Reincarnated as a dinosaur

Once the main hero of this story, was an young adult. When he saved a child from getting hit by a car, he died. But Death, granted him a wish, he can chose as what he would like to be reincarnated as and he chose to be reincarnated as a Giganotosaurus. What he was asuming, was that he would be reincarnated in the past, as a dinosaur. But little does he know, what his new life would be like and what adventures he will have to face...