‘Bird brains’ evolved before birds: study
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.