Radioulna

[garyc]

@GPayton recently posted a Pleistocene mammal radius that’s still waiting for a positive ID. I thought I’d try to get some info on mine as well. Mine does have the fused radius/ulna and what I learned in the latter thread is that fusion generally indicates artiodactyl. Mine seems to be in the size range of either camel or bison. Is there any way to tell the difference from the fragment I have here? @Harry Pristis

@Lorne Ledger

[GPayton]

I'm sure Harry will come along with a better explanation, but generally I've seen that camel radioulnas are much slimmer than those of bison, and the fusion area between the radius and ulna is completely closed - in bison, there are little gaps in between where the bones are fused, so that you can still make out where one bone ends and another begins. Sometimes you can see all the way through these tiny gaps, sometimes you can't. 

[JohnJ]

@garyc  Where are your photos?

[garyc]

[garyc]

5 hours ago, JohnJ said:

@garyc  Where are your photos?

That’s twice in a row I’ve forgotten my pictures!!

Here’s one more shot. So, as @GPayton was saying, there are no gaps visible between the radius and ulna. So, mine is camel?

[garyc]

6 hours ago, GPayton said:

I'm sure Harry will come along with a better explanation, but generally I've seen that camel radioulnas are much slimmer than those of bison, and the fusion area between the radius and ulna is completely closed - in bison, there are little gaps in between where the bones are fused, so that you can still make out where one bone ends and another begins. Sometimes you can see all the way through these tiny gaps, sometimes you can't. 

Thanks! Great info. I’ve seen pics of these gaps on bison but wondered if they were of juveniles that hadn’t completely fused yet. Are camel radioulnae unfused as juveniles? When I look at pics on line I see no seam or any evidence that the radius and ulna were ever two distinct bones.

[Uncle Siphuncle]

For reference, the adult Camelops radioulnas I’ve found are 22-23 inches long with a distinct D shaped cross section of the diaphysis.  Very gracile looking compared to stocky Bison radioulnas, which might reach around 18” +/- (from memory).  As mentioned above, the less complete fusing of the Bison ulna leads to it often being detached by the time we encounter it.  It seems that every time I bump into a full length camelid radioulna, the ulna is still attached, and this includes all the way back to Miocene (Alticamelus?).

[Lorne Ledger]

Since you have the fossil in hand, see how it compares to this image

That is from Mammalian Osteology by Miles Gilbert, everyone should have a copy of that book

[LabRatKing]

25 minutes ago, Lorne Ledger said:

Since you have the fossil in hand, see how it compares to this image

That is from Mammalian Osteology by Miles Gilbert, everyone should have a copy of that book

Just the guide I have been searching for...ordered!

[ClearLake]

28 minutes ago, Lorne Ledger said:

That is from Mammalian Osteology by Miles Gilbert, everyone should have a copy of that book

I will also vouch for the usefulness of this book, it is very helpful.  There is also a companion to it, Avian Osteology, also by B. Miles Gilbert.

[jpc]

me too.... even though I rarely deal with Pleistocene stuff, this book is great for learning what a femur looks like comparted to a humerus, and also for IDing modern bones and teeth.  

He did one for bird bones as well.  

[garyc]

2 hours ago, Lorne Ledger said:

Since you have the fossil in hand, see how it compares to this image

That is from Mammalian Osteology by Miles Gilbert, everyone should have a copy of that book

Thanks @Lorne Ledger. Mine is completely fused. I’m leaning toward camel