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Re: Re-emergence of lost features.
At 06:59 PM 13/03/1998 -0000, John Jackson wrote:
" . . .the phorusrhacoids (a group of extinct, flightless, predatory birds) re-evolved large, clawed hands with mobile fingers. They doubtless used these hands in subduing their mammalian prey and evolved their hands from typical avian wings. Phorusrhacoids also developed large, recurved claws on their second toes . . ."One may wonder whether the genetic information to redisplay an old feature can still be there after tens of millions of years
As I understand it the phorusracid "clawed hand" was not the redisplay of an old feature but the rejigging of the bird wing so that the hand, instead of folding back at the carpal joint, projected forward forming grasping claws modified from the fused fingers - in other words, they evolved a new structural arrangement unique to that group that functioned in, presumably, a similar fashion to the maniraptorian hand. If this is so (and I have not seen the original papers) then we cannot assume that the "reawakening" of earlier genetic information was involved.
Ronald I. Orenstein Phone: (905) 820-7886
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