it really depends, if its a long drawn out fight, the T-rex, but if the rex is getting a nice cool sip of water.....super croc is gonna kick her @$$...
Crenshaw
PS: Her, because i vageuly remember something about female rexes being bigger then male ones...
Usually crocs grab and roll, either killing their prey in the intitial snap, or drowning them they don't usually knock down drag out fight. Super croc was probably the same, so it would not be much of a fight. Either the coc got ahold and took it down, or it missed and the Rex escaped.
I think it would depend on the terrain. on dry land, Rex FTW. Near water with the element of surprise its Croc FTW. Don't crocs rely on drowning their prey more so than biting them to death? The water would need to be pretty deep.
I'm going to go with t-rex since he's about double the mass, 16,000 lbs compared to 8,000 lbs. Crocs don't normally take on animals twice their size. I've also seen video of lions and tigers killing crocs since these predators can get behind their neck fairly easily. I'm guessing there could have been the occational upset, but my money is with the big guy.
I have even seen some leopards kill a croc. Amazing to watch.
Id say if T-Rex was in shallow water the Sarcosuchus could crab a hold of the T-Rex's neck & death roll etc It would most likely snap its neck &/or drowned it.