RE: Livezey and Zusi's big bird morph analysis and Archaeopteryx 10

[evelyn sobielski <koreke77@yahoo.de>]

--- Michael Mortimer <mickey_mortimer111@msn.com>
schrieb:

> Finally, the Livezey and Zusi's long-awaited
> morphological analysis of Aves 
> is published!  And the pdf is freely available.
> http://www.blackwell-synergy.com/toc/zoj/149/1
> 
> Livezey and Zusi, 2007. Higher-order phylogeny of
> modern birds (Theropoda, 
> Aves: Neornithes) based on comparative anatomy. II.
> Analysis and discussion. 
> Zoological Journal of the Linnean Society. 149 (1),
> 1-95.
> 
> "Thirty-five outgroup taxa encompassing Crocodylia,
> predominately
> theropod Dinosauria, and selected Mesozoic birds
> were used to root the 
> trees. Based on study of specimens
> and the literature, 2954 morphological characters
> were defined; these 
> characters have been described in a companion
> work, approximately one-third of which were
> multistate (i.e. comprised at 
> least three states), and states within more
> than one-half of these multistate characters were
> ordered for analysis."
> 
> 2954 characters!!!!???  Have I gone to Heaven? ;) 
> From my preliminary 
> skimming of pages, note that even this huge of a
> morphological analysis 
> seems to be corrupted by convergent taxa grouping
> together (grebes and 
> loons, etc.), if molecular analyses are anything to
> judge by.  But damn.... 
> this is THE morphological analysis of living birds.

No approach seems to be devoid of gouping convergent
taxa.
Take for example fig. 8A (I must say that I find
Fain/Houde - except that the Metaves might be an
artifact - seems to resolve the issue most sensibly by
and large). It looks legit overall; the grebe-penguin
clade is notable (as is is a better suggestion than
most) but the hummingbirds are obviously misplaced.
The Slack study (fig. 9B) essentially reproduces
Fain/Houde, but with the "diurnal raptors" unresolved
- given the sheer amount of chromosomal rearrangements
present in Accipitridae, one could actually ponder
whether it is wise to include them at all - and in
that the passerid clade is basal which the fossil data
available suggests it's most certainly not.

As regards their phylogeny:
(Isn't their use of Neoaves fairly unusual?)

Group B is generally well-supported, though the timing
of the galliform/anseriform split is debatable, as is
ratite phylogeny... the ratite morphotype, however
similar it may look, is certainly a (partly) neotenic
homoplasy, with moa probably becoming flightless first
and ostriches last. Note that the phylogeny of moa vs
kiwis does not allow conclusions about where they
became flightless; ecomorphologically, the small size
of kiwis suggests that moa had already occupied the
megafaunal niche when kiwis became flightless.

Group C is a good candidate for being genuine by and
large, but I wouldn't bet anything on the internal
grouping and inclusiveness.

Group D, neither placement nor position are all too
certain, but then again, other models are just as
shaky, and the respective placement of charadirrforms
+ buttonquails and rails has not been tested
thoroughly via molecular analysis. I *think* the
traditional Gruiformes fall outside Fain & houde's
charadriiform clade (which is basal to the
non-Galloanseres neognaths in their analysis... the
fossil record is equivocal, there are simply too many
generalized "graculavids" which may belong into either
groups C or D  as per this study).

Group E, I wouldn't give a cent on internal phylogeny
but overall, this is as good (or bad) a solution as
any. It lacks the most flagrant problems sometimes
encountered.

Groups F and G: yes, there is general agreement that
that's it, or at least something very similar.
Position of some group E lineages in respect to group
F is debatable (i.e., what exactly is "near
passerines"?).

As for the subtrees, I'll save that until need arises
to discuss it in detail.
 
> And just to make this issue even better, we get an
> osteology of the new 
> Archaeopteryx specimen.
> 
> Mayr, Pohl, Hartman and Peters, 2007. The tenth
> skeletal specimen of 
> Archaeopteryx. Zoological Journal of the Linnean
> Society. 149 (1), 97&#8211;116.

Does it contain a phylogenetic analysis with more taxa
than the preliminary study ("A
well-preserved...theropod features") - on both sides
of Archie? I'm most eagerly awaiting that. Their
placement of Confuciusornis in the Microraptor clade
is possibly as large a revolution as was the intial
discovery of Archie (for one thing, the degree of
specialization in C. vs M. is intriguing. For another
thing, it would indicate Gauthier's, not Sereno's
definition of Aves is more meaningful; and that
(gasp!) Archie might be excluded from the Aves
altogether at some future date... we have learnt to
think about it as "bird", because the fossil record,
until 10 years ago, has indicated that it was just
that. But today, there is no reason to think of it as
anything but a paravian theropod incertae sedis. To
use it to define Aves in spite of the gap in the
fossil record spatially and temporally is sacrificing
consistency for tradition. "Bird", if the Mayr et al
study is worth anything, is a form taxon with no
phylogenetic merit if one includes the fossil record,
as implied by Barsbold 23 years ago when he started to
analyze his oviraptorosaurs with "avian" apomorphies.
I think we'll find the "bird" lineages to number more
than 2, possibly even more than 5, eventually, making
the discussion which "dinos" were really "birds" moot
but the discussion which Theropoda were Aves all the
more interesting. All that can be said is that
*several* lineages of theropods were exapted for
(par)avian flight to a high degree, and IMHO the
assumption that "birds" are monophyletic stretches the
evidence and analyses available today a bit far. The
message from the preliminary analysis of Archie #10 is
that either Confuciusornis or Archie were Aves - and
in fact, maybe neither! -, but not both, if Aves is to
stand for something meaningful at all in an
evolutionary context rather than an arbitrary
assemblage of theropods of which some took wing and
most didn't, and that Aves as per Sereno != "birds".

The implications are fairly extreme, I know. We need
more analyses, because an Eurasian (Laurasian?)
Oxfordian-to-Tithonian equivalent of the Jehol Biota
ain't forthcoming, or shouldn't be bet upon doing so
at least.

Regards,

Eike

PS: Is the character set and matrix for Livezey/Zusi
available separately? And for a completely unrelated
thing, when is somebody gonna do an ancient mtDNA
analysis of the (AFAIK) only bird ever named in honor
of Zusi (Heliangelus zusii)? Whether valid or not, the
results will be most noteworthy.


                
___________________________________________________________ 
Telefonate ohne weitere Kosten vom PC zum PC: http://messenger.yahoo.de