Early rhino skulls

[PalaeoArt]

I'm looking for some help from any expert of the White River Badlands to help with the ID of these two partial fossils skulls I'm working on prepping. I purchased both of these at auction from old collections so sadly I don't know the locations they were collected, but I'm confident that they're White River specimens from the Oligocene. I'm pretty sure that both of these are examples of early rhinos like Subhyracodon and Hyracodon but I'd love some help with ID if possible. The first skull (first 3 photos with the darker teeth) is the largest at roughly 25cm across (although this is partial skull only) and has beautifully preserved teeth (albeit a very fragmented skull). The second skull has lost a few teeth (second 3 photos with more orange colored teeth) but the skull is better preserved - roughly 22cm across - this one as a much shorter snout. Both skulls have a reverse side hidden by matrix which I'm yet to remove. I'm hoping that the preservation is better on the other side.

Looking at these closely, I believe these are two different species as the dentition looks different. I'd welcome anyone's thoughts.

[fossilized6s]

@jpc

 

Nice pieces

[Shellseeker]

I love  those teeth and you have FULL roots.  Congratulations on an excellent purchase!!!

Can not help on the ID .. I only know a little about Florida Miocene Rhinos!!!!

[Darko]

Nice finds !

[RJB]

Wow!  Those are cool.  I cant help you but nice to look at these things!!!

 

RB

[hxmendoza]

Both are Rhinocerotidae.

The first skull with the black teeth appears to be Subhyracodon. Probably Subhyracodon occidentalis.

The second one, with the brown teeth, is Hyracodon. Very likely Hyracodon nebrascensis.

Both are out of the Oligocene period, 25 MYA

[sharko69]

Wow! Those are beautiful. Thank you for sharing.

[PalaeoArt]

13 hours ago, hxmendoza said:

Both are Rhinocerotidae.

The first skull with the black teeth appears to be Subhyracodon. Probably Subhyracodon occidentalis.

The second one, with the brown teeth, is Hyracodon. Very likely Hyracodon nebrascensis.

Both are out of the Oligocene period, 25 MYA

Thanks @hxmendoza for the positive ID on both of these. Were there certain features which made these easy for you to identify? Thanks again for your help

[Fossils?]

Beautiful, nice finds

[jpc]

I only now saw this.... is 25cm "across"... what does "across" mean?  To me that means from one eye hole to another.  

Both are certainly rhinos.  And I think hxmendosa is correct on the genera.  

[PalaeoArt]

5 minutes ago, jpc said:

I only now saw this.... is 25cm "across"... what does "across" mean?  To me that means from one eye hole to another.  

Both are certainly rhinos.  And I think hxmendosa is correct on the genera.  

That's a fair question @jpc. The "across" reference is really the length but as both of these fossils are either missing the rear of the skull or the premaxilla, therefore I couldn't get any degree of accurate skull length estimate.  So the across is really a reference to the length of the partial exposed bones of the skull (not that scientific I grant you). The 3rd picture on each however has a 10cm measurement guide.