Scientists say the mapping of the genomes of 48 birds -- one species from every major lineage of birds -- has yielded new understanding of their evolutionary links back to dinosaur ancestors.

The Avian Phylogenomics Project has spent 4 years sequencing genomes of species taken from virtually every major branch of the evolutionary family tree of today's birds, researchers say.

The result has the publication of more than two-dozen scientific papers in a number of journals.

It has long been known that after birds survived the mass extinction that removed dinosaurs from the face of the Earth they underwent a rapid explosion of evolution, but exactly how they arrived at the spectacular biodiversity of modern bird species numbering in excess of 10,000 has been a mystery to science.

Modern birds divided into species early and in quick succession, so they haven't evolved sufficient distinct genetic differences at the genome level to allow a determination of their earliest branching order, the researchers said.

To resolve that timing and investigate the relationships of modern birds species, an international research consortium set out to sequence, assemble and compare the complete genomes of 48 modern representative bird species.

The project involved some 200 researchers in laboratories in 20 countries and several months of crunching the gathered data using a supercomputer.

"This is the largest whole genomic study across a single vertebrate class to date," says consortium leader Guojie Zhang of the National Genebank at BGI in China.

The genomic effort has yielded new insights into birds' evolutionary origins, how their genetic makeup drives their behavior, and how various bird species are linked and related to each other, the researchers report.

Before the Avian Phylogenomics Project began the genomes of only a few bird species such as turkeys, chickens and zebra finches had been deciphered, and researchers knew very little about the underlying genetic connections between bird species.

"In the past, people have been using one, two -- up to 10 or 20 genes -- to try to infer species relationships over the last 100 million years or so," says Duke University neuroscientist Erich Jarvis, one of the project's leaders. "Our theory has been, if you take the whole genome, you would have a more accurate species tree than just one or two genes alone."

The process of creating the evolutionary tree for birds from genome sequencing could also be used to take a fresh look at other branches of the overall tree of life, said Tandy Warnow, a University of Illinois bioengineering and computer science professor who was the leader of the project's computational work.