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<<Cladistic trees do not give direct ancestor-descendent relationships on the large scale, they can only give more vague relations because human scientists were not living back 600 million years ago to witness the birth of animals; the only way we can be scientific is by not explicitly positing ancestor-descendent relationships, and letting the trees speak for themselves.>>

<I hope you will clarify this a bit. Cladistic definitions are stated in terms of ancestor/descendants. I think you mean that one known animal is not necessarily ancestral to another known animal, but I want to be sure.>

You're right, I AM saying that you cannot, ever, tell with certainty that _Archaeopteryx_ is the direct ancestor of all later birds, including living ones. We weren't back 145 mya and later to see what happened to _Archaeopteryx_ and its (possible) descendents. Cladistic definitions are based on common ancestors but these are never explicitly given since we can never, ever tell what it might have been.

<<By not including birds within dinosaurs we are going back to the days of typology where birds were seperate from everything else on the planet (as were dinosaurs).>>

<Isn't a choice made about what group gets a separate name? You could presumably have only one group allowed for all animals and plants, but people have chosen to identify some sets of animals and plants separately. The source of the connection in these groups is evolutionary and rules for naming are established, but is there anything necessarily anti-evolutionary about calling birds a separate group?>

I don't quite understand what you're saying. Typology is a way of thinking where the major groups of animals, plants, fungi, whatever, are set. Philosophically, it goes back to essentialism: you have the metaphysical 'ideal', for example a cup, and somewhere this 'perfect', immutable 'ideal' cup is the design (or type) for every cup. This is explicitly Platonic in thought. Typology is the biological equivalent of essentialism: there is a basic blueprint, template, or type for every bird, for example, and every bird is built from this template but the template cannot come from something else, a reptile template, or turn into something else. Typology does not allow for much evolution.

Matt Troutman
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