3D X-ray scanners used to chart the evolution of avian flight

SCIENTISTS are charting the evolution of avian flight by digitally reconstructing extinct birds’ brains.

The researchers are using 3D X-ray scanning equipment to analyse whole skulls and fossilised fragments, and recreate accurate 3D models of avian brains.

They hope the research could help them discover more about when birds first evolved the power of flight.

Bird skulls grow to a fixed size before the creatures leave the nest, with the brain then growing to almost completely fill the cavity space. This means bird skulls can be used accurately to calculate the size and shape of the brain. By working this out, the size of part of the brain called the flocculus can be established.

The flocculus integrates visual and balance signals during flight, allowing birds to focus on objects moving in three dimensions while they are flying.

Dr Stig Walsh, project leader and Senior Curator of Vertebrate Palaeobiology at National Museums Scotland, said: “By charting the relative size of parts of the avian brain we believe we can discover how the flocculus has evolved to deal with different flying abilities, giving us new information about when birds first evolved the power of flight.”

Central to the research is the question of whether a larger flocculus is directly linked to a greater ability to process the visual and balance signals during flight.

If proven, this could mark a major step forward in understanding bird evolution.

The research is a collaborative project between National Museums Scotland, the University of Abertay Dundee, and University of Lethbridge, Canada.

Dr Walsh said: “This research has only been recently made possible through advances in X-ray micro-CT scanning. Unlike medical scanners, which take a series of slice images through an object that may be up to 1.5 millimetres apart, the 3D scanner at Abertay University can be accurate up to six microns.

“By using such powerful equipment and around 100 different modern species we’re beginning to understand much more about the evolution of flight.”

The computer analysis digitally reconstructs the shape and size of the skull, and creates a 3D ‘virtual’ brain model from the cavity inside the skull that housed the brain in life.

The project is also looking at some of the rarest fossils in the world — including the only two skulls of a flightless sea bird from the Cretaceous Period around 100 million years ago. What makes the fossils so rare is they were preserved in three dimensions in soft clay, not flattened by the pressure of earth above them like most bird fossils.

Patsy Dello Sterpaio, joint project researcher at Abertay University, said: “This is a hugely exciting project, which benefits greatly from Abertay’s high-powered micro-CT scanner. We hope that this joint project can produce not only incredible images, but also help answer some of these important unresolved questions about the evolution of flight.”

The project is also looking at flightless birds such as the dodo, to see whether the flocculus has become smaller with loss of flight.