WDRA question

[Brian Hathaway <hammeris1@att.net>]

"When Dinosaurs Roamed America" had a seen where and allosaur chomped a 
ceratosaur in an ambush.  My question is, although I have no doubt a hungry 
allosaur would take advantage of a situation that confronted it, how likely 
would this have been?  Today, most carnivores (lions, bears, etc.) typically 
don't feast on other carnivores but prefer the zebras/deer/etc. either from 
taste or nutritional value instincts.  How often have carnivore remnants (that 
aren't small juveniles) been found in tyrannosaur/etc. fossil stomachs?  
Wouldn't a larger and more tasty iguanodon been preferred?