Re: birds and avians again

["João S. Lopes Filho" <jodan99@uol.com.br>]

This is a endless discussion.
We have:
1) the vernacular definition of Aves
2) the Linnean definition of Aves = feathered, winged, cold-blooded
oviparous vertebrates
3) the cladistic-genetic definition of Aves

1 and 2 are virtually the same, unless we consider bats as birds in some
languages and cultures.
3 is almost impossible to define.

----- Original Message -----
From: Jaime A. Headden <qilongia@yahoo.com>
To: <dinosaur@usc.edu>
Cc: <Dinogeorge@aol.com>
Sent: Friday, August 31, 2001 6:57 PM
Subject: Re: birds and avians again


> Mike Keesey (tmk@dinosauricon.com) wrote:
>
> <<"Bird" is a vernacular English term and hence its usage is dictated by
the  English-speaking
> public at large. I think it's pretty clear that most types of dinosaur do
not fall under the
> common usage of "bird".>>
>
> George Olshevsky (Dinogeorge@aol.com) wrote:
>
> <This is merely a historical accident that I think should be rectified. We
now know that dinosaurs
> are more closely related to modern birds than they are to any other group
of living animals. So it
> makes a lot of sense to expand the definition of "bird" to include
dinosaurs and any other
> archosaurs that fall into the stem-group "birds" that I described. As far
as formal naming of
> these groups goes, one could stick with a node-based Aves (Latin root
"birds") for the clade
> including and descended from the last common ancestor of Archaeopteryx and
modern birds, a la
> Linnaeus, and then name the more inclusive stem-group birds Ornithes
(Greek root "birds"). (But I
> don't like pinning a major group like Aves to a single genus such as
Archaeopteryx: if we find a
> slightly pre-archaeopterygid fossil flying bird, why arbitrarily exclude
it from Aves?) The other
> extant archosaur crown group would retain the familiar node-based name
Crocodylia, and the more
> inclusive stem-group crocodiles (all archosaurs more closely related to
Crocodylia than to
> Ornithes) would become Suchia.>
>
>   I hate to be a rainy day in Seattle, but I would like to know what you
think others would take
> to calling placodonts "turtles" or "chelonians", especially Gaffney and
those whose primary worl
> is with turtles. Gaffney, as you may know, is a phylogenetic operator in a
cladistic scheme, as
> are most AMNH workers. Gaffney is also the leading authority on fossil
turtles.
>
>   Such redefinitions are unneccesary, in my view, as they only tend to
confused the association of
> terminology and clades, and would seriously screw with history. And
aesthetics. The term bird does
> not in any way encompass titanosaurs in it's historic, aesthetic, visial,
or mental paradigm, for
> anyone, I think, except George at this point. I would like to know a
concensus of the listmembers
> on what they think a "crocodile" or member of Crocodylia is compsed of,
but we have done "bird" to
> death, and most everyone on this list anyway, appears to be in agreement
with the historic method.
> I am curious if this is the public that must be informed, those who work
on the animals
> themselves. In any way, shape or form, the term bird does not bring to
mind a titanosaur,
> quadrupedal and armorod, unfeathered, a long tail, no pygostyle, a
propubic hip arrangement, no
> beak, no folding wrist, a humeus that could not elevate, no reversed
hallux, certainly not a
> similar palatal arrangement, etc.... These do not incorporate anyone's
view of the term "bird" or
> the idea of Aves. By similar token, it is uneccessary to name a clade
Ornithes unless one wishes
> to define it to include dinosaurs and birds in the aconventional model,
where they are kept as
> separate "classes" of some sort.
>
>   Please note, I am not in any way a conformist, but I cannot see the
logic in this revisionary
> system that attempts to apply a strict vernacular idea to fossils, based
on extant relationships.
>
> Archosauria: *Crocodilus* + *Corvus* [Neornithes, but we should use a a
specific genus, and the
>       crow is more familiar to the world than just a sparrow is, so is
emminently more viable in
>       my mind.]
> Aves: *Archaeopteryx* + *Corvus*
>
>   I beleive both Chelonia and Crocodylia use fossil specifiers/anchors,
but I cannot recall them
> off the top of my head. Tetrapoda as well. Amniota is a stem excluding
lissamphibians, and
> Synapsida is a stem from Sauropsida, or conventionally, Reptilia. Reptilia
is a crown group clade
> comprising Chelonia, Lepidosauria [incl. snakes and mosasaurs],
Crocodylia, and Dinosauria [incl.
> birds]. That these groups are already viable and the vernacular applies to
them easily, it would
> seem that the only reason they should not be used is the basis of fossils.
However, the fossils
> themselves are well-founbed and studied, and do not shift substantially.
Reptilia will always
> include Chelonia, regardless of which diapsid group it is closest to, or
whether it is not at all.
> The crown group for birds can be Neornithes, and we can be satisfied.
>
>   Take the Encyclopaedia Brittanica, for instance: Vol. 2, [pg. 229-230]
"bird, warm-blooded
> vertebrate of the class Aves, unique in having feathers and forelimbs
modified into wings."
> *Archaeopteryx* is treated as the most primitive bird. You will find
similar definitions in more
> complicated texts, including the Encyclopedia of Dinosaurs, Dingus and
Rowe's Mistaken Extinction, etc..
>
> =====
> Jaime A. Headden
>
>   Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
>   Where the Wind Comes Sweeping Down the Pampas!!!!
>
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