The earliest evidence yet of modern ears in terrestrial vertebrates has been discovered in reptile fossils from central Russia, paleontologists say.
The animals may have been among the first nocturnal vertebrates, using their advanced hearing and large eyes to communicate with each other and hunt insect prey at night.
This would have given them a niche during a time when Earth was crowded with animals.
The reptiles lived 260 million years ago, during the Permian period, which lasted from 299 to 251 million years ago.
That's about 50 million years earlier than modern ears were thought to have developed in terrestrial vertebrates.
"The fact that they evolved a modern ear emphasizes that the ecosystems in the Permian period were advanced," said lead author Johannes Müller of Humboldt University in Berlin.
The ears were found in six fossils of different species of para-reptiles, small, lizardlike animals about 1.5 feet long (0.45 meter long). "Think of a chubby lizard with a wide head," Müller said.
All the reptiles had a true middle ear, which allowed them to hear a range of frequencies. (Related news: "Big Dinosaurs Heard Only Low-Pitch Sounds, Experts Suggest" [June 8, 2007].)
"It is the oldest evidence of advanced hearing in any land animal that lays a hard-shelled egg," he said.
One Big Eardrum
The ancient reptiles' advanced hearing apparatus was very similar to that of modern reptiles, Müller said.
"It's like a hole in the cheek region, covered with a thin sheet," he said.
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