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Re: Rconstructing DNA (was Re: Dino-fuzz found in amber?)
What you can do with *paleontology*? You never will find courtship
behaviours, colours of the most (oh wait!)...
The methodology is sound enough to molecular biologists use this
techniques and reconstitute ancestral sequences.
First, are you sure you haven't misunderstood the technique? Are you
sure it doesn't involve phylogenetic bracketing right from the start, so
that you need a bird _and_ a crocodile -- or, rather, the ancestral
neornithean and the ancestral (crown-)crocodylian sequence -- _before_
you start comparing the *Tyrannosaurus* aa sequence to anything?
Because that way, you would _inter_polate. What you did was to
Second, it has happened before that molecular biologists used unsound
techniques. The literature on molecular dating is full of papers that
use completely erroneous calibration points (and too few of them), and
even fuller of papers that use all calibration points as maximum ages
and thus arrive at much too old dates.
The rationale is basically the same as the morphological
phylogenies. We can infer that the most recent common ancestor of
protostomes and deuterostomes had bilateral simmetry. There are many
characteristics that are inferred for the Urbilateria.
Even for Cenancestor or LUCA.
Absolutely not. All conclusions about them are drawn from
_inter_polation: you compare descendants and draw conclusions about
their common ancestor. You do not go beyond that.