Chinese and US scientists have teamed up to achieve breakthrough findings that dispel myths and explain how today's avian species came to be, Yang Feiyue reports.

Earth is home to about 11,000 bird species, accounting for the greatest diversity among terrestrial vertebrates. Yet question marks have long loomed over their origins and evolution. How closely are they related to dinosaurs? How did climate change influence their evolution? And how did they diversify biologically over time? Significant recent breakthroughs are helping answer these questions, thanks to genomic research on terrestrial vertebrates led by Chinese scientists, who collaborated with their US counterparts to make strides in unraveling the mysteries surrounding the origins of modern birds.

"Using new approaches to mine genomic information among 124 species, covering most modern birds' diversity, we found that the main lineages first divided into two groups — one mostly land-based and the other containing waterbird species," says Wu Shaoyuan, a professor from Jiangsu Normal University in Xuzhou, who led the research team.

The waterbirds were found during the study to be of a new evolutionary lineage, named Aquaterraves, which include seabirds and their close relatives.

Aquaterraves, along with the previously identified land birds (Telluraves), constitute the two major lineages of Neoaves, a clade to which almost 95 percent of the roughly 10,000 known species of extant birds belong.

After four years of efforts, the team has also shown that modern birds date back further than previously assumed — much earlier than the dinosaurian extinction event, which seems to have had a limited impact on their evolution.

Instead, a global warming event around 55 million years ago appears to have triggered the diversification that produced today's seabirds.