Birds may have a reputation for being birdbrained - but it was superior brainpower that enabled them to survive when 85 per cent of animals around them were being wiped out, researchers have found.

Dinosaurs and ancient flying creatures including pterosaurs died out during the Cretaceous-Tertiary mass extinction 65 million years ago but modern birds survived and thrived.

Analysis of fossil skulls using computer tomography (CT) scans has now revealed that modern birds were able to adapt to the new conditions because their brains were so well developed.

It was the ability of birds to work out the solutions to problems, just as blue tits today learn to reach a creamy treat by pecking foil caps off milk bottles, that gave them the crucial edge. Others, such as members of the crow family, have even managed to learn to use tools.

“Birdbrained is a dreadful misnomer," said Dr Angela Milner, of the Natural History Museum in London. "It’s really quite an insult to birds when you think how sophisticated a lot of modern birds are.

“They can learn to talk, they can migrate over long distances, they have all sorts of capabilities and it all has to be crammed into a brain light enough that it doesn’t stop them flying. They were in some ways more advanced than dinosaurs.”

She and Dr Stig Walsh, a colleague at the museum, carried out scans that revealed the shape and volume of birds' brains gave them the mental agility they needed to adapt to difficult conditions whereas their competitors, the pterosaurs and earlier types of bird, were too dumb to cope with the changing world.

A key feature, researchers suggested, may have been the development in the brains of a structure called the wulst which is linked to visual perception.

In modern types of birds alive after the mass extinction it was small and had probably only recently evolved. In birds alive today it is much bigger, especially in species such as owls which rely heavily on eyesight, but the wulst was absent in pterosaurs and earlier forms of birds.

The birds seen around the world today are the direct descendants of the avian species that survived the mass extinction - thought to have been caused at least in part by a meteor strike which is estimated to have wiped out 85 per cent of animal species.

Dr Walsh said: “Our research suggests that the evolution of an expanded and structurally complex brain in the ancestors of living birds may have provided them with a competitive advantage over the more archaic bird lineages and pterosaurs.

“There were other flying animals around, such as pterosaurs and older groups of birds, but we’ve not really known why the ancestors of the birds we see today survived the extinction event and the others did not. It has been a great puzzle for us – until now.”

The researchers compared the brain cavity of Archaeopteryx, the earliest known type of bird which dates to 147 million years ago, with those of two marine birds which were alive after the mass extinction.

The modern-type marine birds, Odontopteryx toliapica and Prophaethon shrubsolei, dated from 55 million years ago and were closely related to today’s pelicans, frigatebirds, albatrosses and storm petrels.

Species that lived 10 million years after the mass extinction had to be used in the study because fossil bird skulls intact enough to be analysed in three dimensions are extremely rare. However, the brains of the two marine species were too well developed for key features, such as their ability to learn, to have evolved only after the mass extinction.

In a paper published in the Zoological Journal of the Linnean Society the researchers concluded that modern-style birds around when dinosaurs walked the earth had brains just as advanced in controlling sight, flight and the ability to learn as those of birds alive today.

Dr Walsh added: “In the aftermath of the extinction event, life must have been especially challenging. Birds that were not able to adapt to rapidly changing environments and food availability did not survive, whereas the flexible behaviour of the large-brained individuals would have allowed them to think their way around the problem.”

Scans revealed the creatures' brain power because the shape of the brain is imprinted in the inside of the skull so shows the shape and volume."

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