Two well-preserved fossils collected from deposits in China push back the evolutionary record of modern birds by five to six million years, reports a study in Nature Communications. The specimens, named Archaeornithura meemannae, are the oldest known records of Ornithuromorpha, the same evolutionary branch that gave rise to all bird species currently living.
Fossilised bird specimens from the Mesozoic era (252-66 million-years-ago) are rare, with little being known about the early evolutionary history of the ancestors of modern birds. Ornithuromorpha are thought to have represented around half the total diversity of bird species during the Mesozoic era. Other clades representing bird species during this time include the Enantiornithes, characterised by teeth and clawed wings. However, this group of birds are not thought to have left any living descendants, going extinct at the Cretaceous-Paleogene boundary approximately 66 million-years-ago.
Min Wang and colleagues describe this new species, unearthed from the Sichakou basin in Hebei, northeastern China, as having a near-completely preserved plumage with anatomical features characteristic of an aerodynamic lifestyle and manoeuvrability during flight. The absence of feathers on the upper leg, or tibiotarsus, is also indicative of a wading lifestyle, consistent with other fossil bird species found in similar deposits. Stratigraphic and radiometric dating of the geological layers from which these fossils were extracted indicates these new specimens lived during the Early Cretaceous period 130.7 million years ago, predating the last known specimens of this branch from the Lower Cretaceous, 125 million years ago.