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Some of the first birds were terrible at the one thing birds are famous for. Scientists have discovered the fossil of a crow-sized bird that lived in China roughly 150 million years ago with wings so undersized it may have been more of a runner than a flier, according to Reuters. Named Yuezhuornis yangyuanensis, the Jurassic species is scrambling what paleontologists thought they knew about how the avian body plan evolved.
A roadrunner from the Jurassic
The nearly complete fossil was unearthed in Fujian Province in southeastern China and described in a study published in the journal Nature. Yuezhuornis is roughly the same age as the famous Archaeopteryx from Europe, making it one of the earliest-known birds — yet it seems to have already diminished its ability to fly in favor of running on the ground. Asked whether it may have lived like a modern roadrunner — a fast runner but clumsy flier that rarely takes to the air — paleontologist Min Wang of the Institute of Vertebrate Paleontology and Paleoanthropology, who helped lead the study, answered simply: that is likely.
Why it upends the textbook story
The traditional assumption was that the bird body plan evolved almost exclusively under the selective pressures of flight — wings got bigger and better in a straight march toward the sky. Yuezhuornis breaks that story. "Yuezhuornis challenges the traditional paradigm that the avian body plan evolved almost exclusively under the selective pressures of flight," Wang said. University of Edinburgh paleontologist Steve Brusatte, who was not involved in the study, called it one of those discoveries that raises more questions than it answers: one of the oldest and most primitive birds on the family tree, yet with a skeleton he described as a mashup of avian and dinosaurian traits. Some of the first birds, it seems, were experimenting with giving flight up almost as soon as evolution had invented it.
Fujian: the new fossil frontier
There is a reason this bird turned up in Fujian and not in the famous Liaoning fossil beds farther north. The Zhenghe fauna of Fujian Province — dating to roughly 150 million years ago — is emerging as one of the richest windows into the Jurassic world, preserving feathered dinosaurs, early birds and mammals in exceptional detail. Each new species from these rocks seems to break a rule the Liaoning fossils established. If Yuezhuornis is any indication, the Fujian beds still hold more heresies: the early evolution of birds may have been less a ladder toward flight than a bush of experiments, most of which left no descendants.
What comes next
The Fujian fossil beds are still young as a scientific frontier, and Yuezhuornis is unlikely to be the last surprise they hold. Each new early bird fills in the most poorly documented chapter of avian evolution — the few million years when feathered dinosaurs were becoming birds, and apparently trying every body plan at once. If flight could be lost this early, the road to the modern bird was far more winding than the textbooks suggest. Follow Global Insight for the discoveries rewriting natural history — from the Jurassic swimmer Megacauda to the planet reborn from a dead star.