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RE: Greg Paul is right (again); or "Archie's not a birdy"



  Not just because this is about a clade I've been working on, but idea that 
one doesn't perform a cladistic analysis becuase other peoples' treatment has 
found short-tailed taxa at the base of it is hogwash. Basing your general 
dislike of cladistic analysis because the _result_ "seems" wrong is placing a 
primacy on the belief of a result, and the quality of the analysis is rated 
according to its ability to affirm that belief. Because of the rules of this 
list, I will not mention where this is _very_ relevant, but I can assure Greg 
that he is familiar with Phil Senter's work in this sector, and this should be 
telling on the subject of his lack of appreciation for cladistic analysis. It's 
a rut, I tell you, and cladistic analysis is supportive of the strong 
scientific principle that increasing and refining data input increases the 
quality of data output. If you hold on to an opinion while data changes around 
you, you do [big-S] Science no service.

  On a more specific issue: The shape of the tail is irrelevant: virtually all 
basal oviraptorosaurs
 have MORE caudal vertebrae than *Archaeopteryx lithographica*, whereas 
various oviraptorids have even MORE caudal vertebrae than than, but most
 have a generally high number compared to most typical basal birds. Despite 
this, the tail in *Archaeopteryx lithographica* is lengthened apomorphically 
more than in virtually all other taxa relative to its tail length, a feature 
found (convergently, apparently) in *Shenzhouraptor sinensis* (=*Jeholornis 
prima*); it is confusing to conflate tail length and vertebral number when 
ignoring vertebral length is also a factor, and one that doesn't make sense 
without elongation of a basally short tail. Not to spoil things too much, but I 
will note that there are a few details of the oviraptorosaur tail anatomy that 
imply not just extreme tail shortening but also caudal vertebral duplication 
and an increase in count after the fact of shortening. This is merely recovered 
by placing (noncladistically) oviraptorids next to caenagnathids next to 
caudipterids next to "protarchaeopterygids." The trend and tail morphology 
shows the tail getting progressively less "bird-like" and increasing vertebral 
count. This is also seemingly correlated to size.

  And it's that last bit that I think is screwing a lot of people up on their 
expectations: Virtually all of these Early Cretaceous/Late Jurassic "birdy" 
taxa are small, gracile, seemingly arboreal or scansorial taxa with long-ish 
arms and triangular skulls with pointy little snouts and huge eye balls. We are 
almost assured that they would have had very similar ecomorphologies, were 
competitive replacements to one another through time, and should we gain the 
level of resolution we seek as in Fowler and Horner in the Hell Creek or 
Currie, Eberth et al. in the Dinosaur Park Formation, we will likely see this 
to be far more intricate than just a phylogeny of "neoflightless" taxa: some of 
them may never have had flight in their lineage, because those adaptations are 
useful for other things, too. 

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)


----------------------------------------
> Date: Thu, 28 Jul 2011 17:40:37 -0400
> From: GSP1954@aol.com
> To: dinosaur@usc.edu
> Subject: Re: Greg Paul is right (again); or "Archie's not a birdy"
>
>
> In a message dated 7/28/11 4:06:24 PM, david.marjanovic@gmx.at writes:
>
> << [GP] suggested in the Field Guide that oviraptorosaurs are secondarily
> flightless descendents of omnivoropterygids, although that requires
> considerable
> pelvic reversals.
>
> [DM] Stay tuned.
> >>
>
> While I'm on this, it is a pecuilar feature of the main Xu et al cladogram
> that at the base the taxa are short tailed Early Cretaceous taxa, which
> implies that the Late Jurassic archaeopterygids reevolved long tails. Me very,
> very doubtful about that, its a real stretch. This sort of thing is one
> reason I won't do cladograms since I would not be willing to publish what is 
> very
> probably an errant result like that. I mean really, I'd be embarrassed and
> would have to spend a good chunk of the paper ranting about how its probably
> not true. I'm not kidding. What would I do if a cladogram I ran came up
> with results that did just not appear to make sense as they fairly often do,
> publish it and call it a load of crap? Best avoid such awkward situations.
> Anyhow, it is much more likely that deinonychosaurs were basal to the short
> tailed dinobirds, with LJ archaeopterygids being basal to later 
> deinonychosaurs
> that were either better adapted for flight or secondarily flightless. Then
> came along the short tailed fliers which spun off short tailed nonfliers.
> Just makes more sense to me. If so then the beginnings of dinoavian flight was
> pretty predaceous, and then went more herbivorous. Call me screwy for
> prefering phylogenetic-temporal logic and instinct over computer character
> crunching, but that's what got me to were I am today so I don't mind being 
> crazy -
> like a fox.
>
> GSPaul
>
> </HTML>