Grant,
I sorted through all the unpolished sets they had and chose the thickest set that had no evidence of porosity on the inside, which was the flat side of each piece. Based on the radius of the porosity showing on some of the pieces, I can only assume these were tibias, but I have no way of knowing for sure, and I'm sure that the folks at TKS don't know.
I asked the store manager if they received the pieces as bulk (because they do shape a number of handles from bulk pieces of various materials), or if they received them already shaped. He told me that they got them already shaped. So this tells me that we're talking about a bone diameter that is probably in the neighborhood of 2" to 2.5"(including the porosity evidence I mentioned above). Not being conversant on camel physiology, this is why I'm assuming they are from the tibias, but I wouldn't be willing to bet on it
Unless I were butchering the animal or knew somebody who was, I suspect it would be difficult to insist on metacarpals or metatarsals as a preferred bone material. Good to know your preferences, though

Next time (if ever) I have that opportunity, I'll make my preferences known. Just curious, can you get an 88mm long nut out of a moose metacarpal/tarsal?
Best,
Michael
Michael McBroom38878.4016666667