First, the inner ear of tetrapods, including humans, contains structures called the cochlea and the basilar membrane. These structures are responsible for detecting and transmitting sound vibrations to the brain. However, in early tetrapods, these structures were relatively simple compared to those found in modern amphibians, reptiles, birds, and mammals. This suggests that their hearing ability was likely more limited.
Second, the auditory nerve, which carries signals from the inner ear to the brain, was also less developed in early tetrapods. This further supports the idea that their hearing was not as acute as in modern tetrapods.
Finally, the habitat of early tetrapods also provides clues about their hearing ability. They are believed to have lived in shallow water or swampy areas, where sound waves would have been muffled by vegetation and mud. This would have further reduced the effectiveness of their hearing.
Overall, while it is impossible to say for certain whether our tetrapod ancestors were completely deaf, the evidence suggests that their hearing was likely limited compared to modern tetrapods.
