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VULTURES AND MUSOPHAGIDS



Had some format problems with hotmail email, lets see if it improved...

<<The idea that all the taxa Nick mentioned form a single 'basal South
American landbird assemblage' is essentially a Storrs Olson (1985)
theory. Olson suggested that hoatzins, which he regards as
generalised landbirds perhaps well suited as ancestors to later
'basal landbirds' (much the same as _Foro_), could be ancestral to
the seriema-phorusrhacoid clade. Both groups do share an unusual
lateral bowing of the third metacarpal, and Cecile Mourer-Chauvire
has also used this character to support a hoatzin-seriema link. If
this is true, it's cool, for (as I've discussed here before) it might
suggest that free, clawed fingers are primitive for this clade. Take
that with a ***big*** pinch of sodium chloride.>>

The laterally bowed minor metacarpal was basically the whole of Olson's evidence for this theory as well (see his diagram in _The Fossil Record of Birds_). Olson has expanded this, in his _Foro_ paper, to include cuculiforms and musophagids and perhaps falconiforms (just accipiterids if I remember correctly) in some weird way that I don't quite understand. Basically, Olson classified _Foro_ as a cuculiform, but described its mosaic nature (which I don't quite see, I think its a basal opisthocomid) with musophagids and falconiforms. Olson's 'landbird' trees, especially his 'basal landbird' one, are great messes of old hypotheses and new interpretations of Olson's doing.

<<Meanwhile, Olson (1985) also suggests that touracos and falcons are similar in osteology and might therefore be related, that caracaras
might be related to the hoatzin-seriema group, and that touracos may
belong in the basal landbird assemblage (and therefore be related to
hoatzins and seriemas).>>


If I remember correctly, the extent of Olson's comparisons was "they look similiar in osteology", something I should check. I don't remember many characters being thrown around. Anyway, I think that the syringeal evidence presented by Griffiths (1994) for monophyly of falconiforms, in/excluding vulturids, is very strong.

<<A touraco-seriema affinity has most recently been supported by Robert Chandler based on some morphological and molecular characters - he covered this at SVP 1997 and has a paper in
prep. (or in press? Matt?). Chandler proposed that vulturids
(=cathartids) were the sister-group to a touraco + seriema +phorusrhacoid clade.>>


Last time I heard, I thought it was in review. Don't know of its statis now.

<<OK.. now for the speech about empirical evidence. Olson's
suggestions, and his hypothesis that all of these so-called basal
landbirds are interrelated, is an INTUITIVE scenario. It is not based
on cold hard facts or detailed analytical studies - indeed, no
supporting details have yet been provided for any aspect of the scenario (excepting the metacarpal character cited above) - and
essentially the suggestions are simply ideas based on gestalt
similarities. For example, Olson (1985) literally states pretty much
that, WRT touracos and falcons, "they look similar, so they are
probably related" (NOT a direct quote!!!). Therefore, the ideas
should be regarded simply as interesting speculations that require
testing. Few workers working on the higher-level systematics of
neornithine birds would accept that they probably do represent
reality (that's your cue Gareth..).>>


I must second Darren's observations and refer inquistive readers to Livezey (1997) for an excellent discussion of intuitive vs. cladist scenarios in avian phylogeny. Olson has published some very well-worked out phylogenies (such as his flamingo-recurvirostrid paper) but the majority of his proof in his 1985 paper rests on vague similiarities that are terribly selective (i.e., his consideration that leptostomids are close to the ancestry of owls because of their tarsometasal structure). There is more evidence for an ancient civilization in the Mars Cydonia locale than there is for many of Olson's musings. (This is not to take anything away from Olson, who is a great worker, but sometimes he presents ideas without evidence).

Anyway, in regards to Ron's statement that most workers think that vulturids are derived ciconiids is not really true. Yes, Sibley and Alquist have presented much molecular evidence and it is generally accepted that vulturids are storks, but not everyone is willing to say so. Cracraft has been rather cautious on this in his papers (unlike his grouping of owls with falconiforms; other than vulturids in his phylogeny). Griffiths has presented three syringeal characters (taken from a select group of birds) that support a vulturid-falconiform clade (one of the characters is found in an owl however). The debate is still open.

Matt Troutman
m_troutman@hotmail.com


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