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?