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RE: Horner's Pachy Lumpin' - Your Thoughts?



Actually, the burden of proof is on Horner to convince us about the
relevance of the histological data that they present and that the data
really show what he (they) says it shows, and not really for others to
debunk him (although this is always welcome and indeed should be done),
especially given the unique nature of the mechanisms they present -
something that will require pretty strong evidence, frankly, to establish.
I have not been overwhelmed by his (their) efforts but am happy to see their
arguments continue to develop in the face of such amazingly low sample
sizes, something that is the real villain here, and will be just as happy if
they do indeed turn out to be correct -ish (nothing ever seems to come out
exactly as early models suggest). IMHO They certainly have not been
particularly effective in other areas (e.g. ruling out non-display agnostic
behavior). A lot of the various types of "evidence" that have been thrown
around for these discussions in various forums has been pretty to amazingly
thin, frankly, including an incredible overdependence on relative size
issues of the skulls as being all that useful given the small number of
skulls and classic reptile/dinosaur growth patterns. I frankly found the
discussions of these size issues in their SVP talks to be pretty simplistic
and, frankly, awful from the standpoint of being a morphometrician. Been
working too long hours to re-review them in the paper recently but don't
remember them to be developed all that much better there. Further, we must
remember that quantification and rigor has never been Jack's strong point in
his research - just remember the T. rex eye size fiasco that should never
have lasted more than a couple hours given how easy it was to falsify with
just a simple bivariate plot (hey Tom!) and that should have been the first
thing done by Jack before he opened his mouth. I don't have a horse in this
race and basically could care less if Draco ends up canned, just, as has
always been the case with Horner's arguments about pachys, we must all
remember they seem to do some unique things in the way their skulls grow
(here the hat off to Jack and Mark, et al.) and it is ALWAYS difficult to
explain unique patterns without a long and detailed AND rigorous series of
discussions. This may be a good start and it is indeed a service to the
evolution of our ideas that Jack et al. have done such nicely detailed work.
Given the amazing increase in the number of pachy domes and skulls since I
first worked on them in the 1970's, I have hopes we will someday have a real
good sample size to do more than the limited work possible right now. But
let's not assume Horner et al. have explained everything and the full burden
has now shifted to other models, the game is pretty wide open right now and
everyone is fair game and in need of continuing to develop much more
support.


Ralph Chapman


-----Original Message-----
From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf Of
Williams, Scott
Sent: Friday, January 08, 2010 12:30 PM
To: dinosaur@usc.edu
Subject: RE: Horner's Pachy Lumpin' - Your Thoughts?

Michael Erickson Wrote- 

---Poor choice of words on my part. I still, however, feel that the
cervical fusion may be important somehow; Horner still should have at
touched upon it and attempted to provide some sort of alternative
explanation, in my opinion. This disregard of potentially (or, in some
cases, quite obviously) important data has been a consistency of
Horner's for a long time. Rather than pinpoint conflicting data and
explain it, debunk it, or find an alternative explanation, Horner simply
pretends it isn't there, which tends to get annoying.

        **I find this amusing since I have yet to see any pausible
explanation or falsification of Horner's histologic evidence.  When
"draco" supporters have been asked about this, little or no explanation
is provided or the subject is switched.  From the SVP presentation and
the Horner and Goodwin paper it appears CLEAR that the squamosal nodes
in the specimens the Horner used are resorbing.  Also, overwhelming dome
histo evidence to show that the juveniles/subadults have vascular spongy
interior while adults are "solid"

Also the whole discussion of "Fusion" is arbitrary.  I read the Bakker
et al. 2006 paper and look at the figures and see clear suture lines,
which I intrepret as NOT fused.  I have read other papers on the
difference between open/unfused, closed and fused.  Brochu has his paper
on croc vert fusion and (IMO) fused vertebra show no suture lines.

And dismissing the drastic ontogenetic changes that a Cassowary goes
through is irresponsible.  The fact that this animal retains juvenile
cranial characters up to 60% its adult size is certainly an interesting
analog.  

Long and short is that those who want to see "draco" revived, need to
come up with a plausible and TESTABLE theory which refutes Horner and
Goodwin.  Otherwise what this amounts to is hand-waving and opinions.
As Dr. Holtz put it a few months ago...."PUB UP OR SHUT UP".  When, I
see some testable results in a peer reviewed journal then I'll put more
weight into some of this discussion.  Until then, Horner and Goodwin
have done their job well which is why their paper was published.  


Scott Williams
Burpee Museum