Science Even the ancestors of today's reptiles could hear well
By analyzing ancient reptile fossils and modern reptile embryos, an international research team has concluded that the ancestors of today's reptiles already had eardrums for hearing. Perhaps this saved them from extinction.
16.10.2024, 05:09
SDA
Because those with good hearing were able to perceive insects as food and avoid predators, the team writes in the journal "Current Biology".
The study was carried out by researchers from Brazil, the USA and Germany under the leadership of Mario Bronzati from the Department of Geosciences at the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen. Descendants of the first reptiles today include more than 20,000 species of crocodiles, lizards, snakes and turtles.
Earliest eardrums present
For the study, the experts investigated the origin and development of eardrum hearing in modern reptiles and their numerous extinct relatives - by combining information from palaeontology and developmental biology. They also collected developmental data from lizard and crocodile embryos.
During the analysis, the researchers discovered remodeling in the bone structure of the ear region in the ancestors of today's reptiles. These changes led to the formation of an ear opening and an area for the attachment of the eardrum.
According to the research team, the evolutionary innovation arose after the first vertebrates mastered the transition from water to land around 400 to 360 million years ago. Since sound waves propagate differently in air and water, the animals were confronted with the problem of hearing. Although the first amphibian land vertebrates could already hear, the development of an eardrum improved the hearing of these animals immensely.
Relatives without eardrums died out
"This is the first study to document the origin of the eardrum in reptiles in detail. Our results suggest that the ancestor of all reptiles already had an eardrum, similar to what we find in today's species. We also show that the closest relatives of today's reptiles did not have eardrums," says Bronzati.
According to Bronzati and colleagues, these relatives all died out at the Permian-Triassic boundary around 250 million years ago. This suggests that the development of the eardrum could have been a key event in the evolutionary success of reptiles.
