Dinosaur family tree shows how birds evolved

Birds experienced an "evolutionary explosion" once a fully functioning bird body shape was complete in their ancestors - the gigantic dinosaurs, says a study.

Familiar anatomical features of birds - such as feathers, wings and wishbones - all first evolved piecemeal in their dinosaur ancestors over tens of millions of years, showed a family tree of meat-eating dinosaurs that the researchers created.

However, once a fully functioning bird body shape was complete, an evolutionary explosion began, causing a rapid increase in the rate at which birds evolved.

"This led eventually to the thousands of avian species that we know today," the study added.

For the study, the researchers examined the evolutionary links between ancient birds and their closest dinosaur relatives.

"There was no moment in time when a dinosaur became a bird, and there is no single missing link between them," said lead researcher Steve Brusatte from University of Edinburgh in Britain.

"What we think of as the classic bird skeleton was pieced together gradually over tens of millions of years," Brusatte added.

"Once it came together, it unlocked great evolutionary potential that allowed birds to evolve at a super-charged rate," Brusatte explained.

The researchers analysed the anatomical make-up of more than 850 body features in 150 extinct dinosaur species, and used statistical techniques to analyze their findings and assemble a detailed family tree.

"It is particularly cool that it is evidence from the fossil record that shows how an oddball offshoot of the dinosaurs paved the way for the spectacular variety of bird species we see today," Graeme Lloyd from University of Oxford noted.

The study appeared in the journal Current Biology.