Peace River Femur

[minnbuckeye]

I had the privilege of a day on the water with JCBShark and Shellseeker. When I found this bone, they both thought modern. It sounds fossil like when I hit it against something hard but the flame test showed that at best it is old, in that a slight but definite smell permeated the air when put against a flame. Whether a "young" fossil or modern, I still want to try and ID this. The prominent ball just stands out to me as being different. The lesser  trochanter is fractured off. 

 

 

 

 

[Mark Kmiecik]

Rabbit? I'm no expert though, so wait for others as well. The little spike is what's left of a blade-shaped process that is broken off.

[minnbuckeye]

 

 

 Looks like the femoral neck is quite thick in the rabbit so I am leaning away from this ID. Though I do NOT know bone variations between most species. Photo from 

Endoskeleton of Rabbit (With Diagram) | Vertebrates | Chordata | Zoology

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[Mark Kmiecik]

5 minutes ago, minnbuckeye said:

 

 

 Looks like the femoral neck is quite thick in the rabbit so I am leaning away from this ID. Though I do NOT know bone variations between most species. Photo from 

Endoskeleton of Rabbit (With Diagram) | Vertebrates | Chordata | Zoology

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You're right. I googled rabbit and see what you mean. I was judging by the approximate length mostly.

[minnbuckeye]

Squirrel femurs seem to match this closely. Maybe I am getting close! But the bone thickness (thin) concerns me.

[caldigger]

Your one pic shows it being quite thin walled and hollow. Maybe that will eliminate some contestants.

[ClearLake]

It is not rabbit, they have very little “neck” on the ball joint.  Based on pictures in Gilbert’s Mammalian Osteology, it looks like a squirrel.  I don’t have a comparison of a grey squirrel vs a fox squirrel, but I’ll see if I can find one. See the attached picture from the book (upper middle). 

[Spoons]

Is there no possibility of this being a bird bone since its hollow? Please correct me if I'm wrong, I want to learn.

[ClearLake]

Yes, but being hollow does not rule out mammals.  Most mammal long bones have a somewhat hollow core (not air filled like birds, but they are not filled with solid bone).  They are filled with marrow, etc and after death, that sort of material is the first to go, leaving a hollow bone.

[ClearLake]

@Spoons, I should have also added, that I went through my reference on bird bones and could not find any that were a match for the one in question. There are several features that would point to it being a mammal bone. I also should have said “many” mammal long bones are somewhat hollow as I don’t really know that it is “most”. But the point is, I think the bone in question is a good match for a squirrel femur, hollowness and all.  

[Spoons]

2 hours ago, ClearLake said:

Yes, but being hollow does not rule out mammals.  Most mammal long bones have a somewhat hollow core (not air filled like birds, but they are not filled with solid bone).  They are filled with marrow, etc and after death, that sort of material is the first to go, leaving a hollow bone.

That makes total sense, especially being such a gracile creature as a squirrel we wouldn’t expect to see the same bone densities as larger mammals, thus explaining why this specimen seems so thin walled.

 

Thank you for the quick response.

-Nick

[minnbuckeye]

16 hours ago, Spoons said:

Is there no possibility of this being a bird bone since its hollow

 

@Auspex

[Auspex]

23 hours ago, Spoons said:

Is there no possibility of this being a bird bone since its hollow? Please correct me if I'm wrong, I want to learn.

While the walls are thin enough to suggest birdliness , the articulation structures are wrong. For most avian long bones, think soda-straw-thin walls, or close to it proportionally.

[Spoons]

8 hours ago, minnbuckeye said:

 

@Auspex

Thank you for doing that.

 

47 minutes ago, Auspex said:

While the walls are thin enough to suggest birdliness , the articulation structures are wrong. For most avian long bones, think soda-straw-thin walls, or close to it proportionally.

Could you elaborate on what you mean by articulation structures? Do you mean the head of the femur that articulated with the acetabulum?

If so, I see what your saying, the head in most mammals seems to be more pronounced and well defined than in birds and reptiles, here’s a picture that I saw on the google that I think illustrates what I’m talking about. It’s from Boneclones.com

 

Heres the key: 

1-Horse femur, 2-Sabertooth Cat femur, 3-Human Adult Female Femur, 4-Komodo Femur, 5-Harpy Eagle Femur, 6-Kiwi Femur, 7-Platypus Femur, 8-Spider Monkey Femur, 9-Rhesus Macaque Femur, 10-Vervet femur, 11-Goliath Frog Femur, 12-Flying Lemur Femur.