Science Literature

"Several years ago, paleontologist Jennifer Clack of the University of Cambridge in the U.K. proposed that hearing evolved [in the Mesozoic] to help vertebrates catch the buzzing insects that were undergoing an evolutionary explosion around the same time." However, a report has now been published demonstrating the presence of true tympanic ears in reptiles from the Permian Period, reputed to be 60 million years earlier, when "buzzing insects were not as prevalent". "The researchers were able to identify six apparently closely related species, all of which showed clear evidence of large, eardrumlike structures covering much of their cheeks. In the better preserved specimens, inner ear bones similar to those of modern ears were found, including a stapes."
The researchers "examined the functional performance of this unique and unexpected auditory arrangement, and discovered that these little reptiles were able to hear at least as well as a modern lizard." New data like this is a stimulus to new hypotheses and the authors have suggested "that the auditory sense might have arisen among vertebrates that lived in dimly lit niches."
Rather than discuss the Darwinian tendency to explain origins via selection for functionality (hearing buzzing insects enhances survival/hearing allows hunting in the night and enhances survival), I want to draw attention to the early appearance of all the important complex organs: "By the end of the Paleozoic many of the major adaptive features characterizing amniote evolution had evolved; important examples include the ability for flight, secondary aquatic lifestyle, and high-fiber herbivory. The discovery of a highly-evolved auditory apparatus in Middle Permian parareptiles even further emphasizes that the entire groundplan for the impressive evolutionary history of amniotes was already largely in place by the end of the Paleozoic; what followed was in fact only a subsequent tinkering of earlier inventions." Darwinism needs time, but the fossil record no longer provides it. Complexity appears abruptly and most of the subsequent variations are adaptations. Welcome the day when evolutionary theorists appreciate that the origin of complexity and the "subsequent tinkering" are two distinct issues to address.

Impedance-Matching Hearing in Paleozoic Reptiles: Evidence of Advanced Sensory Perception at an Early Stage of Amniote Evolution
Johannes Muller, Linda A. Tsuji
PLoS ONE, 2007, 2(9): e889. doi:10.1371/journal.pone.0000889

Background: Insights into the onset of evolutionary novelties are key to the understanding of amniote origins and diversification. The possession of an impedance-matching tympanic middle ear is characteristic of all terrestrial vertebrates with a sophisticated hearing sense and an adaptively important feature of many modern terrestrial vertebrates. Whereas tympanic ears seem to have evolved multiple times within tetrapods, especially among crown-group members such as frogs, mammals, squamates, turtles, crocodiles, and birds, the presence of true tympanic ears has never been recorded in a Paleozoic amniote, suggesting they evolved fairly recently in amniote history.
Conclusions/Significance: Using modern amniotes as analogues, the possession of an impedance-matching middle ear in these parareptiles suggests unique ecological adaptations potentially related to living in dim-light environments. More importantly, our results demonstrate that already at an early stage of amniote diversification, and prior to the Permo-Triassic extinction event, the complexity of terrestrial vertebrate ecosystems had reached a level that proved advanced sensory perception to be of notable adaptive significance.

See also:

Balter, M., Let's Hear It for the First Ears, ScienceNOW Daily News, 12 September 2007.

Prehistoric Reptiles From Russia Possessed The First Modern Ears, Science Daily, September 12, 2007.