JonathanH
But taxonomy while having a function in biology, is from a pragmatic standpoint just a human invention to catagorize things we see a relationship in. If you travelled back in time five thousand years and showed somebody a french bulldog, do you really think they would make the connection that this thing is in fact of the same "kind" (whatever that means) as the vicious pack hunters that they were gradually bred from? Or would they think that this snorting, short, stocky, boxy shaped animal is just another wierd creature that they've never seen before? There is no such thing as "kind", there is no "dog gene" that makes a dog a dog, and not some other animal that is part of a different "kind". We mistake taxanomy which is simply catagorizing things that are similar (and today they are catagorized by evolutionary and genetic lineages, and not simple morphological similarity as ancient people would've done), as concrete lines seperating one thing from another. They are not. Life is just blending shades of grey.
I think you nailed it (even though we have probably reached different conclusions), but isn't that a two edged sword? Using bones/fossils alone to solve this problem (or answer the question) leaves way to much room for speculation and controversy.
Of course the answer to that is obvious to those that took any courses in biology or genetics. There isn't one. A species diverges (or rather a speciation event occurs) not because some essential part of their gene changes, but because a large enough portion of their genes have changed that they can't succesffully produce offspring anymore, and due to sexual selection, they probably wouldn't try to anyway.
Oh... really? Well... if that's the real definition of species, why are we even looking at bones and fossils at all?
Using dogs for example, look at the huge variety in one single species, compared to the few in the photos above (which is supposed to represent two). I wish I had a picture of all the different breeds side by side, yet they are all one species.
TD
BTW Good topic.