as it would be on the position along the spinal column, much as is the case in ichthyosaurs. In this case, the flat, widened vertebrae are cervicals, round ones caudals and triangular ones (like the one below, unfortunately source unknown) dorsals.

 

 

However, since your specimen appears to be a cervical anyway, may be the below image (taken at the Museum voor Natuurwetenschappen in Brussels) may form a useful reference:

 

A. Plioplatecarpus houzeaui, B. Mosasaurus lemonnieri, C. Mosasaurus hoffmanni

 

And, if all else fails, I'd recommend asking on the Dutch forum. There are still quite a number of knowledgeable people on there as well, even if they would likely specialised in different mosasaur species.

[ziggycardon]

Thank you for the fast and helpful replies! 
I am glad my feeling was right about this vertebra this time and I made the call to buy it. 
I really look forward to recieve it alongside with another cervical mosasaur vert I also ordered today which comes from the North Sulphur River. 

I know that it's hard to ID the vertebrae on a genus level and I didn't really expect that to already happen, I am just glad to know that it is indeed Mosasaurian  

When it arrives I'll shall make some more and better pictures, but since it comes from overseas that might take a while.