The extinction of the dinosaurs touched off an evolutionary "big bang" that lasted 15 million years or less and led to so many types of birds we see today, according to the findings from a megaproject involving hundreds of researchers from 20 countries.
Over the course of more than 4 years, the Avian Phylogenomics Consortium sequenced the genomes of 48 species representing every major limb of the bird world's evolutionary family tree, which takes in more than 10,000 species around the world.
Those genomes were compared using the equivalent of 400 years of supercomputer time, and organized using a new statistical method for tracing genetic connections.
The results appear in a special edition of Science on 12th December (with simultaneous publications of related articles in other high profile journals).
Associate Professor Ho, from the University's School of Biological Sciences, is an author on a Science paper and two articles in GigaScience. He contributed his expertise in using a technique known as 'molecular clock' analysis to estimate birds' evolutionary timescales, using genome data and fossil evidence.
Ho's research assisted in confirming that some of the first lineages of modern birds appeared about 100 million years ago but that almost all of the modern groups of birds diversified in a small window of less than 10 million years, just after the dinosaurs were completely eliminated by an asteroid.
So while cormorants and grebes are both waterbirds with webbed feet that dive to catch their prey they are, despite these similarities, from completely distinct lineages, Ho said.
Another important finding is that the ancestor of most of the land birds we see today is probably an apex predator that gave rise to eagles, raptors, falcons and owls in quick succession before leading to land birds such as woodpeckers and songbirds.
Ho further added that with the demise of the dinosaurs, mammals and birds became more diverse and occupied all of the niches that had previously been dominated by dinosaurs.