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Re: Long-necked stegosaur coming out in Proceedings B



Quoting Tim Williams <tijawi@yahoo.com>:
> 
> > "... two scenarios are possible."
> > 
> > "The first is that the long neck might have permitted it to
> > browse for foliage at a height not 
> > frequented by other prehistoric animals. The second is that
> > males and females might have found 
> > the trait appealing, so it evolved due to sexual selection.
> 
> 
> I would have suggested a third possibility (not the same as Dann's), which is
> that a longer neck would allow a better 'look-out' to scour the terrain for
> approaching predators.  Interestingly, this idea is implicitly contradicted
> by the paper:
> 
> "By contrast, the long neck of _Miragaia_ incurred a survival cost because it
> presented a greater predation target for medium to large-sized
> theropods..."
> 
> I'm not sure I understand this point, because surely a stegosaur like
> _Miragaia_ would confront an approaching predator tail-first (=
> 'thagomizer-first') rather than head-first.

I would also expect few predators to approach their prey head-on, since that's 
generally a good way to 
be spotted quickly by your prey. Even if they did try the direct approach, 
surely their prey would make 
some sort of attempt to turn around and move away before the predator got 
there. Either way, you'd 
expect a predator to be dealing with a stegosaur's hind quarters more often 
than not.

Perhaps a longer, more flexible neck made looking back at predators easier? The 
problem with having 
your main defensive weapons on your tail is that you have to turn your back on 
your enemies to use it. 
Being able to look backwards to aim your tail swipes might be an advantage.

-- 
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Dann Pigdon
GIS / Archaeologist              http://geo_cities.com/dannsdinosaurs
Melbourne, Australia             http://heretichides.soffiles.com
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