In DepthPaleontology

When modern birds took flight

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Science  08 May 2015:
Vol. 348, Issue 6235, pp. 617
DOI: 10.1126/science.348.6235.617

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Summary

The first birds arose from dinosaur ancestors about 150 million years ago, but what happened after that has not been clear. The earliest known bird, Archaeopteryx, was probably a poor flier and an evolutionary dead end. But spectacular finds of early birds from northeastern China over the past 15 years or so have started to fill in some of the gaps. These fossils had shown that by 125 million years ago, birds had split into two main groups: one that led to modern birds and another that went extinct at the end of the Cretaceous period 66 million years ago—along with all other dinosaurs. This week, researchers from China report in Nature Communications the discovery of the earliest known relative of modern birds, a 130-million-year-old species they have named Archaeornithura meemannae. These two very well preserved fossils—including the feathers—provide important new insights into how modern birds arose, because the details of their skeletons show that they were waders like today's plovers. This strongly suggests that modern birds evolved in an aquatic environment. Archaeornithura also appears to have been a very able flier, indicating that this key feature behind the success of the modern bird lineage arose very early. The finds push the origins of modern birds back more than just 5 million years, however, because they were already so specialized for wading that these features—including the ability to engage in skillful, wing-powered flight—must have evolved millions of years earlier.