T. rex appears to have only a limited range in North America and Asia, and is relatively short-lived. T. rex lived about 70 to 65 million years ago, during the late Cretaceous period. It was one of the last large dinosaurs. The T.Rex dinosaur was a bipedal carnivore with a massive skull Dinosaur taco saurus rex shirt, so to balance their weight they needed a long and heavy tail. T. rex grew much faster than typical reptiles today, and scientists estimate that it reached full size in about 20 years. By far the largest carnivore in its habitat, T. rex was most likely an apex predator, preying on raptors, herbivores such as ceratopsians and ankylosaurs, and possibly sauropods.