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

RE: Several New Papers

--- "Jerry D. Harris" <jharris@dixie.edu> schrieb:

> Yeah, subject lines like that are boring and
> redundant and repetitive and 
> redundant...

...while the main body is most assuredly not. :)

> Ericson, P.G., Anderson, C.L., Britton, T.,
> Elzanowski, A., Johansson, U.S., 
> Källersjö, M., Ohlson, J.I., Parsons, T.J., Zuccon,
> D., and Mayr, G. 2006. 
> Diversification of Neoaves: integration of molecular
> sequence data and 
> fossils. Biology Letters 2(4):543-547. doi:
> 10.1098/rsbl.2006.0523.

Or here:

> phylogenetically well-documented fossils. Our study
> defines several 
> well-supported clades within Neoaves.

4 seem to be good in any case - Galloanseres,
Charadriiformes, "higher waterbirds" and "higher
landbirds". In fact, these 4 seem to be as definite
and rock-solid as anyone could tell at present.
Charadriiform divergence fairly likely before K/P,
initial radiation may have started. "higher
waterbird"/"higher landbird" split possibly before
K/P, but not well supported.

I remain utterly unconvinced about "Metaves"; I think
that considering them a paraphyletic, autapomorphic
grouping which may contain the odd small clade that is
for real is an alternative hitherto not explored to
satisfaction (it has not even been really explored in
the original Fain & Houde paper, in which the
"metavian" caprimulgiforms were paraphyletic in
respect to flamingos, and if *that* does not set one's
alarm bells ringing, I am at a loss to think of
anything that would...).

Basically, the Metaves are really supported by in/del
molecular characters, which may or may not arise more
than once. If one takes a look at how peculiar
unequivocal large-scale genomic autapomorphies look in
Aves - such as the accipitrid chromosome rearrangement
- I find the in/del characters used to prop up the
"Metaves" fairly poor as a synapomorphy. Far too easy
to evolve homoplasically.

In contrast, the "Coronaves" can be neatly separated
down into the 3 clades outlined above, all well
supported by non-molecular evidence. The large degree
by which the characters delimiting the supposed
non-galloanserine neognathe clades differ in producing
meaningful resolution (Family-level for Coronaves,
Superorder-level for Metaves) is highly suspect.

This being science after all, I'll just put it like
this: give me a good solid attempt to *falsify* the
Metaves-Coronaves dichotomy, and if that *fails*, I'll
think about it.

What is a bit disappointing is that the verdict on
ciconiiform (non-Sibley) and gruiform monophyly is
still out. Well, you can't have everything.

BTW, I remember through a haze (post-partying
reference checks should be avoided) something of
somebody somewhere allying Laornis with the
presbyornithids? A "gruiform" it is fairly certainly
not; the issue seems basically whether this
mega-"wader" known from one damaged tibiotarsus is
galloanserine or charadiiform in the light of the last
2 years' advances.

> Schweitzer, M.H., Wittmeyer, J.L., and Horner, J.R.
> 2006. Soft tissue and 
> cellular preservation in vertebrate skeletal
> elements from the Cretaceous to 
> the present. Proceedings of the Royal Society of
> London B. doi: 
> 10.1098/rspb.2006.3705.

I am awaiting the debate of this one, though I am not
keen on taking part in it.

> Dyke, G.J., Malakhov, D.V., and Chiappe, L.M. 2006.
> A re-analysis of the 
> marine bird Asiahesperornis from northern 
> Kazakhstan. Cretaceous Research 
> 27(6):947-953. doi: 10.1016/j.cretres.2006.05.001.

Hmmm. Need to get hands on this one. That they call it
a "hesperornithiform" and not a "probable", "putative"
or "suspected" one anymore sounds good. I wonder if
they threw out some mismatched material, as it was
done with Headonornis.

Asiahesperornis is not really exciting. Maastrichtian
hesperornithiforms are not of much use
phylogenetically as of now. Cenomanian or earlier ones
are needed - we can't even properly make sense of
Enaliornis at present for utter lack of something to
compare it to (I don't know, maybe Gansus could be
thrown in for a comparison. Can't do harm in any case.
Hesperornis did not just fall out of the skies just
so, but what it evolved out of is anyone's guess).



Der frühe Vogel fängt den Wurm. Hier gelangen Sie zum neuen Yahoo! Mail: