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

Many things (was RE: Recoded Aves...; RE: Gauthier and de Queiroz's...)

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Mickey_Mortimer11
> David Marjanovic wrote-
> > Why Bagaraatan here?
> If Tom
> Holtz is reading this, perhaps he will tell us where it came out
> in his SVP
> analysis.

For what it is worth, it's bouncing around as the sister to (other)
tyrannosauroids, or a basal maniraptoran (outside the "enigmosaur"-paravian

> > It becomes then as easy as saying that ornithomime and tyrant
> > dinosaurs are sister groups because they have similar hindlimbs. Which
> > does not meet up with the recently presented evidence of the last two
> > years, though Holtz (2001) has supported somewhat Arctometatarsalia on
> > compeletly different grounds.
> Um, five of Holtz's (2000) seventeen tyrannosauroid + ornithomimosaur
> synapomorphies were hindlimb characters.  I wouldn't call that "completely
> different grounds".  Of course, his 2001 analysis excludes tyrannosauroids
> from Arctometatarsalia.

Just want to clear up that "Holtz (2001)" COULD refer to the Ostrom
Symposium (and thus 1999 work...) or my unpublished SVP presentation.  The
former found tyrannosaurIDs as arctometatarsalians; the latter found
tyrannosaurOIDs (based on additional taxa and additional data) as the sister
taxon to Maniraptoriformes.  (Incidentally, Sereno's 1999 matrix finds this
same position in trees only 1 step longer than the most parsimonious).

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Dinogeorge@aol.com
> In a message dated 2/12/02 3:33:08 PM Pacific Standard Time,
> TiJaWi@agron.iastate.edu writes:
> << Sounds like Pan-demonium. :-) >>
> In the long run, there will be six or seven names for every
> different clade.
> It's simply going nuts.

I have to agree with George on this one.  While I felt that the heart of
that paper was excellent (discussing the problems associated with the
questions "what is a bird" and "what is Aves"), I found the particular new
taxa and their definitions somewhat less helpful.

Incidentally, Avialae is about the only phylogenetically defined taxon that
has had ALL THREE types of definitions! (stem-based: Gauthier, 1986;
node-based: Wagner and Gauthier, 1999; and here apomorphy-based).

In particular, I voice the standard objects to apomorphy-based definitions
I've previously given.  For example, at what point is flight flight?  Does
wing assisted vertical running count?  Does short hops with wing assist
count?  If not, how far does the animal have to be carried by its wings in
order to be considered "flying".

(And all this is almost moot anyway, as it would be extremely difficult to
demonstrate flight for extinct animals.  Although we accept Archie as a
flyer, we don't know how good it was, nor can we test it.  (And picking up a
specimen from Solnhofen and tossing it doesn't count as a test, and will
likely get you arrested!).

Similarly, those taxa with integument apomorphy-based definitions might not
prove very useful, given that integument preserves only rarely.

As for Ji & Ji's paper: again, I wish that the authors had consulted more of
the literature on theropod taxonomy (for example, Padian et al. 1999 is not
listed in the bibliography).  Furthermore (and perhaps this is in part a
matter of translation), the authors confuse Ostrom's lack of evidence for
integument in Compsognathus for being evidence of absence for dinofuzz in
the latter: hence the name Aptilonia = A - ptilonia, featherless.

I will hold off comment on the Norell et al. paper, as it is due to undergo
a major update in a paper coming out... very, very soon (tick, tick, tick,
tick... ;-).

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796