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

RE: Brochu's avian article in latest JVP

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Betty Cunningham
> Hoever the article >seems< to
> be addressing Feduccia and Martin's claims to a crocodylian origin for
> Aves, and yet none of the phylogenies discussed were that of Mssrs
> Feduccia and Martin.
> I know there's a great deal of cladistics I don't understand but this
> seemed rather odd to me.  Is it that Feduccia and Martin have not
> suggested a phylogeny, so that it can't be discussed?

And the survey says...
The number one answer!

The anti-dinosaurian origin of birds crowd is just that: against the
dinosaurian origin of birds.  They aren't pro-something else in particular,
just anti-dinosaurian origin of birds.

They have not offered one or more specific alternative phylogenetic
hypotheses.  They imply that _Longisquama_, or _Megalancosaurus_, or
sphenosuchians, or _Lagosuchus_, or _Euparkeria_, or so on might have
something to do with bird origins, but not more than that.  They don't (or
very rarely) come out and say, for example, that birds are more closely
related to _Megalancosaurus_ than to dinosaurs, but rather say that the
"strikingly bird-like" _Megalancosaurus_ may give us important insight into
the origin of birds and bird flight.  Yeah, it might give us insight.  So
might sifakas.  So might chameleons.  So might fruit flies.  (Okay, maybe
not MUCH...).  However, that is different from the question the rest of some
of us are trying to answer: namely, where do birds fit among the archosaurs
on the Tree of Life.

There's nothing wrong with proposing a phylogeny that is later found to be
less well-supported when additional data comes along; I've done it myself.
I just which that Drs. Feduccia, Martin, and company would give one or more
(more is fine, I have no problem with more) specific phylogenetic hypotheses
so that we can compare these alternatives.  That was what Brochu was trying
to do in his paper: fit the pseudo-phylogenetic statements into a
phylogenetic framework.

Martin has come close: he's offered, for example, his cladogram in DinoFest.
However, that was actually addressing the position of _Mononykus_, not
birds: birds wind up outside the outgroup (!!) in that study.  He has also
said (at the 1999 SICB conference) that he suspects birds arose from taxa so
primitive that we might not even call them archosaurs (using the Romerian
version of the term, by interpretation: I take this to mean taxa currently
considered basal archosauriforms or archosauromorphs).

Hope this helps

                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): 301-314-7843