Siluria

Siluria was an unnamed planet featuring vegetation, gravity and an atmosphere similar to those of Earth circa the Cretaceous period. The Eleventh Doctor and Brian Williams founded Siluria as a home for terrestrial dinosaurs. The Silurians had spirited away from Earth mating pairs of myriad species of dinosaurs aboard an ark prior to the Cretaceous–Paleogene extinction event, c. 65.5 million BCE, depicted in Earthshock.

In 2367 CE, Brian and his son, Rory Williams, steered the ark away from its Earth-return trajectory and imminent destruction by the the Indian Space Agency. (DW: "Dinosaurs on a Spaceship")

Back on Earth, c. 2019-2020 CE, Brian posted to Rory and the latter's wife, Amy, a home-made postcard from Siluria, depicting dinosaurs, the TARDIS, and a hand-painted sign reading "Siluria".