There are plenty of myths out there in science – things that persist in the public imagination long after science has moved past or shown them to be inaccurate. As such, researchers tend to be a bit careful about taking things for granted that they think they know when the source might not be entirely accurate. Even so, we are only human and it is natural that everyone has a couple of false-facts in their repertoire that require someone come along and pop every so often. This is one of my favourites that has actually come up in discussion with colleagues more than one to their incredulity. The aye-aye, does not have a long 3rd digit in the hand.
Ok, so all the fingers of the aye-aye are very long, but while most people (who know a bit about aye-ayes) seem to know that the 3rd finger is the specialised thin finger used to extract grubs from trees and the flesh from coconuts, many think it is the longest in the hand, putting it at odds with other primates. Not so. This idea is surprisingly persistent and I’ve had to furnish photographic proof to more than one colleague about this.
Happily, I was able to get a nice photo of an aye-aye skeleton here in Dublin. They could be better and the hand is mounted gripping a branch, but hopefully it is clear the third finger is quite simply not longer than the fourth. Simple proof of a very simple point. Still, it hopefully serves as a bit of a warning to others not to take ‘common knowledge’ for granted.
Dave Hone's Archosaur Musings 
Never knew that. Neat!
Never knew that 3 was shorter than 4, or did you actively think that 3 was the longest? That’s not an accusation, I’m genuinely intrigued to see how widespread this might be given that for me it has come up a few times.
I must confess that I also thought that the third finger was the longest finger, probably fueled by the fact that my own third finger definitely looks to me to be the longest on my hand!
Well it is longer in many things, but the tetrapod default is a long 4.
Didn’t know that, either. Too much dinosaurs for me.
I cover this a bit in the essay on the pterosaur hand and why the long finger is the 4th one.
I just corrected Wikipedia on this changing “long” and “elongated” to narrow/thin.
The image doesn’t show – my browser displays a red cross.
Try clicking on it. It is there, so i assume it’s a problem your end since I can see it and obviously others can too. I’ll try and shrink it a bit which might help.