Analysis of the skulls of feathered but flightless dinosaurs shows they
developed bigger brains that may have paved the way for them to take to the
air.
Scientists have found that the reptiles' brains were much more like that of Archaeopteryx,
which is thought to be the first bird and lived 150 million years ago, than
had been previously thought.
It means these other flightless dinosaurs may have already taken key
evolutionary leaps towards becoming modern birds by developing "flight
ready brains".
Despite the term "bird brain" being commonly used as slang for
stupidity, birds actually have unusually large brains compared to their body
size.
This is most apparent in the forebrain, which provides the superior vision and
co-ordination necessary for flight.
The same characteristics, seen in Archaeopteryx, have now been found in
a number of flightless two-legged dinosaurs, thought to be distant relatives
of modern birds.
The enlarged bird-like brain can now be added to the other features they
possessed which makes them strong candidates as the ancestors of modern
birds, such as feathers and wishbones.
Scientists used CT scanners similar to those found in hospitals to peer inside
the brain cases of modern birds, Archaeopteryx, and several non-avian
dinosaurs.
The 3D X-ray images allowed them to reconstruct the skulls' interiors,
revealing brain volume and key areas where parts of the brain would have
been enlarged.
These included areas required for smell, vision and the cerebellum, which is
important for the coordination of movement and balance that would have been
required for flight.
"Archaeopteryx has always been set up as a uniquely transitional
species between feathered dinosaurs and modern birds, a halfway point,"
said lead scientist Dr Amy Balanoff, from the American Museum of Natural
History in New York.
"But by studying the cranial volume of closely related dinosaurs, we
learned that Archaeopteryx might not have been so special."
Like Archaeopteryx, the dinosaurs had large brains in relation to their
bodies.
Some, including the bird-like oviraptorosaurs and troodontids, actually had
brains that were even more enlarged than that of their flying cousin.
The dinosaurs appeared to have much of the flight controller wiring seen in
birds, even though they could not fly, the scientists reported in the
journal Nature.
more : http://www.telegraph.co.uk/science/dinosaurs/10214865/Dinosaurs-developed-bird-brains-before-they-could-fly.html
