T-Rex was a carnivorous dinosaur from the Earth. On the moon M1M-316 live the descendants of dinosaurs that were taken from Earth several million years ago by the Ancients. And the moon is inhabited by dinosaur-like creature. Major John Sheppard's team encountered as they explored the moon. They explored the moon if it was a suitable place for the Alpha Site. (SGA: "The Siege, Part 1")