Earliest bird 'heard like an emu'

Archaeopteryx fossils have been known since the 1800s

The earliest known bird, the magpie-sized Archaeopteryx lithographica, was able to hear like a modern emu.

In this respect at least, Archaeopteryx appears to have been more bird-like than reptile-like.

A team of scientists found the length of a part of the inner ear of birds and reptiles could be used to predict their hearing ability.

Details of the work appear in one of the journals of the UK Royal Society.

The researchers tested whether the length of the cochlear duct (part of the cochlea - the organ of hearing in animals, which lies in the inner ear) could be used to infer hearing ability in a group of modern birds and reptiles.

These included the barn owl, emu, alligator and green turtle.

They found that animals with a long cochlear duct tended to have the best hearing and vocal ability.

Modern bird species are known to possess relatively longer cochlear ducts than living reptiles.

A long cochlear duct is also an indicator of an individual's complex vocal communication, living in groups and even habitat choice. This appears to be true for both mammals and birds.

Dr Paul Barrett, a palaeontologist at the Natural History Museum, commented: "In modern living reptiles and birds, we found that the length of the bony canal containing the sensory tissue of the inner ear is strongly related to their hearing ability.

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The scientists used 3D scans of birds - like the CT scan of this barn owl - to discover more about the ancient creature's hearing

"We were then able to use these results to predict how extinct birds and reptiles may have heard, and found that Archaeopteryx had an average hearing range of approximately 2,000 Hz.

"This means it had similar hearing to modern emus, which have some of the most limited hearing ranges of modern birds."

Previously, researchers have only been able to estimate how prehistoric animals heard sounds by examining the skulls of damaged fossils and relating the size of brain regions involved in hearing to hearing ability.

They did this using comparisons with a fossil's living counterpart.

However, the technique of modern computed tomography, or CT imaging, allowed Dr Barrett and his colleagues to accurately reconstruct the inner ear anatomy of various intact bird and reptile specimens.