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Re: Doesn't George have a point?



On Thu, 29 Jun 2000, Larry Dunn wrote:

> Not that I believe that dinosaurs evolved from birds
> per se (“A planet where apes evolved from men?!?!?”),
> but doesn’t George have a point when he says that the
> lack of a suitable known dinosaur ancestor of birds in
> the appropriate time period raises some really serious
> doubts as to the dinosaur ancestry of dinosaurs?  

This has recently been discussed _ad nauseam_ in <sci.bio.paleontology>.
There actually are non-avian maniraptoriform fossils from the Late
Jurassic. They are fairly fragmentary, but even if there weren't any,
absence of evidence is not evidence of absence, *especially* in the fossil
record. Several maniraptoriform lineages have gaps of over 20 million
years during the Cretaceous, from basal EK members to advanced late LK
members.

Consider also that when non-avian Maniraptoriformes first do appear
unambiguously, in the Early Cretaceous, they have already diversified.
Thus, they must have had some ancestor in the Jurassic.

As I understand it, George's model doesn't differ much in its phylogeny
from the mainstream. The main difference is in what the animals along the
lineage from the first theropod to the first avian looked and acted like.

____________________________________________________________________________
T. Michael Keesey <tmk@dinosauricon.com> | AIM <Ric Blayze> | ICQ <77314901>
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