Hearing, which initially appeared in early fish, underwent a remarkable transformation as vertebrates transitioned to terrestrial life a bit after 400 million years ago. Early forms of hearing involved simple pressure-sensitive cells that could detect vibrations in water. As amphibians moved onto land, rudimentary hearing evolved into processing airborne sound. This transition further drove the need for enhanced brain capacity to process increasingly complex sensory information.

Acanthostega (circa 365 Mya): Hearing, a critical evolutionary advancement, underwent significant changes as vertebrates transitioned from aquatic to terrestrial environments. While the earliest forms of hearing evolved in water, allowing organisms to detect vibrations through their bodies, the move onto land posed new challenges and opportunities for auditory systems. Acanthostega, an early amphibian, exemplifies this transition. This period marks a crucial phase in the development of auditory systems capable of detecting a broader range of sounds, setting the stage for the complex hearing abilities observed in later terrestrial vertebrates.