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‘Bird brains’ evolved before birds: study

By Agence France-Presse
Wednesday, July 31, 2013 16:58 EDT
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A handout photo shows the fossil of Xiaotingia Zhengi, a previously unknown species of bird-like dinosaur from the Late Jurassic of China (AFP)
 
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New evidence has emerged that puts a dent into the reputation of the famous “first bird” — Archaeopteryx, a feathered descendant of the dinosaurs, which lived around 150 million years ago.

Three-dimensional scans of skulls of early birds and dinosaurs suggests that at least a few species of dinos that were contemporaries of Archaeopteryx had brains with the likely neurological wiring for flight, according to a paper published on Wednesday.

“Archaeopteryx has always been set up as a uniquely transitional species between feathered dinosaurs and modern birds, a halfway point,” said Amy Balanoff of the American Museum of Natural History.

“But by studying the cranial volume of closely-related dinosaurs, we learned that Archaeopteryx might not have been so special.”

Writing in the journal Nature, Balanoff’s team used computed tomographic (CT) scans to get a high-resolution image of brain size and regions in a dozen existing and extinct species.

Compared to reptiles, birds have large brains in relation to their body size — a phenomenon called “hyperinflation” which provides them with the superior vision and coordination needed to flight.

But the comparison turned up some bad news for Archaeopteryx.

Several other non-avian dinos that were sampled, including the feathery oviraptosaur and bird-like troodontid, had in fact larger brains relative to body size than Archaeopteryx did.

“If Archaeopteryx had a flight-ready brain, which is almost certainly the case given its morphology, then so did at least some other non-avian dinosaurs,” said Balanoff.

The finding adds to evidence that the gene pool that led to the first birds was far wider than thought.

Just a few years ago, biologists had a list of supposedly exclusive characteristics for birds, such as feathers and wishbones.

But these have been found to exist among non-avian dinosaurs, and now hyperinflated brains can be added to the list.

Agence France-Presse
Agence France-Presse
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