On 26/08/2013 03:49 PM, Warp wrote:
> For example, all terrestrial tetrapods (which includes us) have the
> same basic limb bone structure: One bone (upper arm) ->  two bones (lower
> arm) ->  a bunch of small bones (wrist) ->  a group of long thin bones
> (palm/fingers).

In a way, that's pretty amazing. But in a way, it would be far more 
amazing if all these animals did *not* have the same bone structure - 
that would imply a sudden change in skeletal design, which is quite 
unlikely.

> (In some animals the limb's end may have changed so that eg. a toe has
> grown into a hoof, but the basic structure is still discernible.)

Take a dog, for example. The part of a dog's leg that *looks* like an 
elbow is actually homologous to the human wrist joint. The *actual* 
elbow is hidden inside the dog's body where you can't see it. And the 
thing that looks like an angle is actually our finger joint. It's whacky 
stuff...

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