U.S.A., 1930's

Xerox Sinclair meter franking
Tony Johansen Sinclair meter franking
From the nineteen thirties until the fifties, the Sinclair Oil Company used a number of different meter frankings with a sauropod to advertise their motor oil. They chose a dinosaur as company logo as a symbol of the great length of time their oil spent in the ground.
These highly sought after items are the very first occurrence of a dinosaur in philately.
Note the different words, 'Opaline motor oil' and 'Pennsylvania motor oil'.