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RE: Ah ha! That's where therizinosaurs came from



Mickey wrote (quoting GS Paul):

<As for your statement "What the cladistics would have us believe is that
 all these predatory, omnivorous and herbivorous early fliers were 
flitting about in the later half of the Mesozoic yet for some magical 
reason were never spinning off reflightless forms that show up in the 
fossil record. Really, that's what the cladograms want us to take 
seriously", that's rather unfair.  I'm a card-carrying cladist and I'm 
just fine with eudromaeosaurs coming from flying microraptorian-like 
ancestors, derived troodontids coming from flying Anchiornis-like 
ancestors, oviraptorosaurs coming from flying ancestors which may be 
omnivoropterygids, flightless unenlagiines coming from flying 
Rahonavis-like ancestors, Yandangornis coming from flying 
jeholornithid-like ancestors, as well as possibly independently 
flightless taxa like Mahakala and Tianyuraptor.  Whether flight evolved 
as far back as alvarezsauroids, therizinosaurs or ornithomimosaurs I'm 
successively less confidant of.>

  It should be noted that the presence at the base of *Deinonychosauria* of 
taxa with elongated forelimbs, "derived" pectoral girdles, but deriving into 
larger-bodied and apparently less arboreal/scansorial/volant taxa is found in 
the TWG analyses. In other words, the only issue here is the position of 
*Archaeopteryx lithographica*. Here, the "neoflightless" argument wishes to 
place birds into paraphyletic arrangements with various groups of apparently 
non-avian taxa as their descendants. This is, to a degree, an attempt to 
reconcile the appearance in the fossil record with the taxonomic arrangement 
being proposed, and it places the fossil record as the _a priori_ determinant 
for phylogeny, rather than a product of missing information. This is one of the 
reasons why sampling completeness matters to some, despite the Jiufotang and 
Liaoning Formations continually popping out new taxa, or the Tuchengzi 
Formation below it, or the Tiaojishan (=Lianqi) Formation apparently below that 
(I'll leave out recognition biases on taxa, here, or the tendency of 
researchers to name new taxa rather than withhold their taxonomic assignments, 
or the need to publish being forced as some record of achievement or value, 
which again just forces the previous issue).

  We (and by this, I mean folks like Tim Williams, Mickey Mortimer, etc.) 
already regard may clades deriving from basally flight-plausible taxa, and yet 
this still allows us to conform to the cladistic methodology for phylogeny 
reconstruction, and which has yet to actually contradict this arrangement (one 
reason why some anti-cladists such as the BAND camp favor the arbitrary and 
subjective typologic "method" instead: "If it looks like a duck, it is!").

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)