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Re: Dinosaurs Decoded

2009/10/12 David Marjanovic <david.marjanovic@gmx.at>:
>>  As far as I'm concerned, the hypothesis that _Dracorex_ and
>>  _Stygimoloch_ are j[...]uvenile _Pachycephalosaurus_ is complete and
>>  utter bunk. Bakker gives a good rebuttal here:
>>  http://scienceblogs.com/laelaps/2008/04/paleontological_profiles_rober.php
> "Good rebuttal"? The first half is nothing but an argument from personal
> incredulity(*),

That's not a fair characterisation of Bakker's argument.  It's
actually an argument from lack of any extant analogue, which is a much
more compelling thing.  (*cough* Taylor et al. 2009 *cough*).  It
doesn't mean he's right, necessarily, but his point at least deserves
more of a rebuttal than being written off as Personal Incredulity.

For example, if someone can show an extant animal that _does_ reverse
its ornamentation trajectory during ontogeny, then Bakker's objection
would be undermined.

> Besides, Bakker doesn't seem to know what "theory" means. Calling the growth
> series idea a hypothesis (as you did), or even a speculation, would have
> been much more appropriate ("speculation" would have had the added bonus,
> for Bakker, of sounding somewhat derogative, even though it's a technical
> term like any other); a theory is something big and overarching that
> explains a large chunk of "life, the universe, and everything" all at once,
> like the theory of evolution, the theory of general relativity, or the
> theory of quantum electrodynamics.

Please.  This is an article where Bakker refers to "butt-head
dinosaurs" rather than "pachycephalosaurs".  It seems pretty clear
here that he's writing down to a non-technical audience.  I am sure he
knows exactly what the word "theory" means in the mouths of
professional scientists; but he also knows what it means in the mouths
of the other 99.9% of the population, which is who he's talking to.
Now you may say that this is "dumbing down" and a mistake; I won't
necessarily disagree.  But let's not pretend that Bakker doesn't know
what he's doing.

So far as I know, the jury is still out -- far out -- on Horner's
pachycephalosaurian growth-series hypothesis.  He gave a pretty good
presentation on it in 2007, and another that touched on it in 2009;
that, unless someone can fill me in on something I missed, is where
the matter stands.  Until he publishes something, it's just another
idea that's out there waiting to be tested.

(Someone pointed in a question after Horner's Bristol talk that the
idea of Dracorex as a juvenile Stygymoloch seems easier to buy -- it's
going on from there to the relatively unornamented Pachycephalosaurus
that strains things.)