The ancestors of birds were dinosaurs.

Maniraptorans were meat-eating dinosaurs. These theropod creatures became birds about 150 million years back. Recent findings at the McGill University, as reported on the Science Daily, show that several maniraptorans were similar to birds. They had hollow bones, feathers, high metabolism and small-sized bodies.

Hans Larsson and Alexander Dececchi of the McGill University examined fossil data to find out when exactly the forelimbs of those dinosaurs evolve into flying instruments called wings. Their study was published on Evolution (September issue). Dececchi and Larsson come to know that the scaling in limb lengths in comparison to the body size was quite stable throughout the history of carnivorous dinosaurs.

Mr Larsson, who is Canada Research Chair in Macroevolution at McGill's Redpath Museum, said that birds experienced a sudden change in the development mechanisms. Their hind limbs and forelimbs became conditional on diverse length controls, he said. Mr Dececchi, who is a postdoctoral researcher at the University of South Dakota, said that the origin of powered flight and birds is a major transition in evolution. He said that their findings advocate that the general body size and the limb lengths in birds must have been dissociated before their radiation became successful.

There were previous findings which suggested that the birds had not been originated from tree dwellers. Those findings, along with the present ones, have been instrumental in illuminating the ecology of bird antecedents, Mr Dececchi said. it is crucial to know where the birds originated from and how they reached where they belong to at the moment. These understandings are critical to know how the present world travelled its way so far.

The Fonds de recherche du Québec - Nature et technologies, the National Sciences and Engineering Research Council of Canada and the Canada Research Chairs programme funded the significant research done by Hans Larsson and Alexander Dececchi.