Conan Doyle drew on accounts of the real tepui mountains — including im Thurn’s published account of the 1884 Roraima ascent — for the geographical inspiration of his novel.

The description of the cliff-walled plateau, the strange vegetation, the isolation from the surrounding lowland world, the sense of a landscape operating under different rules — all of these elements came from the real tepui landscape.

But the creatures that Conan Doyle imagined inhabiting his fictional plateau were pure invention, and the specific claim that dinosaurs or other Mesozoic animals might survive on tepui summits has no scientific support whatsoever.

The non-avian dinosaurs went extinct approximately 66 million years ago, at the end of the Cretaceous period, in one of Earth’s major mass extinction events.