[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Eumaniraptora stuff again......



> Date: Sun, 7 Sep 2003 11:18:50 -0700 (PDT)
> From: Steven Mahon <floridamahon@yahoo.com>
> 
> I've been reading previous posts about Eumaniraptoran
> phylogeny, & the whole "is *Archaeopteryx* a bird"
> thing. I've found some posts that say Dromaeosauridae
> is paraphyletic, & some dromies are closer to birds
> than others. Could someone sort this out for me?

No.

:-)

_No-one_ can sort you out definitively, because the phylogeny is up in
the air.  It's all just competing hypotheses.

Pretty much all you _can_ say with any certainty is that
_Archaeopteryx_ is a bird -- because it's one by definition.  The
standard definiton of Aves is {_Archaeopteryx_ + Neornithes}, that is,
the most recent common ancestor of _Archaeopteryx_ and common birds,
plus all its descendants.  So (asusming you use this definition -- not
everyone does), Archie is a bird; but what else is?  It depends on how
the phylogeny falls out.  For example, if it looks like this:

        +-- Carnosaurs
        +-- _Deinonychus_
        +-- _Archaeopteryx_
        +-- Modern birds

Then _Deinonychus_ is not a bird; but if it looks like this:

        +-- Carnosaurs
        +-- _Archaeopteryx_
        +-- _Deinonychus_
        +-- Modern birds

Then _Deinonychus_ _is_ a bird.

By the way, Dromaeosauridae can't be paraphyletic -- again by
definition -- since it's defined as the clade {Dromaeosaurus +
Velociraptor}.

Hope this helps.

 _/|_    _______________________________________________________________
/o ) \/  Mike Taylor  <mike@indexdata.com>  http://www.miketaylor.org.uk
)_v__/\  "Purer than the sky behind the rain ...  Love had lit a fire,
         we were the flame" -- Amy Grant, "1974"

--
Listen to my wife's new CD of kids' music, _Child's Play_, at
        http://www.pipedreaming.org.uk/childsplay/