A Chinese dinosaur hunter has teamed up with American paleontology professors to publish an article in the December issue of Science that makes a compelling case that birds descended from dinosaurs.

Xing Xu, a professor at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, worked closely with David Varricchio, an associate professor of paleontology at Montana State University in Bozeman, Montana.

They first met at a scientific conference in Japan last year. That eventually led to the paper An integrative approach to understanding bird origins. Xu is the lead author and in addition to Varricchio, other co-authors include Zhonghe Zhou of the Institute of Vertebrate Paleontology and Paleoanthropology and Cheng-Ming Chuong of the University of Southern California.

The science journal Nature profiled Xu in 2012, saying that he was revolutionizing ideas about dinosaur evolution and helping to make China into a paleontological powerhouse.

"He has been at the forefront of most Chinese dinosaur discoveries in the last 15 years or so," Varricchio told China Daily in an interview. "He is very well respected and very knowledgeable about dinosaurs and birds."

The paper in Science points to recent dinosaur fossil discoveries in China as providing more proof that birds descended from theropod dinosaurs.

Varricchio said there are some key elements that support the hypothesis birds came from dinosaurs. "Birds have an unusual respiratory system that involves air sacs which is similar to small dinosaurs," he said.

Another factor is that small carnivorous dinosaurs had eggs that were similar to birds. "There is research that shows small carnivorous dinosaurs would glide or jump from trees," said Varricchio.

The paper noted that recent discoveries of feathered dinosaur fossils from Jurassic and Cretaceous sediments showed a variety of feathers that demonstrated a trend toward increasing complexity.

Varricchio, who focuses on dinosaur reproduction, noted that many reproductive features associated with modern birds first evolved among carnivorous dinosaurs, particularly those close to the ancestry of birds.

So that begs the questions which species came first .-.the dinosaurs or the birds? "Recent research indicates carnivorous dinosaurs existed before the first bird," Verricchio said.

He said fossil discoveries in China's Liaoning Province in northeast China were invaluable to him and the other researchers on this paper. According to a report in National Geographic magazine, the province has become one of Earth's most celebrated fossil beds. The magazine said discoveries there are giving us a glimpse of life from 130 million to 110 million years ago.

The website of the American Museum of Natural History said: "The Liaoning fossils are also amazingly well-preserved. Delicate features like skin texture and feathers are clearly visible in many of the animal specimens. Indeed, the discovery of numerous feathered dinosaurs in Liaoning continues to reveal important information about the origin of feathers and flight, as well as the evolution of birds."

paulwelitzkin@chinadailyusa.com