R: Class AVES expanded (preliminary classification)

["calzola" <calzola@iol.it>]

[The next "comments" may sound a bit naive, but here they are...]

I can't see the need for such an enlargment; the nodal points on cladograms
are just arbitrary points, chosen in light of some evidence at a given
hystorical moment. Having to move back the node only include other taxa -
not considered to be part of that group because of  different character
sets- because some (even a lot, which is the case here; i'm not questioning
this) characters match those of the taxa belonging to the to-be-enlarged
group is, IMHO, unmotivated.
I mean, it's kind of a baseless reasoning: Aves is diagnosed by some
characters;  maniraptorans show, among other characters, many avian ones ,
so we think it has some sense to enlarge the character set defining Aves
only to able to consider a cetain group as avian. And I think the latter is
the only reason for such a decision, because, at least to me, the fact that
some maniraptorans are the non-avian forms closest to the avian stock, is
just the more parsimonious descrpition of certain relationships and
_nothing_ more.
The presence of some characters in non-avian maniraptorans just ...reflects
the fact that these characters are not diagnostic of Aves but of a more
inclusive group(i.e.maniraptora, as George pointed out), nothing more;this
is just the best supported interpretation of this thing right now.
The obviously unreal gap between the basalmost avialian and  the more
"bird-like" non-avian theropods has just been filled by this newly
discovered  forms ,and I think it's completely unwise to think this couldn't
happen somewhere further back on the tree, just "before" ,say,maniraptora.
In the hypothetical(an much dreamt :-) situation in which all the forms that
once existed were known, it would be impossible to estabilish nodal points
on a tree without being asked << why "here" and not somewhere further down
or up?>>; naturally this will never happen and clades will always be
estabilished starting from groups of taxa recognized as sharing some
characters lacking in other forms, only because the latter are just too
"distant", and the closer ones are simply still in the ground or lost
forever.

FC
----- Original Message -----
From: Ken Kinman <kinman@hotmail.com>
To: <dinosaur@usc.edu>
Sent: Wednesday, January 23, 2002 9:21 PM
Subject: Class AVES expanded (preliminary classification)


> Dear All,
>       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".
>       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.
>      The precise synapomorphy (or group of synapomorphies) is not yet
> certain, but it will involve elements of the "folded" forelimb
(particularly
> in the wrist and manus).  I am certainly open to suggestions on which
would
> be the best and most precise synapomorphies for this new definition of
Class
> Aves.
>      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.
>      Furthermore, it will now contain those forms which display various
> degrees of pubic retroversion (including mesopuby).  Many of these forms
> have pelvic structures that are more bird-like, and they should probably
> never have been classified in Saurischia in the first place.  I believe
the
> time has come to expand Class Aves to include all these "birds".  I had
> already classified Order Mononykiformes in Class Aves in my 1994
> classification, so there are only two new Orders, namely Segnosauriformes
> and Caenagnathiformes (and these are obviously just Internet-type
manuscript
> names).
>      My preliminary classification is given below (Pl. is my abbreviation
> for Plesion):
> *****************************************
> CLASS AVEA (AVES)
>
> 1  Segnosauriformes
>         1  Pl. Beipiaosaurus
>         2  Alxasauridae
>         ?  Pl. Neimongosaurus
>         3  Therizinosauridae
> 2  Caenagnathiformes
>         1  Pl. Protarcheopteryx
>         ?  Avimimidae
>         2  Pl. Caudipteryx
>         3  Pl. Microvenator
>         4  Pl. Nomingia
>         5  Caenagnathidae
>         6  Oviraptoridae
> 3  Plesion Alvarezsaurus
> B  Mononykiformes
>         1  Patagonykidae
>         2  Parvicursoridae
>         3  Mononykidae
> 4  Plesion Troodontidae
> 5  Archaeopterygiformes
>         1  "utahraptorid" family
>         2  Pl. Pyroraptor
>         3  Pl. Bambiraptor
>         B  Velociraptoridae
>         C  Dromaeosauridae
>         4  Pl. Sinornithosaurus
>         ?  Pl. Unenlagia
>         5  Pl. Microraptor
>         6  Pl. Rahonavis
>         7  Archaeopterygidae
>         8  Yandangornithidae
>         9  Pl. Sapeornis
>        10  Confuciusornithidae
>        11  Enantiornithidae
>        12  {{Euornithes}} (Patago., etc.)
> _1_ Patagopterygiformes
> 2  Hesperornithiformes
> 3  Plesion Apsaravis
> 4  Ichthyornithiformes
> 5  Tinamiformes
> _a_ Struthioniformes (ratites)
> 6  Galliformes
>      .....other neognath orders
>
> ***************************************
> NOTE:  I will be discussing the precise apomorphy-based definition of the
> new Aves in the days to come.  All suggestions are welcome.  And also note
> that I plan to add Plesion Bagaraatan once I decide the best place for it.
>
>
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