The most comprehensive family tree of meat-eating dinosaurs ever created reveals key details of how birds evolved from them.
University experts have shown that birds’ familiar anatomical features - such as feathers and wings - all first evolved in their dinosaur ancestors over tens of millions of years.
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.
A team of researchers examined the evolutionary links between ancient birds and their closest dinosaur relatives.
They analysed the anatomical make-up of more than 850 body features in 150 extinct species, and used statistical techniques to assemble a detailed family tree.
Our study adds to a growing number of works that approach this problem from different angles, but all seem to confirm that the origin of birds was a truly special event in Earth history. 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.
Based on fossil records, researchers say the emergence of birds 150 million years ago was a gradual process, as some dinosaurs became ever-more bird-like over time.
This makes it very difficult to draw a dividing line on the family tree between dinosaurs and birds.
There was no moment in time when a dinosaur became a bird, and there is no single missing link between them. What we think of as the classic bird skeleton was pieced together gradually over tens of millions of years. Once it came together fully, it unlocked great evolutionary potential that allowed birds to evolve at a super-charged rate.
Findings from the study support a controversial theory proposed in the 1940s that the emergence of new body shapes in groups of species could result in a surge in their evolution.
The study is published in the journal Current Biology.