A BIG gap in avian evolution may have been filled 鈥� or so a little bird tells us. With webbed feet and a lifestyle similar to a modern grebe or loon, this little bird is a 110-million-year-old fossil from Gansu province in China, and it hints that modern birds may have had aquatic ancestors.
Not much is known about the evolution of modern birds because fossils from this period are rare. Gansus yumenensis (pictured above) is the oldest known member of the group Ornithurae, which includes both modern birds and toothed marine birds that lived about 85 million years ago.
Until now, the only specimen of Gansus was a partly preserved leg discovered in the 1980s, and the species was thought to have had a wading lifestyle. When Hai-lu You of the Institute of Geology at the Chinese Academy of Geological Sciences in Beijing and colleagues returned to the site where the species was discovered, they found more than 40 well-preserved but headless fossils, including several near-complete skeletons of Gansus about 25 centimetres long, and clearly visible feathers. The new fossils show webbed feet, and muscle attachments indicate it lived on water 鈥� although the researchers say it was smaller than today鈥檚 divers, loons or grebes and probably a weaker swimmer (Science, vol 312, p 1640).
Advertisement
While Gansus is not a direct ancestor of the birds we see today, it is the closest species yet found from this period, says Jerry Harris of Dixie State College of Utah in St George, one of the team that made the discovery. 鈥淵ou wouldn鈥檛 have expected something to be so modern so far back into the Cretaceous,鈥� he says.
Other palaeontologists are cautious about the significance of the find. 鈥淚鈥檓 excited to see the material,鈥� says Julia Clarke of North Carolina State University. But she warns that it would be unwise to jump to conclusions about a link with modern birds until more fossils are discovered from this period. Gansus is three or four evolutionary steps away from living birds, she says.
Harris says the rocks where the discovery was made could yield many more new bird fossils. So far the team has only studied an area of about 10 square metres.
