Re: Dromaeosauridae (was Troodontidae)

["Ken Kinman" <kinman@hotmail.com>]

Mickey,
    Well, there are so many different combinations and permutations of
genera that supposedly belong to Family Dromaeosauridae, it's hard to know
how much you would have to whittle it down to get a holophyletic group.
     Or perhaps it needs to be expanded to include Archaeopteryx, or a
combination of whittling and expansion.  Assuming Aves and Dromaeosaurs are
each others closest relatives (and even that is not a universally held
view), how to divide them so that they yield two sister groups is extremely
problematic.  Too tired to think about it tonight.
           Really got to get to bed,
                                Ken
*********************************************************
> From: "Mickey Mortimer" <Mickey_Mortimer11@msn.com>
> Reply-To: Mickey_Mortimer11@msn.com
> To: <dinosaur@usc.edu>
> Subject: Re: Troodontidae (misfits)
> Date: Sun, 8 Jul 2001 21:52:19 -0700
>
> Ken Kinman wrote-
>
> >       Just how secure is the holophyly of this Family Troodontidae?
> What
> > else could Sinornithoides be?
> >       And what about the unserrated teeth in Byronosaurus?  Could this
> > family be a wastebasket of two or more convergent clades of misfits?
> Are
> > they all really all that bird-like?  [Obviously I haven't given up the
> idea
> > that at least some of them might be bullatosaurian relatives of
> > ornithomimes].
>
> Very secure.  And I can't stress that enough.  It's like saying "how secure
> is the holophyly of the Tyrannosauridae?  What else could Gorgosaurus be?"
> Troodontids can be diagnosed by the following characters-
> - most distal posterior serration forming tip of tooth
> - enlarged elongate maxillary fenestra
> - dentary foramina inside lateral groove
> - calcaneum lost
> - tongue-like extension of articular surface on metatarsal III
> - metatarsal IV most robust in pes
> They also share the following, although some other taxa exhibit them too.
> Still, parsimony suggests it was convergence.
> - maxilla broadly contacts naris
> - nasals narrow caudally
> - numerous teeth
> - enlarged serrations
> - teeth with blood grooves
> - interdental plates absent
> - inflated parasphenoid
> - no basisphenoid recess
> - lateral depression in braincase
> - fibula reduced to splint
> - arctometatarsus
> The unserrated teeth of Byronosaurus are of no consequence.  It's actually
> a
> separate OTU in my analysis and always clades with other troodontids,
> despite the fact I don't have any of the non-homoplasic characters above
> included.  You're looking at the wrong taxa if you want to break something
> up.  Segnosaurs and troodontids are quite valid.  Try dromaeosaurids.
>
> Mickey Mortimer
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