The geneticists who brought them forth from the past using their DNA, had made the Tyrants weak. It was done as a safety measure as they had the most powerful bite of any land animal, possibly of any animal. Numerous times, their first Rex had successfully escaped its enclosures by biting through the iron gates. It had to be culled. The geneticists toned their bite force down, taking away their primary weapon.
But after the big desertion of the Isla Sorna facility, they had released all the animals into the wild. Only the strongest would survive. But the Spinosaur was an anomaly. It wasn't a full blood Spino. The insect the geneticists had gotten the Spinosaur DNA from, had bitten two animals, two super predators, creating a hybrid. Though it appeared to be a Spinosaur, it had Carcharodontosaurus DNA, giving it powerful, flesh ripping jaws and a more robust and muscular body, perfectly suited to kill other gigantic animals.
The Spinosaurus growled, it could smell the other predator, it was close. It walked forward, toward a clearing in the distance, it could see vultures and pterasaurs gliding in a wide circle, something lay dead in the grassy field. The Spinosaur was either up wind or the flesh of the dead animal had not begun rotting for it could no longer smell nothing. It stopped, toward the center of the plain it could see an enormous therapod tearing at a dead Parasaurolophus.
Though most of the predators on the island had designated territories and would avoid any possible rivalry between them, the Spinosaur was different. It had decided the entire Island was its territory and all threats to this empire had to be exterminated. It had decided to move against the Tyrannosaurs first, it had already killed four, and there may be one left.
But the dinosaur it was gazing upon now, wasn't a Tyrannosaur. It was larger than any of the Tyrants it had smouted before, its skin was greyish blue, its underbelly white. It weighed its options, and decided it would kill this thing, whatever it was, right now. The massive Spinosaurus stepped out from the trees, it sent blood into its spine, making the sail turn red, it narrowed its green eyes and roared.
The unknown dinosaur stopped, hearing the roar, it slowly lifted its head, looking in all directions. It made a low growl, blood pouring off its giant jaws, its teeth sharp and serrated, perfect for slicing through flesh. It stood up, lifting its head in a proud manner. Then it noticed the animal that had made the roar.
The Spinosaur's eyes widened. This was no rival it had encountered before, this was different. It prepared its body for the coming battle.
Miles away, on the other side of the island, a large cage had been torn open. The rusted and bent sign above the huge enclosure read 'Giganotosaurus carilinii'.