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Re: Sinosauropteryx filament melanosomes challenged

On Tue, Dec 7, 2010 at 3:14 PM, Matthew Martyniuk <martyniuk@gmail.com> wrote:
> On Wed, Dec 8, 2010 at 3:37 AM, Â<vultur-10@neo.tamu.edu> wrote:
>> Since there's no clade "turtles + snakes + lizards + crocodiles + tuataras" 
>> (all the scaly, egg-laying cold-blooded animals) to the exclusion of birds, 
>> which is what 'reptile' has meant for at least a couple centuries, using 
>> Reptilia as a clade *at all* just seems designed to confuse.
> Just to play devil's advocate, why is this true of Reptilia but not
> Dinosauria? "Dinosaur" had meant saurischians and ornithischians (plus
> various non-dinosaurian ornithodirans and crurotarsans) to the
> exclusion of birds for over a century before it was re-defined to
> include birds in the '80s. What's the cutoff time for declaring that a
> name is salvageable due to tradition? Why is "birds are dinosaurs" ok
> but "birds are reptiles" is not? (Or "birds are fish", for that
> matter?)

This is a good question.

I think the biggest issue here is alternative names. Many paraphyletic
groups already have names for their corresponding clades, so it
doesn't make sense to convert the name of the paraphyletic group.
"Pisces" has Vertebrata and "Reptilia" has Amniota or Sauropsida
(depending on usage). "Dinosauria", on the other hand, has no
alternative. (Unless there's some obscure term buried in the
historical literature that I've overlooked.)

T. Michael Keesey
Technical Consultant and Developer, Flex Specialist
Glendale, California