Re: Class AVES expanded (preliminary classification)

["Mickey_Mortimer11" <Mickey_Mortimer11@email.msn.com>]

Ken Kinman wrote-

>       I have thought about this long and hard for well over a year, and
have
> come to the conclusion that Class AVES should be expanded to include
> maniraptors which possess so many bird characteristics that they should be
> called birds.  It will be an apomorphy-based taxon that is approximately
> equivalent to the cladistic stem-based "Maniraptora".

Sigh.  But why not include ornithomimosaurs too?  After all, they lack only
a few synapomorphies that maniraptorans have.  And tyrannosauroids are so
close to maniraptoriformes, that they've been placed inside the clade by
various authors (Sereno 1999, Holtz 1994, etc.).  Might as well include them
too.  Then we have the other basal coelurosaurs...  You get the picture.
Aves is already happily defined as Archaeopteryx + Neornithes (finally
dispelling the Gauthier-esque use of Avialae for this clade), we don't need
any changes now.
I need not expound on the whole "Class" thing, nor the problems of
apomorphy-based taxa.

>       The fact that Archaeopteryx was so long considered the first bird
was
> just an accident of history, but new fossils (from China in particular)
now
> almost cry out for a paradigm shift that is reflected in our nomenclature,
> both formal and informal.

Yeah, but what ya' gonna do?  Have to start Aves somewhere, might as well be
there.  We're only going to find more taxa between Archaeopteryx and
Microraptor and Rahonavis on one side, and Yandangornis and Sapeornis on the
other.

>      This expanded Aves will now include (but not be defined by) forms
that:
> (1) possess vaned feathers; (2) possess eggs with ornithoid
microstructure;
> (3) possess lateral shoulder joints; (4) enlargement of sterna; and
various
> other bird characteristics.

The first character seems to be between Coelurosauria and Maniraptora.  The
second is not true of segnosaurs.  The third is absent in Sinornithoides,
probably some segnosaurs and oviraptorosaurs, alvarezsaurids, Achillobator,
etc..  Troodontids, segnosaurs, Protarchaeopteryx, Caudipteryx, Mononykus
and other maniraptorans have unossified or non-enlarged sterna (I haven't
quantified, but Baryonyx seems to have comparable sized sterna for
instance).  Hence the problem of apomorphy-based taxa.

> 3  Plesion Alvarezsaurus
> B  Mononykiformes
>         1  Patagonykidae
>         2  Parvicursoridae
>         3  Mononykidae

Why the reluctance to place Alvarezsaurus next to Patagonykus and
mononykines?  Where else could it go?

> But a crown-group Aves has already been proposed and noone uses it.  And
this
> modestly expanded Aves does not equal Maniraptora (which is stem-based),
and
> the latter name isn't particularly appropriate for the whole group anyway
> (since most birds don't go around "manuraptoring" their food).

That's because we already call it "Neornithes".  Making the well-established
Maniraptora a virtual junior synonym of Aves isn't useful.  It's not like
Aves is appropriate for all maniraptorans either, who would call
Therizinosaurus or Achillobator a bird?  Besides, you don't rename a clade
because the previous nme is inappropriate.  It's not good nomenclature, just
leave the few agreed upon parts of our trees alone.

George Olshevsky wrote-

> I think we should restrict the name Aves (from Latin for birds) to the
> smallest node-based clade that includes all extant birds (this is its
> original and traditional usage), and create a name Ornithes (from Greek
for
> birds) for the largest stem-based clade that includes Aves. Ornithes would
> then include all the dinosaurs and dino-birds, as well as any other
> archosaurs more closely related to extant birds than to extant
crocodylians.

Isn't the largest stem-based avian clade already named Ornithosuchia?

David Marjanovic wrote-

> Big semilunate carpal: apparently a synapomorphy of *Ornitholestes*, birds
> and everything in between (whatever that is). Is that an idea?

No carpus known for Ornitholestes.  Coelurus, Scipionyx, Nqwebasaurus and
tyrannosaurids have similar non-enlarged semilunates.  Also similar to
Allosaurus and Acrocanthosaurus I think.  True semilunates evolved in
enigmosaurs + paravians.

> Parvicursorinae was named as a subfamily (of Alvarezsauridae) that
includes
> *Parvicursor* and *Mononykus*. Mononykinae was (later) named as a clade
that
> includes the most recent common ancestor of *P.*, *M.* and *Shuvuuia* and
> all its descendants. Coding them as separate clades is IMHO impossible.

No, Parvicursorinae was NEVER published to my knowledge.  Karhu and Rautian
(1996) named Parvicursoridae and specifically excluded Mononykus from it,
although they viewed them as closely related.

> Plesia for *Yanornis*, *Yixianornis*, *Liaoningornis*... at the base.

Liaoningornis shows no evidence of being a euornithine, contra what is
"common knowledge".  Just read the paper.  Songlingornis, Yanornis and the
Archaeoraptor back end all are _very_ similar though....

Mickey Mortimer