The diversification of modern birds was mostly dictated by climate change and plate tectonics, new research shows. File photo by UPI/Debbie Hill | License Photo
WASHINGTON, Dec. 14 (UPI) -- New physiological and genetic analysis suggests all modern birds are descended from a single species in South America.
The research also shows diversification was largely dictated by climatic changes, particularly widespread cooling trends beginning 91 million years ago.
Previously, researchers thought the disappearance of the dinosaurs 66 million years ago was the chief driver of diversification -- the branching off of new bird species. But the latest findings, published last week in the journal Scientific Advances, contradict this theory.
"Our results show that rapid diversification began before the mass extinction event and coinciding with a long-term cooling trend at the end of the Cretaceous," Santiago Claramunt, an ornithologist with the American Museum of Natural History, told Discovery News.
Though birds surely benefited from ecological niches left empty by the dino's downfall, the evidence suggests branches from the family tree of modern birds began radiating prior to the extinction event.
As cooling fragmented tropical environs, newly evolved bird species set out to colonize new territory, utilizing land bridges to move from South America onto other continents.
Researchers analyzed genetic data from 130 fossils representing all major bird families in order to build an evolutionary time tree, allowing scientists to pinpoint when and where modern bird lineages first emerged.
Though the evidence points to a single founding father in South America -- a species that lived alongside the dinosaurs 95 million years ago -- scientists haven't been able to determine the identity of the mystery bird.
"It's a difficult problem to solve because we have very large gaps in the fossil record," explained Joel Cracraft, curator of the museum's ornithology department. "This is the first quantitative analysis estimating where birds might have arisen, based on the best phylogenetic hypothesis that we have today."