Study Finds Aquatic Roots for Today’s Birds

Five 110-million-year-old fossils found in northwestern China suggest that the lineage that gave rise to modern birds lived in the water, according to a new study.

The report, released Thursday by the journal Science, describes the fossils of an ancient bird called Gansus yumenensis.

The fossils indicate that Gansus, which was about the size of a pigeon, had bony knees and webbed feet for swimming, and the upper body structure of a strong flier. Their features are similar to those of ducks and loons. The fossils fill in a gap in the transition from primitive to modern bird species.

While there are older bird fossils, they belong to animals that eventually died out. Gansus is the oldest ancestor ever found in the line that led to modern birds, according to the researchers.

Gansus was first discovered in 1981 near the town of Changma in Gansu province. At that time, researchers only found the fossil of a partial hind leg and could not determine the species’ place in the evolutionary tree of birds.

The latest find was made by a research team led by Hai-lu You of the Chinese Academy of Geological Sciences in Beijing.

Focusing on an ancient lake bed, the team peeled back layers of rock before recovering the well-preserved bones. The lake environment had deposited sediment so gently that carbonized remains of feathers and the webbing from the birds’ feet were also found.

The preservation of the fossils allowed the researchers to determine that Gansus was an aquatic bird. “The webbed feet are the kicker,” said coauthor Matthew Lamanna of the Carnegie Museum of Natural History in Pittsburgh.

The one thing the team did not recover was an intact skull, but it has found fossils of plants, insects, fish and salamanders at the Changma site.

These finds will “help us to understand the ecological context and significance of the bird fossils,” Lamanna said.