On 11-4-2010 22:36, Warp wrote:
> On 04/11/2010 11:29 PM, Warp wrote:
>>   This doesn't mean that birds did not evolve from theropods. It means
>> that birds are not dinosaurs because they do not belong even to the same
>> taxonomic class (aves vs. reptiles).
> 
>   Let me put that in another way. If birds were dinosaurs, then you
> should be able to say:
> 
>   "Birds are dinosaurs, and dinosaurs are reptiles, hence birds are
> reptiles."

See christian for a part of the answer. Though I disagree with him 
agreeing with this logical fallacy. The correct version is

"Birds are dinosaurs, and dinosaurs (except birds) are reptiles, hence 
(sorry no hence)."

>   If birds were - indeed - dinosaurs, that *would* make them reptiles
> because dinosaurs are classified as reptiles. However, birds are *not*
> classified as reptiles. Hence birds are *not* dinosaurs.

A good example why paraphyletic groups are not a good idea. It leads to 
logical inconsistencies like this.

>   Just because birds *evolved* from dinosaurs doesn't change that.

No, but changing definitions of what a dinosaur is might. Actually, I 
think the debate will go on for some time because the classification of 
birds as something special is too logical for many people and the images 
of dinosaurs with scaly hides are too widespread. Probably there will be 
(and probably there already are) two 'definitions' of dinosaur. One 
paraphyletic version in common use that won't include the birds and a 
taxonomical that does, with the taxonomical slowly becoming more common 
when also the children books incorporate it.

Twenty years ago you would have been correct, today a case could be made 
for both opinions (though I think mine has the much stronger case). 
Whether in another 20 years many people will still defend birds as being 
a distinct class next to the reptiles and mammals I would doubt. Frankly 
I think that by then even you have changed your opinion.

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