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All the contributions on this are very interesting. I will follow up Phillip Bigelow’s comment that chickens are sometimes found with wing claws - I know a chicken slaughterer who should be able to give a rough estimate of the frequency. I knew he’d come in handy one day! The hoatzin is quite familiar of course, and I knew of others with some vestige such as the spur winged plover etc etc, (screamers again?! What is it with those things? Come to that, what and where are they? There’s a picture at http://www.wmnh.com/vbcsc5t.htm which unfortunately doesn’t answer more questions than it poses) but what I was trying to get at was a ball-park figure for spontaneous reappearance in individuals. My estimate now is that it’s pretty high. This poses the further question - why don’t flightless birds go the whole hog with the arms? John Bois reminds us that large flightless birds are arguably rather unsuccessful at competing with mammals, whereas their ancestors were relatively superior. If this is not down to changes in mammals, perhaps it is due to bird/dino differences: short tails, no teeth or no arms/hands. (Ornithomimids and tyrannosaurs had little problems with the last two categories though.) I suspect two barriers to re-evolving good hands: In flying forms, developing clawed hands and fingers would tend add weight and spoil the aerodynamic properties before they lent any other advantage. In Archaeopteryx the behaviour for benefitting from them had already evolved, as had any honing for minimising problems with flying ability. In flightless forms, the immediate tendency to minimise the wings would tend to prevent their becoming useful as hands. It would be possible I think but only artifically. Further investigations down that line should perhaps be left to a morals newsgroup (or perhaps not?!). I won’t comment more on it except to say that I predict a human/chimp hybrid will appear in the next century - and few people will avoid finding anything out about it in principle :-) If anyone has the reference to any phorusrhacid papers I for one would be interested. Thanks to Thom. Holtz and Chris Brochu for pointing out that some phorusrhacids were rather recent. I was being confused by a picture (I think by Greg Paul or uncle Bob) of a similar sort of bird holding a horse up in the air in its beak and waving it around - a very early horse of course! - and that WAS a very early tertiary bird. Try as I might I can’t find that picture now. (Sorry the unscientificness of my opening sentence frightened you Thom.! - I found holding your hands in front of your face and peeping through the cracks between the fingers quite useful for one or two mails in the "dinos above humans" thread!) Anyway - the interesting thing is just how recent was the last Ph? If their extinction really did coincide with the sabrecats’ and the mastodons’ then we might strongly suspect Mr Clovis. Their problem was us? (PS any Ph.s in the tar pits?) JJ |