Canopus III was the third planet orbiting the star Canopus. This was the homeworld of a species of dinosaurs. The planet was known for its desert-like terrain. This planet was located several light years from Lactra VII.
Prior to stardate 5501, James T. Kirk visited Canopus III. During his visit, he saw the dinosaurs. In 2269, the crew of the USS Enterprise encountered a dinosaur in a desert environment on Lactra VII, that was very much like the dinosaurs native to Canopus III. Despite initially hypothesizing that similar environments prompt similar evolution in species, it was later determined that the beast was, in fact, transplanted to the planet by the Lactrans, who terraformed the desert terrain for the beast as part of their zoo exhibit. (TAS: "The Eye of the Beholder")
In 2293, the location of Canopus III in the Milky Way Galaxy was labeled in a star chart that was in Captain James T. Kirk's quarters aboard the USS Enterprise-A. (Star Trek VI: The Undiscovered Country, okudagram)