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RE: Willie Wonka and the New Papers



I raced through the posts on this topic after noting Mayr saying
"Recognition of Zygodactylidae as the possible sister taxon of the
Passeriformes implies that stem group representatives of passerines already
existed by the early Eocene." - as if he didn't know about the Murgon
passerine specimens (SE Queensland, Australia, ~55 Ma). David M and Evelyn
S, at least, must have noticed this too.

Then saw Eike's footnote about diet-switching, which reminds me of an idea
that: it may be easier than you'd expect, because animals pick up bacteria
(etc.) capable of predigesting food items from the food itself. I don't know
if this has been published or discussed anywhere, but I've thought about it
before, and it appeals as (potentially) one of those 'behaviour-first'
evolutionary mechanisms that Lamarck would have approved (I had a zoology
lecturer once, Don Anderson at Sydney Uni, who liked that sort of thing and
thought Lamarck was misunderstood).

Favourite prey-switching example: Piranhas _Serrasalmus_, from floating
fruit (bobbing for 'apples' from underneath) to swimming vertebrates.  There
are old anecdotes of pythons eating mangoes, but this is either not
confirmed or not studied AFAIK.

Cheers,
John

-----------------------------------------------
Dr John D. Scanlon, FCD
Riversleigh Fossil Centre, Outback at Isa
riversleigh@outbackatisa.com.au
http://tinyurl.com/f2rby
 
"Get this $%#@* python off me!", said Tom laocoonically.*

*(PS - it's been suggested to me that this joke is excessively obscure and
might be found offensive, anybody got an opinion?)

-----Original Message-----
From: evelyn sobielski [mailto:koreke77@yahoo.de] 
Sent: 18 March, 2008 12:09 PM
To: dinosaur@usc.edu
Subject: Re: Willie Wonka and the New Papers


> Of the four big clades of passeriforms, one
> (possibly the sister-group of 
> all the rest) is restricted to NZ, one comes from
> South America, one comes 
> from Australia, and the last is paleotropical except
> for *Sapayoa aenigma* 
> which lives in SA, again pointing to Outer Gondwana
> as the place of origin. 
> And that's as far from Europe as you can get.
> 
> I didn't say "that makes it impossible"; it doesn't.
> But it requires an 
> explanation. 

How about: Origin of Passeriformes lies *in the
colonization* of Australia, from Borneo (or generally,
W Indonesia which was more or less contiguous land
then). Apparently W Wallacea was not yet overwater,
and the ocean-crossing distance was considerable.
There was habitat but scant competition in Australia;
from there ->(Antarctica->)NZ, ->SE
Asia/India->Madagascar/Africa->(Sapayoa ancestors)SAm,
->Asia (pittas), ->Antarctica->SAm->NAm, and radiating
in Australia-Melanesia and then -> Eurasia etc.

Plus the earliest European passeriforms, of which
almost all seem to have been additional very basal
lineages, "Old World" suboscines, or corvoideans and
sylvioideans.

Origin of Zygodactylidae then would be the SE Asian
mainland population of the LCA, which coast-hugging
south of the Alpides for the most part spread ENE to
Europe.

This would also tie in with the abundant record of
what seems to be "near passerines" from mid-Paleocene
Europe. The entire bulk - rollers, kingfishers,
woodpeckers, barbets, puffbirds, etc, even trogons and
toucans, looks like a generally Eurasia-centered
radiation if one considers the stem lineages which are
far more frequent in Europe than in NAm (the fossil
record is rather good on these two continents for the
time in question), piculet phylogeography etc. 

We don't know anything between Zygodactylidae,
_Neanis_ (if that is indeed so close), Early Oligocene
woodpeckers, and the 2 Murgon bones. I think as
outlined above, it requires the least "ghost" record,
which we do not seem to be able to get around either
way at present.


Incidentially the emerging "near passerine" clade
shows a number of traits and properties in morphology
and ecology more frequently than other birds. In
particular, forefoot anatomy seems to have been
exceptionally plastic.

But also a strong tendency to be: 
* short-tailed and smallish
* fairly round-winged and better able to maneuver in
confined space than to fly long distances
* perchers on branches rather than skulkers, climbers,
runners etc
* inhabitants of subtropical to tropical habitat with
plenty of trees
* resident to vagrant; though a capability to evolve
migration is present, it is less often realized than
simply adapting to colder climate and staying resident
* generally sluggish but active when feeding - not
like e.g. crown Galloanserae which generally move
about a lot but do not "go after" food but rather
"happen" across it
* merrily mixing frugivory and decidedly carnivorous
habits, as the latter being active hunters of
everything they can overpower (large invertebrates and
small vertebrates), without any easily recognizable
phylogenetic pattern[*]
* cavity-nesting
* seasonally monogamous or perhaps permanently
monogamous
* diurnal
* more dependent on eyesight than on hearing in
interaction with the environment (complex
vocalizations are limited, but visual signals are
widespread and important in speciation).

Especially the Passeriformes stand apart. But even
here, the more basal a lineage diverged, the more
frequent are these traits in it.


Regards,

Eike

[*] This is odd because a trophic switch from
frugivory (especially strict frugivory as present in
several lineages here) to mesocarnivory and vice versa
is not at all trivial metabolically; the genetic
changes required for it to work might be more complex
than for changing dactyly (if the nervous system is
very self-organizing). It would be interesting to give
it a closer look; there might be a phylogenetic pattern.


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