Re : Ouranosaurus' sail

[Silvio Renesto <silvio.renesto@uninsubria.it>]

At 05.43 11/06/2003 -0400, you wrote:
> And why not the contrary, as a strategy for the carnivore, to approach 
> planteaters within a reasonnable distance before attacking? (as already 
> suggested onlist IIRC)
> Cheers,
> Jean-Michel


Good point,
Since it is still hot and my brain doesn't want to work on usual stuff,  I 
try to go on with the guess and explain better my point of view:
I was guessing that spinosaurids preyed close to/in rivers (some large fish 
or other aquatic ad semi aquatic vertebrates) and rarely on Ouranosaurus. 
Otherwise it would have been difficult for the prey to avoid the similar 
shaped predator and your idea (spinosaurs are the mimics) becomes the right 
one.
If spinosaurs were not the main predators, the mimicry in ouranosaurs was 
instead a device against other, non spinosaurid predators, small enough to 
feel that dealing with a spinosaur would have meant business for them. Who 
knows, might the spinosaurid claw  have been a deterrent even for a 
carcharodontosaurid ?
Before shutting up, I wonder:
Is there today a similar example of "reversed mimicry" that is, a predator 
that looks like a prey to get closer to it with more ease?
Putting aside insects, where I think you can find nearly to everything, 
does it happens among terrestrial/flying vertebrates?
Within snakes both the deadly coral snake Micrurus and the inoffensive milk 
snake Lampropeltis represent mimics of a moderately poisonous genus. In 
both cases, however the message is directed to a potential attacker (I am 
dangerous, go away) not to a prey.
Here in Italy the small non-poisonous snake Coronella mimics the deadly 
adder Vipera in colour pattern and, when threatened, it even flattens its 
oval colubrid head to form a triangular adder-like head (it usually reveals 
to be a  bad idea when humans are involved...)
Back to a cold fruit juice and more basal diapsids now...
Cheers,

                                                                Silvio 
Renesto

_
A good traveler leaves no tracks.
Good speech lacks faultfinding.
A good counter needs no calculator.
A well-shut door will stay closed without a latch.
Skillful fastening will stay tied without knots.

                                (Lao Tzu)


Prof. Silvio Renesto
Department of Structural and Functional Biology
Università degli Studi dell'Insubria
via Dunant 3
21100 Varese
Tel. +39-0332-421560

e-mail: silvio.renesto@uninsubria.it