New clues about ancient birds

Peter DodsonPhoto credit: Candace diCarlo

In 1984, the partial remains of a bird fossil from the age of dinosaurs were accidentally discovered in the Gansu province of northwestern China. The discovery was then largely forgotten by the scientific community.

Nearly 20 years later Hai-lu You, a Penn Ph.D. graduate, returned to his native China to revisit the site where the Gansu fossil emerged.
The following year he went back, with Matthew Lamanna of Carnegie Natural History Museum and a fellow Penn Ph.D. recipient, and Peter Dodson, professor of anatomy at the Vet School and professor in the Department of Earth and Environmental Sciences.

While Dodson (at right) usually goes to China to look for horned dinosaur fossils, what he and his former students found, instead, was, he says, “a serendipitous discovery.” The team uncovered five remarkable bird fossils of an early ancestor to modern-day warm-blooded birds. Gansus yumenensis, named for the Gansu province and the nearby city of Yumen, lived 105 to 115 million years ago in an aquatic environment. But while the ancient birds bear similarities to modern birds, Dodson cautions this doesn’t mean the creatures are just like loons or ducks. “They’re much more similar to what we call the base of the modern bird,” he says.
The team, which also includes Dodson’s former student Jerald Harris, now of Dixie State College, reported their findings in the journal Science and made international news with their discovery.

Though none of the fossil remains included intact skulls—which could provide a complete picture of what the animals ate—the team surmised the animals likely consumed fish, insects and plants. The skeletons revealed plenty of other key information, too: Its upper body structure suggests that Gansus could take flight from the water, and webbed feet and bony knees are clear signs that the bird could swim. “It tells us something about the pace of bird evolution,” says Dodson.

In fact, Gansus fills in the big gap between very early birds and those that came at the end of the Dinosaur Age: Gansus is the oldest example of near-modern birds that branched off from the ancient creature’s family tree. The fossil also provides a unique opportunity to study the microscopic structure of the bird bones. “A good study of bone structure will be very telling in understanding growth rate and metabolic rate and something about the metabolic history of birds,” Dodson says. “The work there is ongoing.”

Despite the international media attention the find has received, Dodson insists he’s no expert in this field (usually he studies horned dinosaur fossils). Through this discovery, he hopes to build a complete fauna picture of the Gansu province in China. They’ve already uncovered specimens of salamanders and frogs and Dodson wants to add more discoveries to the list. “I’d like to find dinosaurs, if possible,” he says.

Originally published on September 7, 2006.

Originally published on September 7, 2006