Friday, August 29, 2008

Pterosaur Digits

Folks, a fella named Jim Cunningham email me today, suggesting that pterosaurs lost their thumb (rather than their pinkies), and that the wing finger is actually Digit V. This seems false. From what I've read and have been told, pterosaurs lost their fifth finger, and that they retained fingers II-IV. But after telling Jim this, he responded thusly:

"Pterosaurs have no thumb. It was the one that was lost. The digits are I, II, III, & IV with IV being the pinky finger which is also the wingfinger. If you'd rather not believe me, you might ask Chris Bennett, Kevin Padian, Wann Langston Jr., Peter Wellnhofer, John Conway, Mike Habib, Dave Unwin, or Greg Paul. Conway will be off on his honeymoon this coming week, so he probably won't respond immediately. All the best."

Those are some big names. Have I been wrong all these years?


Sciroccopteryx said...

Ah... digit I IS the thumb. At least... that's what I've always seen in every anatomical reference I've looked at- digits are numbered medial-lateral.

Granted, I haven't seen half the anatomical stuff I'd like to, but I've never seen them numbered lateral-medial.

Christopher said...

Yes, digit I is th thumb. The pinky is digit V.

This is the first I've heard of the wing finger being digit V. Well actually its not, there was a hypothesis regarding the pteroid actually being digit I and thus shifting all the digit homologies down one, but it is the first time Ive heard this particular incarnation and it given such strong support. And Im a little surprised its here that I learned of it and not the DML or an abstract or hinted at in a published source somewhere. I know Bennett does have a paper in press regarding the forelimb but as far as I know its in regards to the homologies of the various muscles that control the deployment of the wing.

If this isnt some miss understanding, you havent been wrong. This is new and the wing finger has always until now, and will remain so untill I see the reasoning behind it, been digit IV

Julia said...

There is a really detailed explanation here
I've posted about it a while ago on my blog but couldn't possible understand the entire explanantions