High-powered, three-dimensional X-ray scanning equipment at a University in Scotland is being used with a University of Lethbridge researcher's large collection of bird brain specimens to help chart the evolution of flight in birds.
U of L neuroscientist, Dr. Andrew Iwaniuk, who has amassed the world's largest collection of bird brain sections, is partnering with researchers at the National Museums Scotland and the University of Abertay Dundee to digitally reconstruct the size of bird brains using ancient fossils and modern bird skulls.
"The majority of my research addresses how the brain evolves, particularly with respect to behaviour," says Iwaniuk. "For example, my NSERC funded research aims to determine how the evolution of novel courtship behaviours in birds is associated with changes in the brain. This research is critical to understanding how the brain evolves in all animals, including humans."
The opportunity to be part of both an evolutionary and behavioural program appeals to Iwaniuk.
"Dr. Stig Walsh (National Museums Scotland) contacted me about a potential collaboration on the evolution of avian brains," says Iwaniuk. "He was interested in reconstructing the brains of extinct birds and comparing the shape of their brains with that of modern birds. Similar comparisons have proven useful in understanding the behaviour of dinosaurs and various extinct mammals, including sabre-toothed cats and the ancestors of humans. However, there are few such comparisons involving birds. In this project, we aim to determine if there are changes occurring in the brain that coincide with the evolution of flightlessness."
Among other tools, researchers are using an incredibly sensitive CT (computerized tomography) scanner at Abertay University in Dundee, Scotland. They intend to analyze whole skulls and fossilized fragments to recreate accurate 3D models of extinct birds' brains. This is where Iwaniuk's collection comes into play.
He and Dr. Doug Wylie, a colleague at the University of Alberta, have hundreds of bird species catalogued, and have recorded and sectioned their brains to chart changes in development. The brain sections could be measured to micron accuracy to re-create the complete brain, and then be matched with a similar bird skull in modern and fossil form. Bird skulls grow to a fixed size before they leave the nest, with the brain then growing to almost completely fill the cavity space. This means that bird skulls can be used to accurately calculate the size and shape of the brain.
By working this out, the size of the flocculus, a small part of the cerebellum responsible for integrating visual and balance signals during flight, can be established. The flocculus allows birds to focus on objects moving in three dimensions while they are flying.
Walsh, project leader and senior curator of Vertebrate Palaeobiology at National Museums Scotland, says that by charting the relative size of parts of the avian brain, researchers believe they can discover how the flocculus has evolved to deal with different flying abilities.
"This gives us new information about when birds first evolved the power of flight," he says.
The central research question is 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, and may shed light on whether some remarkably bird-like dinosaurs were truly dinosaurs or actually secondary flightless birds.
"The inability to fly has evolved numerous times through the evolutionary history of birds," says Iwaniuk. "Examples include penguins, kiwis and ostriches, as well as the extinct Great Auk of Newfoundland and Labrador and the Dodo. In fact, many flightless species are highly endangered or extinct, which is why this study relies on museum specimens to chart the shape and size of the brain. By performing these comparisons, we hope to better understand the behaviour of several extinct species as well as the changes required in the brain to evolve flight."
The researchers believe that the brain power required for flight may have become reduced in such species.
The project is scheduled to run until early 2012.