The end of the Gorgon Era did not come from a meteor or a plague, but from a slow, agonizing shift in the planet's chemistry. The oxygen levels, raised by the very titans themselves through their terraforming respiration, began to favor smaller, faster, and more efficient organisms. The era of the "Monstrous Giants" was being suffocated by its own success. The air became too rich for their massive, slow-burning systems, causing their internal furnaces to burn out of control or their lungs to seize under the weight of an atmosphere that was now too dense. The very atmosphere they had helped create was now a poison to their ancient, sulfur-based biology, a cruel irony of evolution where the architects of the new world were the only ones who could not live within it.
The Gorgon-Walkers began to find the air too thin, the heat too diffused. They became sluggish, their massive frames unable to sustain themselves in the changing atmosphere. As they died, their bodies became the mountains and hills of the new world. Their calcified bones provided the mineral-rich soil that would eventually support the first true forests of the coming Cenozoic. Every valley was once a throat; every mountain range was once a spine. The world as we know it is built upon the literal corpses of the Gorgons, a landscape of hidden monsters waiting beneath the grass and the trees. Their blood, enriched with rare earths and iridium, seeped into the deep veins of the planet, creating the mineral deposits that future civilizations would eventually mine to build their own metal empires. We walk upon the petrified remains of a nightmare, unaware that the foundations of our cities are the ribs of titans.
In the shadows of their decaying corpses, a new kind of creature began to emerge. They were the Proto-Simians, the scuttling, fur-covered ancestors that would one day branch into the lineage of apes and humans. These small, agile mammals looked at the massive, fossilized skulls of the Gorgon-Walkers and felt a primal, ancestral fear that bypassed logic. They didn't know the names of the titans, but they felt their presence in the deep tremors of the earth and the strange lights of the aurora. They lived in the "Gills" of the dead giants—the massive ribcages and hollowed skulls—finding safety from the weather in the calcified remains of their betters. This collective trauma was etched into the Proto-Simian genome, manifesting as an instinctive dread of the deep earth and the high sky, a genetic memory of when the world was ruled by gods of fire and glass.
The Gorgon-Walkers did not go extinct in the traditional sense. They retreated into the deep places of the world—the hollow earth, the bottomless trenches, and the hearts of dormant volcanoes where the old conditions of the Cinder Epoch still persisted. They went into a long hibernation, their metabolism slowing to a near-halt, waiting for the cycle to turn. They waited for the air to thicken with smoke once more, for the planet to warm back to the temperatures they craved. They are the "Sleepers," watching from the darkness with sensory pits that have waited millions of years for a signal. They possess a patience that is geologic in scale, viewing the rise of the mammals and the eventual evolution of the apes as nothing more than a momentary flicker of light in the long dark of their rest.
The era of the Proto-Simians was about to begin, built upon the graves of the most terrible wonders the world had ever known. But these ancestors were mere tenants, unaware that their landlord was beginning to stir in response to the changing climate. As the forests grew over the bones of the Gorgons, the apes began to climb, moving further away from the heat of the earth and into the canopy. The monsters were never truly gone; they were simply waiting for the fire to return, for the world to once again become the bruised, ash-choked paradise of their birth. The story of the mammalian rise is but a brief, noisy interlude in the eternal, silent reign of the Gorgon, and as the ground begins to shake in ways no primitive mind can explain, it is clear that the dawn of the ape was merely the dusk of the titan.