Spinosaurus could be taller and longer than trex, it can swim in water with its snout, eyes and sail sticking out like an alligator but it can't submerge since that'd be pretty complex.

Size: 18 feet tall at the head, 16 feet tall at the hip and 23 feet tall at the sail at 55 feet long.

attack animations: For small prey it just snaps them into its mouth quickly and then yanks its head back to swallow sort of like a pelican would do. It'd have a special animation for the trex where it grabs trex neck with its claws and mouth and bends it till it snaps like it did to the buck in JP3.

Health: spino could have 2x the trex health.