On 27-8-2013 23:09, Patrick Elliott wrote:
> On 8/27/2013 10:20 AM, Orchid Win7 v1 wrote:
>> I was thinking more like if there was one member of the frog family
>> which has five legs instead of the usual four, or something. THAT would
>> be weird...
> Yeah, well.. That isn't likely to happen, six maybe, since you have the
> whole bi-lateral symmetry thing going on, but then, you would find that,
> much like "missing" ones, the extras are either a) caused by
> environmental toxins (common issue with frogs in fact), or b) a copying
> on the genes needed to produce the limbs. Whether or not, without other
> regulatory changes, you can get "functional" ones is another matter.

During evolution, Nature does it the other way round. During the 
Devonian when lobe-finned bony fishes appeared and evolved into 
amphibians, Nature experimented with different possibilities. There were 
animals with 7 or more numbers of digits on their legs. Eventually, only 
the animals with 5 digits made it. All the others became extinct.

Search for Acanthostega, Ventastega and Tiktaalik.

Thomas

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