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Re: Long-necked stegosaur coming out in Proceedings B

Don Ohmes wrote:

> I share and likely over-match your lack of anatomical
> knowledge, but would be surprised if they could not pivot
> effectively. I somehow doubt that "evasive action" was one
> of their talents, though.

It's not really a 'talent'.  Putting as much distance between yourself and a 
potential predator is just common sense.

> That said, an incremental difference in individual neck
> length will logically have a negligible effect on predator
> detection, which begs the question; what model of evolution
> can be used to create a long neck using enhanced
> predator-detection as a primary driver?

Homeotic transformations, such as those mediated by mutations in Hox genes, 
would allow whole segments (in this case, individual vertebrae) to be added 
wholesale to the cervical column.  A substantial increase in the total length 
of the neck would therefore occur quite rapidly.  So I don't necessarily agree 
that changes in neck length would "have a negligible effect on predator 
detection".  (You could also use your line of reasoning to argue that the same 
changes would have a negligible effect on foraging ability, because the 
proximate advantage in browse height would be fairly minimal per each 
incremental increase in neck length.)

Jason (pristichampsus@yahoo.com) wrote:

> While possible, I'd have to wonder why the rear end of the
> tail would be facing the predator, rather than the side.
> Most animals that use their tails in defense (crocodiles,
> monitor lizards, iguanas, etc) tend to present one side, or
> another to an attacker. This has the benefit of presenting a
> much larger target to the predator (which in this case,
> would be intimidating rather than inviting), and allowing
> for "better aim" of the tail. 

Actually, that's kinda what I had in mind: a stegosaur angled such that the 
tail is positioned to deliver maximum force against the attacker.  By 
"tail-first" I didn't literally mean that the stegosaur was positioned directly 
in front of the predator, like a two-way conga line.  :-)

Abyssal (saint_abyssal@yahoo.com) wrote

> Am I the only one who immediately thought of Bakker's
> "tripodal mid-height feeders" hypothesis from the Heresies
> when Miragaia was announced? It looks like he may have just
> been at least partially vindicated here. Did anyone ever
> investigate the Stegosaurs ability to rear up since Bakker
> proposed that? I remember there being some skepticism
> directed at the idea but never learned what really became of
> it.

Mateus &c do not seem to be much in favor of this idea - and they discuss why 
in the Supplementary Information (where _The Dinosaur Heresies_ is explicitly 

Hope that helps!