Plate tectonics: or, finding a home

They call it a theory but it’s no theory, I assure you. One day – one millennium, a million years – Laurasia cracked like an eggshell. Ocean waters rushed into the new channel, so narrow at first you could walk across it. The two landmasses remained locked in a hug for what seemed like eternity, and pterosaurs continued to migrate across the fault, as was their custom since the beginning. But over time, the chasm widened until the abyss was so enormous that many would die during the grueling, weeks-long flight. Finally, they had to choose: homecoming was to be settled on one shore or the other. Those that tried to straddle both worlds perished in the deep blue sea.