The prolific and imaginative Edgar Rice Burroughs not only wrote the Tarzan series and the John Carter of Mars series, but a series about "Pellucidar," a great cavernous world inside the earth, populated by humans, but also by all kinds of strange critters and monsters (not all dinosaurs died in the meteor strike 60,000,000 years ago--some moved "indoors" and continued to evolve). Great stuff! Burroughs doing his thing.

But it kinda makes you wonder sometimes. . . .

Don Firth