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Re: Dinosaurian biology and sexual selection

n Fri, Oct 29, 2010 at 4:45 AM,  <bh480@scn.org> wrote:
> From: Ben Creisler
> bh480@scn.org
> In case this new paper has not been mentioned yet:
>> K. Padian & J. R. Horner (2010)
>> The definition of sexual selection and its implications
>> for dinosaurian biology.
>> Journal of Zoology (advance online publication)

>It is also worth noting that Knell and Sampson have written a reply to
>that paper in the same journal:

No. The Knell and Sampson rebuttal is to:

Padian, K. & Horner, J. (2010a). The evolution of ââbizarre structuresââ in 
dinosaurs: biomechanics, 

sexual selection, social selection, or species recognition? J. Zool. 283 
(Online DOI: 10.1111/j.1469-7998.2010.00719.x.)

The upcoming Padian/Horner (2010b) paper on sexual selection points out the 
differences between sexual slelection as originally defined, and its current 
usage, and how this changes the way we interpret dinosaurs.

It's interesting that Knell and Sampson do not use the new term presented by 
Padian and Horner (2010a): "social signaling". Instead they use the old term 
"species recognition", which I agree has some inherent interpretation problems.

The reply also makes some interesting diversions from the usual 
cladogenesis-driven allopatry models of Sampson et al. 

The social signaling hypothesis actually makes a lot of sense, but I think you 
really have to use a high-resolution record to test it. You also need more up 
date phylogeny, and an understanding of when cladogenesis actually happens, and 
the potential roles of phylogenetic inertia. 

It is not made clear why, if these structures are for sexual display, in 
ceratopsids they change so significantly through ontogeny: surely they would 
just start out with small horns, then get bigger (more like hadrosaurs). Why 
change the orientation? downsize/resorption? none of this is accounted for by 
the sexual selection only hypothesis.