The cliffs grew taller and steeper as the valleys between tepuis deepened.

What had once been a continuous highland ecosystem became an archipelago of sky islands, each with its own population of organisms descended from those that had been present before the isolation became complete.

This model — progressive isolation through erosion of the surrounding landscape — is consistent with both the geological history of the tepui region and the biological observation that tepui summit species are most closely related to species from surrounding lowland and highland habitats rather than to species from distant geographic regions.

For organisms that colonized the summits after the isolation became complete — those that arrived after the cliffs had grown to their current impressive heights — the routes of colonization are more varied.