Dinosaurs developed bird brains before they could fly August 1, 2013Posted by Aries Munandi in General.
Tags: Archaeopteryx, bird brains, birds, Dinosaurs, Nature
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.
“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,” Dr Balanoff added.
The findings suggest that if Archaeopteryx was capable of flight, as some palaeontologists believe, then other feathered dinosaurs may also have been too.
However, these big-brained dinosaurs appeared to lack a key neural structure that may be an important flying aid in modern birds.
An indentation in the digital brain cast of Archaeopteryx is thought to be evidence of the wulst – German for “bulge” – which is used in information processing and motor control.
This was absent in the brain casts of flightless dinosaurs.