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Re: "Feathery fossil shows birds aren't dinosaurs"
In a message dated 6/24/00 1:14:25 PM EST, firstname.lastname@example.org writes:
<< As far as the fossil record is concerned, BCF has no edge at all. >>
Sorry, you are dead wrong here. If birds >descended< from dinosaurs like
Deinonychus, Velociraptor, and so on, then we should be finding such
dinosaurs in the Jurassic >before< Archaeopteryx as well as after
Archaeopteryx. But we don't. They only occur >after< Archaeopteryx. All the
bigger theropods of the Jurassic are much more primitive theropods,
descendants of the much more primitive dinobirds of the Triassic and early
Jurassic. BCF predicts you'll find only dinobirds in the Jurassic and
earlier, not dromaeosaurids, because dromaeosaurids descended from slightly
pre-archeopterygid dinobirds. This is what the fossil record shows so far.
Some people have found a few little teeth and such from the Jurassic that
they identify as dromaeosaurid, but these are almost certainly dinobird
teeth--which were retained by their dromaeosaurid descendants.
The big problem is that dinobirds were small animals not easily recovered as
fossils, whereas their larger descendants made for large fossils. This
collection bias has strongly skewed the understanding of how theropods and
birds are related, as your post demonstrates.