Chinese paleontologists played a big role in fine-tuning the genetic estimates by examining the ages of 19 fossils.

"They have helped to convert the mutation rates seen in the genomes into specific times through fossil analyses," Wu explains.

If a branch appeared to be newer than a fossil that belonged to it, they would adjust the computer model that estimated the evolutionary pace.

Ultimately, biological data from the past was acquired and compared with data from modern times to trace the origin of birds, which Wu says will offer valuable information for humanity.

"The Earth has experienced major climate and environmental changes, which have affected biodiversity, and the data will offer us an insight and thus better prepare us for the future," Wu says. "As we are experiencing global warming, we need international cooperation to address the issue."

The study also revealed that living birds share a common ancestor that lived 130 million years ago. New branches of its family tree split off throughout the Cretaceous and afterward at a fairly steady pace, which Wu says was a result of the growing diversity of flowering plants and insects during the period.

These new discoveries have prompted scientists to reexamine bird evolution and pose a bold question about Earth's biological history: How exactly did birds embark on their evolutionary journey during the dinosaur era?

Experts believe the discoveries support Charles Darwin's classic theory of gradual species evolution and provide new evidence for the impact of global climate change on the unfolding of biodiversity.

"This research has led us to a new understanding of the timeline of bird evolution," says Zhou from the Institute of Vertebrate Paleontology and Paleoanthropology.

In contrast to the previously widely accepted model of rapid evolution, the evolution of modern birds appears to lean toward a slower and more continuous process, gradually changing through natural selection and showing synchronous trends with the evolutionary radiations of angiosperms, mammals, fish and insects, Zhou explains.

"This major discovery has inspired us to contemplate the evolution of life and Earth's history," he says.

"It not only deepens our understanding of the evolutionary history of birds and life on Earth but also enlightens us as to new considerations regarding the relationship between global climate change and the evolution of biodiversity," Zhou adds.

Wu says the new discoveries mark a first step in future studies.

"We will continue to collect and compare biological, climate and environmental data to develop a bigger picture and thus provide guidance and insight into the impact on biodiversity, and how to address challenges."

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