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Re: Removing segnosaurs from ...



In a message dated 95-08-30 23:08:26 EDT, Thomas_R_HOLTZ@umail.umd.edu (th81)
writes:

>Reversals do occur sometimes in nature: there are apparent reversals in
>sacral numbers in the evolution of horses (granted, a simpler situation than
>the metatarsals.)
>

THOSE kinds of reversals I have no problem with. Indeed, such reversals
probably occurred more often than we guess, much to the consternation of
taxonomists(!). The kinds of reversals I have a very hard time accepting are
ones in which a substantial anatomical feature purportedly reappears after
vanishing entirely.

>And, as with any example of homoplasy, reversals can ONLY be identified
>posteriori after some form of phylogeny has been constructed.

Absolutely. Again, elementary stuff, but important to keep in mind.