Partial Femur Identification (hadrosaur?)

[rkfrace]

Hello all.  A decade ago, before I started keeping proper track of the specimens I own, I purchased a partial femur specimen (for context, it was fairly cheap, less than $150 I think).  Anyway, I 'think' that it was from a Hadrosaur, but I don't think the seller knew for sure -- and I know for sure that I don't know for sure!   Anyway, I don't recall the formation (I'm going to guess Judith River, but that's based on very little).   

 

Any, if anyone is able to readily identify/confirm that the partial femur is from a hadrosaur, or from something else, I'd deeply appreciate it.   The specimen is highly mineralized and heavy; please see photos.  Thanks!   

[TyBoy]

Looks like a mammal bone

[rkfrace]

5 hours ago, TyBoy said:

Looks like a mammal bone

Thank you, but the problem is that the bone is densely mineralized in a way that no mammal bone mineralizes (so far as I am aware, since any mammal bone this big would be no older than the Oligocene).  It's heavier than a bowling ball; I could hit the core of the bone with a chisel (see the third image from the top) and it would barely notice (also,  I have various Titanothere bones, none of which are at all comparable).  

[jpc]

Why do you say mammal bones do not mineralize?  Almost all the mammals I collect out here are well mineralized.  

TyBoy is onto something. This is the distal end of a titanothere humerus.  I am 90% sure.   Late Eocene on age.  Likely from the White Rver Fm of SD, NE or WY.  And yes there are big mammals in the pre-Oligocene.  It was thought that titanotheres were early Oligocene, but about 20 years ago, the Eocene/Oligocene boder wasnmoved and now titanotheres are late Eocene.  I should specify, the last (huge) titanotheres are late Eocene,  There are less famous smaller ones that go back to early Eocene.  There are also Uintatheres in the mid Eocene that got pretty darn big.  

 

Nice chunk of bone, by the way. 

[Guns]

i have no idea what this is, sorry but it is a very nice looking bone section! 

[rkfrace]

12 hours ago, jpc said:

Why do you say mammal bones do not mineralize?  Almost all the mammals I collect out here are well mineralized.  

TyBoy is onto something. This is the distal end of a titanothere humerus.  I am 90% sure.   Late Eocene on age.  Likely from the White Rver Fm of SD, NE or WY.  And yes there are big mammals in the pre-Oligocene.  It was thought that titanotheres were early Oligocene, but about 20 years ago, the Eocene/Oligocene boder wasnmoved and now titanotheres are late Eocene.  I should specify, the last (huge) titanotheres are late Eocene,  There are less famous smaller ones that go back to early Eocene.  There are also Uintatheres in the mid Eocene that got pretty darn big.  

 

Nice chunk of bone, by the way. 

 

Hi jpc.  I didn't say that mammal bones do not mineralize; I only said that I have never encountered Oligocene bones mineralize in this particular way or to this degree. 

 

Your information about pre-Oligocene titanotheres and uintatheres, however, was very helpful, and it would certainly help to explain the distinctive nature of the specimen.  (Granted, it's also quite possible that Oligocene specimen cores are also capable of this type of mineralization - where the marrow structure visible in cross-section looks more like, and has the hardness of, the middle of a common Jurassic coprolite in cross section; I just haven't personally encountered it as a collector.  I've been collecting for 15 years, but I'm based on the East Coast; I've pulled back on buying large Oligocene specimens due to how frequently they've arrived damaged - owing primarily to their relatively fragile state if not stabilized. The local postal workers have some notable anger-management issues, though I respect the work they do).    

 

Thanks for your reply/insight and compliment.  (And GUNS: thanks for the compliment, too!)  

[Earendil]

13 hours ago, jpc said:

Why do you say mammal bones do not mineralize?  Almost all the mammals I collect out here are well mineralized.  

TyBoy is onto something. This is the distal end of a titanothere humerus.  I am 90% sure.   Late Eocene on age.  Likely from the White Rver Fm of SD, NE or WY.  And yes there are big mammals in the pre-Oligocene.  It was thought that titanotheres were early Oligocene, but about 20 years ago, the Eocene/Oligocene boder wasnmoved and now titanotheres are late Eocene.  I should specify, the last (huge) titanotheres are late Eocene,  There are less famous smaller ones that go back to early Eocene.  There are also Uintatheres in the mid Eocene that got pretty darn big.  

 

Nice chunk of bone, by the way. 

I think jpc is right, here is a similar specimen belonging to a titanothere. (complete humerus)

[jpc]

3 hours ago, rkfrace said:

 

Hi jpc.  I didn't say that mammal bones do not mineralize; I only said that I have never encountered Oligocene bones mineralize in this particular way or to this degree. 

 

Your information about pre-Oligocene titanotheres and uintatheres, however, was very helpful, and it would certainly help to explain the distinctive nature of the specimen.  (Granted, it's also quite possible that Oligocene specimen cores are also capable of this type of mineralization - where the marrow structure visible in cross-section looks more like, and has the hardness of, the middle of a common Jurassic coprolite in cross section; I just haven't personally encountered it as a collector.  I've been collecting for 15 years, but I'm based on the East Coast; I've pulled back on buying large Oligocene specimens due to how frequently they've arrived damaged - owing primarily to their relatively fragile state if not stabilized. The local postal workers have some notable anger-management issues, though I respect the work they do).    

 

Thanks for your reply/insight and compliment.  (And GUNS: thanks for the compliment, too!)  

Hi rkfrace-

This thing is fairly typical in preservation for the lower White River Fm, where large titanotheres are found.  But having said that, there is quite a variety of preservations in these beds.  I have no idea what "common Jurassic coprolites" you are talking about.

 

But beyond the preservation, here is a ipicture of the humerus of Brontops, the large White river titanothere.  (I happen to have Osborn's 1929 titanothere monograph right here as I am currently trying to ID a lower jaw I am working on from the middle Eocene).  So, from page 609...

 

 

Your bone is the distal end (elbow joint) seen just above the "G3"  notice the articular surface which itself is the smooth part exactly above "G3".  That is where the radius and ulna hinge with the humerus.  That part is plainly visible in most of your pix.  In the drawing, the part sticking out sideways from this the the right and up a wee bit is fairly diagnostic for a late Eocene titanothere.  It is basically a large flat muscle attachment point.  That is the part you are holding in the third photo.  

 

The round divot in your second photo, above the 5 in your tape measure is the notch that a process (sticky out thing) on the ulna fits into when this guy's front leg was straightened out.  This divot alone tells us this is a mammal.  Hadrosaurs do not have this divot.  No dinosaur does because they don't have that process on the ulna. 

 

I hope this helps clarify things.  If not, feel free to ask.