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Re: Metaves and Coronaves



----- Original Message -----
From: Peter Houde <phoude@nmsu.edu>
Date: Sun, 12 Dec 2004 07:19:43 +0000 (UTC)

This will have substantial implications for the interpretation
of the many fossils of superficially crane/trumpeter/seriema-like
terrestrial birds that have been attributed to "gruiformes".

Hey great. There are such confusing lots of those... :-)

Its not that we aren't interested in the biogeographic origins of Metaves or
that we've given up on trying to sort it out. The reality, however, is that
previous attempts to address avian biogeographic origins have been flawed by
questionable or patently incorrect hypotheses of phylogeny, and complete
reliance on the modern distributions of extant taxa.

Oh, sorry for having created this impression. The paper does get this point across pretty unambiguously.


I am quick to point out, though, that the vast majority of existing calibrations are
based on unverified hypotheses of biogeography and phylogeny,

As well as unverified hypotheses on other things! Two papers have calibrated the basal divergences of ratites and passeriforms by the divergences of moas respectively New Zealand wrens -- both of which were implicitely assumed to have always been incapable of flying over water, so said divergences were assumed to coincide with the date when NZ broke off the rest of Gondwana, in the middle of the Late Cretaceous. Urgh.


Pteroclidae was originally described as Pteroclididae but recently shown to be
grammatically incorrect. Refer to Sibley and Monroe and the taxonomy data
base at NCBI Entrez.

Oh.

I'll leave you with one closing thought. There is no doubt that birds have
experienced the sort of ecological shifts we propose within Metaves. They
must have because birds are monophyletic. The question is - how many times
has this happened? If extant birds were truly representative of all the
extinct intermediate forms between these ecological shifts, then parsimony
would be a direct arbiter of phylogeny. Hence, Cracraft united loons, grebes,
and Hesperornithiformes.

IMHO this was not a problem of parsimony, but an artifact of the teeny tiny data matrices that were (due to computer power...) common at that time (and are still the norm in areas like metazoan phylogeny!). It was parsimony which soon removed the Hesperornithes from this grouping even in Cracraft's own work. When there are correlated characters (several that are all related to foot-propelled diving) in a matrix, and little else, the outcome is predictable. With a serious amount of characters and taxa, let alone the huge amount of characters and taxa that Livezey & Zusi are compiling, things are different.


Mayr even argued this recently from cladistic
analysis of morphological characters.

Yes, and he found *Juncitarsus* from Messel as the sistergroup of both together... just intuitively, that's a great place for The Flamingo-(Transitional) Shorebird Link (tm)... B-)


Has anyone out there compared the skeleton of a tropicbird with
that of a grebe lately? I have. Its less of a leap of faith than grebes-flamingos.

Wow...