Dead somethings or other answers (?)

31 07 2013

Thankfully, we caught Wouter, the bone expert, right before he took off for vacation. Also, I highly recommend visiting Wouter’s website, especially if you wish to take a bird skull quiz that will demoralize yet enthrall you. I scored a 928 out of 1200, which I deem respectable since I don’t know anything about these European jobbies like “hawfinches” and “bullfinches.” You will be pleased to know, Seanetters, that I knew the Gannet right away.

In any case, to remind you about the current quiz, here are the bones in question:

All the bones arrayed. (photo: E. Boucher)

All the bones arrayed. (photo: E. Boucher)

Wouter wrote:

“Indeed these bones are not from one animal. From left to right:
broken ulna bone (lower arm) of a bird, 2 x humerus (upper arm) of a bird, an a vertebra of which I cannot say much, 2 x radius bone (lower arm) of a mammal, and a tibia bone (lower leg) of a bird.
Maybe I can make a guess of what bird(s) are involved later, but I’ll leave for a 2 week holiday next Monday as well.”

I am not generally so good at this as Wouter, but I did pick out the bird humeri and knew that the two bones with the c-shaped groove at the top were mammalian. But there, I do differ from Wouter. Those bones with the c-shapes look very like mammalian ulnas (ulnae?) to me. The ulna and radius are the bones of the forearm, and they meet the humerus (upper arm bone) at the elbow. In mammals, the ulna has a deep, half moon shaped groove to accommodate the trochlea of the humerus. The ulna can thus slide over the humerus as the elbow is bent and straightened.

The ulna (bottom bone) cups the trochlea of the humerus (bone running vertically up the image)

The ulna (bottom bone) cups the trochlea of the humerus (bone running vertically). The radius, in back, has a flat head.

Dog elbow. Note how squared off the top of the ulna (the olecranon process) is.

Dog elbow. Note how squared off the top of the ulna (the olecranon process) is.

By contrast, the radius, which sits right next to the ulna, has basically a flat top that wedges up next to the humerus.The thing about these bones that I think are ulnae is that they lack the prominent olecranon process at the top with which I am familiar from my vet school anatomy days. Dog ulnae have a big, squarish olecranon jutting up above the c-shaped groove. Not all mammals have that feature; cats, for instance, have a more sloping olecranon. Weasels, and raccoons, kind of in the middle. In short, I do not know whose ulnae these might be, but I do feel confident that they are ulnae, and mammalian. Then again, I did only get a 928 on the skull quiz.

All this talk about mammal bones has made me, if not nostalgic for, then at least susceptible to the memory of my first year of vet school, when each student was loaned a bone box–a disarticulated dog skeleton in a tackle box. (They were plastic model bones, much to my great disappointment). I would study at home with my bone box and my pet birds out and about on the table. If you ever wondered about the relative supremacy of birds versus mammals, I need say nothing beyond what this picture can tell you.

Birds in the bone box.

Birds in the bone box.

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One response

5 08 2013
Wouter van Gestel

You are right, I mixed up the names of ulna and radius, thank you for correcting it. I’ll see whether I can say anything more on the bird bones later this week.

Wouter

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