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Theropod Femur ID


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Hello All, This is for @Troodon and all other theropod experts. I recently acquired this Femur that is 20 inches and reportedly T rex. I have seen similarly sized nano femurs and this one is more robust and thicker. Polling the community to see it you all think this is Rex. Also, What is the material in the center? It is dark brown and runs the entire length of the bone (the cross section pic has white adhesive on the material in question). Marrow? Matrix? I have sent these pics to Pete Larson and he is MIA (no response yet). Hoping you all can end my debate. Thanks

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  • Fossildude19 changed the title to Theropod Femur ID

Very nice femur but dont get a Trex vibe with your specimen.   Looking for the fourth trochanter t4 in the photo.   Do you have a photo like your first one of the other side?   The shaft of your specimen looks to round and straight.  

Photo of Sue 

Screenshot_20191002-110851.thumb.png.98f809e9a8d981cecfd7c0a922929297.png

 

Here is a photo of a Nanotyrannus specimen posted a while back by member Susan from PA and identified by Neil Larsen.  I also dont believe it fits yours but need to see the proximal end of other side. Pete is a good source to help identify yours.  I also tried to get a hold of him but no luck might be in the field its that time of the year. 

 

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@Troodon - This was found at upper Hell Creek, I think Ft Peck. Apparently in an area w other Rex stuff. At 20 inches, it certainly was a juvenile. It is a theropod, correct? Were there any else but Nano and Rex at that time? What are your thoughts about the center material? Marrow? Thank you in advance

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Rex is found throughout the HC as well as other theropods such as Nano, Struthiomimus and Anzu.  If the bone was found broken the center is matrix fill.  A juvie rex would still have the characteristics of an adult although there are some ontogenetic changes.  Still would like a complete photo of the other side. 

 

Here is a Struthiomimus femur has more similarities 

www.FossilEra.com-specimen-254-113408-20.jpg.666e960360b07a2cef0996f40814d5b9.jpg 

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2 hours ago, Troodon said:

Rex is found throughout the HC as well as other theropods such as Nano, Struthiomimus and Anzu.  If the bone was found broken the center is matrix fill.  A juvie rex would still have the characteristics of an adult although there are some ontogenetic changes.  Still would like a complete photo of the other side. 

 

Here is a Struthiomimus femur has more similarities 

www.FossilEra.com-specimen-254-113408-20.jpg.666e960360b07a2cef0996f40814d5b9.jpg 

Oh my goodness... I am even more confused?! Where's Pete?!! The femur is w Ed and Sandy and I have asked them to bring it to BHI. Thanks Frank. 

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  • 2 weeks later...

@Troodon Pete Larson finally got a chance to look at the femur and compared it to many of therapods at BHI (he was very interested and spent almost an hour apparently) and he has settled on Anzu wyliei. The pics are it being compared to a Bambiraptor and then the Carnegie Anzu specimen. Though mine looks similar, it is shorter and yet more robust than the Carnegie. I wonder if there was dimorphism to explain the stout appearance. We may never know...  

femur1.jpeg

femur2.jpeg

PeteAnzuCompare.jpeg

Anzu_wyliei_info.jpeg

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Great, he's got the comparative material to give you a good answer.  Did not look like a tyrannosaurid with that smooth straight shaft.  Unfortunately sellers like to put Tyrannosaur on all bones that are big.   Well its fortunate that he was able to get the bone from Ed and Sandy, they are the best.  Thanks for the update and best to check before you buy...

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8 minutes ago, Troodon said:

Great, he's got the comparative material to give you a good answer.  Did not look like a tyrannosaurid with that smooth straight shaft.  Unfortunately sellers like to put Tyrannosaur on all bones that are big.   Well its fortunate that he was able to get the bone from Ed and Sandy, they are the best.  Thanks for the update and best to check before you buy...

Agreed. But an Anzu femur is nothing to scoff at. It is still pretty amazing. They will complete the prep work and I will post more pics when it is complete. 

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