Not so bird-brained, then: Flightless dinosaurs had brains hardwired for flying long before they took to the air
- U.S. scientists are claiming that bird brains predate birds themselves
- Some flightless dinosaurs had the brain circuitry needed to fly, they found
- The study provides an insight into the factors that drive brain evolution
Bird brains developed in dinosaurs well before the creatures learned how to fly, a study has shown.
Evidence suggests that several flightless dinosaurs had evolved the kind of neural circuitry needed to take to the air.
Their brains were much more like that of the first bird, Archaeopteryx, than had been previously thought.
An artist's impression of Xiaotingia Zhengi, a previously unknown species of bird-like dinosaur from the Late Jurassic of China. Scientists now believe dinosaur brains were much more like that of the first bird than had been previously thought
A CT scan showing the brain structures of Zanabazar junior, a troodontid dinosaur. The endocast is partitioned into the following regions: brain stem (yellow), cerebellum (blue), optic lobes (red), cerebrum (green), and olfactory bulbs (orange). Several non-avian dinosaurs sampled were found to have larger brains relative to body size
Despite the term ‘bird brain’ being a byword for stupidity, birds have unusually large brains compared with the size of their bodies.
THE DINOSAUR THAT CHANGED THE WAY WE LOOK AT BIRDS
The discovery of a new feathered dinosaur earlier this year challenged widely-held views on the origin of flight.
In a groundbreaking study, experts revealed how the Eosinopteryx roamed the earth long before the bird-like beasts it was thought birds evolved from.
Scientists previously believed that birds evolved from dinosaurs called theropods from the Early Cretaceous period, about 120-130million years ago.
But recent discoveries in north-eastern China of much older feathered dinosaurs from the older Middle-Late Jurassic period have cast doubt on the old theory.
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.
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, not only revealing brain volume, but also key features such as the smell and vision centres and cerebellum.
A bird brain can now be added to the other bird-like features they possess, such as feathers and wishbones.
‘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.
The fossil of Xiaotingia Zhengi, a bird-like dinosaur. Evidence suggests that several flightless dinosaurs had evolved the kind of neural circuitry needed to take to the air, before developing the physical ability to do so
‘But by studying the cranial volume of closely related dinosaurs, we learned that Archaeopteryx might not have been so special.’
In addition to calculating the total volume of each digital brain cast, the research team also determined the size of each brain's major anatomical regions.
They found that as well as Archaeopteryx, several other non-avian dinosaurs sampled, including bird-like oviraptorosaurs and troodontids, had larger brains relative to body size.
Professor Gabriel Bever, of the New York Institute of Technology, said: ‘The story of brain size is more than its relationship to body size.
‘If we also consider how the different regions of the brain
changed relative to each other, we can gain insight into what factors drove
brain evolution as well as what developmental mechanisms facilitated those