Re: The Two Principal Dinosaur Clades Defined

[pharrinj@PLU.edu]

On Sun, 21 Jan 1996 Dinogeorge@aol.com wrote:

> In a message dated 96-01-20 03:22:57 EST, jpoling@infinet.com (Jeff Poling)
> writes:
> 
> >  So the problem we have here is one of semantics?  

It certainly seems like that to me.

> >The first dinosaurs
> >were small and arboreal that became large and cursorial in your theory,
> >rather than the mainstream theory of the first dinosaurs being large and
> >cursorial that evolved small and arboreal forms?
> 
> Right. But it's not _just_ semantics. BADD theory says dinosaurs evolved from
> bipedal cursorial non-dinosaurian archosaurs, and the forelimbs later turned
> into wings. BCF theory says dinosaurs evolved _as_ scansorial arboreal (or at
> least acronomic) archosaurs, some of whose descendants became cursorial
> bipeds while others remained acronomic and evolved into birds.

I don't know.  BADD seems like a straw man to me that no one believes 
literally.  Most authors I've read are pretty noncommittal about the 
structure and habits of hypothetical stem groups.


> >   If that is true, then BADD and BCF are not that far apart.  

Well, BADD and BCF are pretty far apart, but BCF and what most scientists 
actually believe aren't!

If I read you
> >correctly, the first dinosaurs weren't birds we would recognize today, they
> >were animals that people would recognize as dinosaurs (bipedal, erect
> >posture, S shaped neck, long tail, 2 - 3 fingered hand, three toed foot plus
> >hallux) if they saw them.  You're simply defining them as birds.
> 
> Definitely not a 2-3-fingered hand. The first dinosaurs had all five fingers
> and all five toes. 

I have to agree.  What you described is the first THEROPOD.  Just a 
technicality, though.

> >   I submit that may be a mistake.  The idea of "birds came first" doesn't
> >jive with me because I like the idea of birds descending from theropod
> >dinosaurs.  As far as I can tell, your BCF theory has birds evolving from
> >animals we would recognize as dinosaurs ... you've simply changed the names
> >to confuse the innocent.

Indeed.  I doubt that was the motive, but that's the upshot.