PuntaColorada:
Haha...I'm just now reading the first Mars (Barsoom) novel by Edgar Rice Burroughs, A Princess of Mars (1917) (A novel of the compiled serialization of stories written in 1912).
Earthman John Carter has met a lot of strange people and beasts, but so far no Corgis. Of course, I'm only about half-way finished! I'm on the lookout for a Corgi now!
There is a "Calot: A large dog-like creature with a frog-like mouth and three rows of teeth and ten legs. John Carter has his own calot, named Woola, who is his faithful companion." (Wikipedia) Maybe the Corgi evolves from this? I've never read any of Burroughs' books before (he of Tarzan fame), but I'm finding this one well worth the time to read.