Re: Digit Loss

[Raymond Ancog <rayancog@pacific.net.ph>]

Daniel Bensen wrote:

>     We see numerous examples of digit-loss in tetrapod evolution, but no 
> digit creation.  The closest instance I can think of to digit creation 
> (except for aberrant things like two pinkies---which don't seem to 
> propagate through breeding(has anyone looked into that?)) is the panda's 
> thumb, actually an altered set of wrist bones, that went through all 
> sorts of intermediate mutations before arrive at its present, functional 
> state.  Any seeming tendency for digit-reduction is due to the fact that 
> more-toes mutations are much harder to achieve than less-toes mutations, 
> and so the less-toes mutations tend to build up over time.

What about the hyperphalangy in ichthyosaurs? And isn't the pteroid bone in 
pterosaurs analogous to the panda thumb, also an altered (meta)carpal?


Raymond Thaddeus C. Ancog
Mines and Geosciences Bureau
Philippines