Sprawl, speed etc

[(veni, vidi, concreti) <martin@hpentccl.grenoble.hp.com>]

Sorry, I'm a bi lost with these sprawl/upright mixes/speeds/stances. Rob, I 
think, has said that sprawled front limbs add stability and a sprawl means an 
aniimal does not have to slow down in a turn, whereas an upright animal does 
not. Having spent a good deal of time on horsback (and being thrown off) I can 
assure you that an upright animal does not loose speed on a turn; it simply 
"changes foot" ie adjusts its pace to lead with the foot that is on the outside 
of the turn, leans over so that centrfugal forces (laymans term?) holds it in 
place on the turn, and carries on running/galloping/whatever. Equally it does 
not loose manoeuvrability; it uses a hind foot to pivot (and can do this so 
unexpectedly/fast that the rider falls off). 

I don't understand Rob's concept of "dune busting" at all. For an animal to 
survive on  soft surface it needs big big feet to stay _on top_ of that 
surface. 
The only reason I can see where a sprawl would help would be where the diameter 
of its feet got so large they would collide with each other if held under the 
body.

An aside............
As a layman, I find it difficult to understand sometimes why animal/(read dino) 
behaviour is seen as primitive/simple/unsophisticated. Surely _any_ animal 
which 
survives for successive generations (ie successfully) is de facto an exhibitor 
of extremely complex behaviour/adaptation in relation to its environment? 

ciao, martin