Re: dino mimicry

[Shaun Sinclair <ssinclai@gpu.srv.ualberta.ca>]

On Tue, 21 Feb 1995, Ralph Chapman wrote:

> Shaun asks why I don;t think theropods will fall for mimicry when birds
> do all the time. I must clarify, I assume they would indeed fall for
> mimicry, I just wasn't impressed with the level of mimicry implied here -
> I think the example is a bit far fetched and looks more effective as
> silhouettes than it would in real life. Consequently, I wonder how much
> the anky's would really look like a backward dinosaur but I'm willing to
> be convinced. It just seemed to be stretching things a bit. Maybe it
> works great at night. Hey, I'm easy. Ralph Chapman


I figured that there must have been something in the paper that would 
have produced some scepticism. Unfortunately, I have just found out that 
I will have to "order out" for a copy of the paper since the University 
of Alberta library stopped receiving this journal in 1991 (grumble grumble).

Speculatively speaking, perhaps ankylosaurs browsed specifically during 
those times when the silhouette was most effective (morning/evening)? They 
could have spent 
the hotter mid-day hours under the shelter of trees (assuming, of course, 
that they were open plains grazers). Or perhaps from a distance the 
effect was sufficient to cause some confusion among the approaching 
theropods. If the ankylosaurs were in the middle of an open area 
with little cover for the theropods, then a stealthy approach 
from behind would be the best way to get close enough for an 
attack. If the theropods are fooled enough that they circle 
around to the front of the animal (upwind?) that may be just the 
advantage that the ankylosaurs needed to be forewarned. Of course, the
"tail club" COULD be used as both a defensive weapon and a mimic device. 

Comments?

Shaun