by Mary Caperton Morton Friday, August 21, 2015
Two specimens of the oldest- known ornithuromorph yet discovered, Archaeornithura meemannae, thought to have been a wading bird, were recently found in China. Credit: Zongda Zhang.
The discovery of two well-preserved fossils in the Sichakou Basin of northeastern China has pushed back the known evolutionary record of birds by as much as 6 million years, according to a new study published in Nature Communications.
The specimens, named Archaeornithura meemannae, are the oldest-known examples of Ornithuromorpha, the same evolutionary branch that gave rise to all species of modern birds. The fossils display finely preserved plumage and flight-adapted anatomical features. An absence of feathers on the upper legs of both fossils may indicate the birds made a living as waders, much like modern herons and egrets.
Using stratigraphic and radiometric dating, a team led by Min Wang of the Chinese Academy of Sciences in Beijing found that the two specimens lived during the Early Cretaceous Period, about 130.7 million years ago, predating what had been the oldest-known specimens of this branch from 125 million years ago.
Several other clades of birds also evolved during the Mesozoic, including the Enantiornithes, which are characterized by teeth and clawed wings. However, this group of birds went extinct at the Cretaceous-Paleogene boundary approximately 66 million years ago and is not thought to have any modern descendants.
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