Pterosaur wing bone from the Hell Creek Formation?

[talon22]

Hi,

 

Was just checking our favourite auction site for fossils and i came across this. It is interesting because the seller has it listed as a Pteranodon wing bone from the Hell Creek Formation (in Montana), yet this seems odd because Pteranodon has not been described from the Hell Creek Formation and existed at a different time (around 85 mya), so this makes me skeptical whether this bone is pterosaur or possibly from something else like a theropod (the bone is 9 inches long). Any opinions if it is pterosaur or not, the pictures are a bit hard to tell by. Thanks.

 

 

[Tidgy's Dad]

It looks more like a theropod in my limited experience. 

Where it's broken it doesn't look hollow enough for a ptersosaur either. 

[caldigger]

What is raising a red flag for me is the matrix that is attached to the bone looks a different color than the block it is resting on.

[talon22]

Yeah i agree that it is probably more likely to be theropod, because from what i understand, pterosaur remains from the hell creek are extremely rare and are from Azhdarchids not Pteranodontids. Not sure about the matrix, the seller does say it is unprepped.

[Haravex]

Ok this is the first thing I ask when looking at any type of these fossils what can it not be?

Well first we look at process of elimination its for sure too elongated to be a vertebrae we can all agree on that. its not any skull element that I have ever seen on any animal. so this leaves the following possibilities from a limited anatomical knowledge. rib, limb bone or chevron.

second stage further analysis of the anatomy it appears to be one solid component no where at either end visible suggest that a portion of the bone has been broken? do we agree? if so this eliminates chevron but does not eliminate rib bones until you consider that most small dinosaurs have a certain curvature to the rib elements only on larger theropods and sauropods do we get any degree of straight rib bones especially at 9 inches i'm ruling out cervical rib bone elements.

third stage - red for me indicates areas or natural grown such as plant mater growing in between cracks blue indicates evidence for thickness also notice the upper section of this bone is mostly collapsed giving further evidence the bone is hollow.

final stage given the length and the the evidence to support this bone is hollow we are left with a limited number of options these being 

limb bone from a small theropod limb bone from a pterosaur

Theropod possibilities ulna, radius, metatarsal.

Azhdarchid possibility metacarpal iv, ulna fibula