The hidden date for this stamp can be found along the right edge of the stamp.
It seems people everywhere are re-discovering a fascination with the "Age of Reptiles", a period in which the dinosaur was the dominant land creature. Canada Post Corporation is contributing to this phenomena with its issue of four stamps featuring three dinosaurs and one marine reptile to launch Stamp Month on October 1, 1993. The dinosaurs had 165 million years of domination of the earth from approximately 230 million to 65 million years ago. One theory of why the great beasts became extinct is because they could not adjust to drastic climatic changes brought about by a giant asteroid striking the Earth. Remains of dinosaurs have been found on all continents, with the first Canadian discovery being made at Morgan Creek, Saskatchewan in 1874 by geologists of Her Majesty's North American Boundary Commission. The famous "badlands" of Alberta yielded the most dinosaur finds in Canada to date. The third and heaviest dinosaur in this stamp set, the Cretaceous-period Styracosaurus, is generally known for its rhino-like horn and the unusually long spines in its frill. A huge creature, midway in size between a bull hippo and a bull elephant, it weighed about 4 metric tonnes and measured 5 meters in length. Males and females had different spines, and the Styracosaurus featured on the stamp displays the long backward pointing spines believed to denote a male specimen. Females, it is thought, had spines curving forward. Specimens of this dinosaur have been found in Alberta and Montana where they roamed about 76 million years ago. The Alberta species differs from that found in Montana in that it has a greater number of frill spines. Rolf Harder has designed all three stamps sets in the "Prehistoric Life in Canada" series. The choice of subjects was made on the advice of Canadian paleontologists and reflects importance, location in Canada, and visual suitability for depiction on stamps. A key element in the design is the rendition of the texture of the creature's surface, which is produced by a mezzotint stipple effect. Although the colour of these beasts is subject to speculation, each is shown of a hue appropriate to its surroundings.