What global environmental change led to the contraction of seas preferred by *Megalodon*?

Declining global ocean temperatures

The survival outcome for different shark lineages was significantly influenced by major shifts in global climate over millions of years. The environment that *Megalodon* favored consisted largely of vast, warm, shallow seas. As global ocean temperatures began to undergo a significant decline, these preferred habitats contracted severely. In contrast, the ancestors of the modern great white were evolving toward a body plan that was comparatively more robust and slightly more cold-tolerant. This positioning allowed them to successfully adapt and thrive in the cooler coastal upwelling zones that replaced the *Megalodon*'s optimal hunting grounds, highlighting environmental adaptability as the key engine for long-term survival.