Re: Who says dromaeosaurs can't fly?

[John Conway <john_conway@mac.com>]

On Tuesday, September 17, 2002, at 01:12  AM, Brian Lauret wrote:

> I think we're getting a bit off subject by now.

What subject? :-)

> But I do want to give my view on the entire issue.
> I personally think the earliest evolution of birds may be unresolvable 
> by cladistic methods because I view the earliest bird (this is very 
> debatable of course,it's totally conjectural from my side) as the 
> earliest arboreal dinosaur with at the ability to fly.

Let's get this straight: cladistics is a method used to discover 
relationship, no more, no less. Cladistics can resolve phylogeny if 
given enough information; but it cannot provide us with answers about 
behaviour. If you define "birds" by a behaviour (flight) then 
cladistics can, in itself, provide no answers.

We should recognize that there is no group of organisms that are 
intrinsically "birds": we define what the word "bird" refers to. Your 
"earliest arboreal dinosaur with at the ability to fly" definition 
cannot be refuted, precisely because it is a definition, not a 
hypothesis. But many of us define the word "bird" differently, 
phylogenetically that is.

I, and many others, use "bird" and "Aves" as synonyms, if "Aves" is 
defined phylogenetically as _Archaeopteryx_ + _Vultur gryphus_. As this 
definition is based on phylogeny, and nothing else, cladistics will be 
able to clear up what is a bird, and what is not.

> At least that's how I view all of this....please comment me if you 
> think I've missed something or am wrong.

I think you may be missing the point that the argument is primarily 
about what to call "birds". Cladistics has nothing to say about the 
ability to fly. You definition of birds may need rethinking - many of 
us are not using it.


John Conway, Palaeoartist

"All art is quite useless." - Oscar Wilde

Systematic ramblings: http://homepage.mac.com/john_conway/
Palaeoart: http://homepage.mac.com/john_conway/_palaeoart.html