Fossil and restoration of the newly found Ambopteryx longibrachium Photo: Courtesy of Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology. (Photo: Global Times)

From a 163 million-year-old fossil, Chinese scientists recently discovered the arduous and unexpected journey of the evolution of flight from dinosaurs to birds.

Scientists at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences found that the fossils of a dinosaur from the Upper Jurassic strata in Northeast China's Liaoning Province had feathers and membranous tissues, according to a statement the institute sent to Global Times on Thursday. 

Experts hailed the discovery as "solid evidence" of the existence of dinosaurs with feathers and bat-like membranous wings, something new in evolutionary history.  

The discovery appeared on Nature's cover on Wednesday.  

The newly found species, named Ambopteryx longibrachium, which the scientists believe belongs to a new type of Scansoriopterygidae, had long "arm" bones (humerus and ulna) for the membrane to attach, which is different from avian dinosaurs with longer "finger" bones (metacarpals) for the feathers, according to the statement. The avian lineage later evolved into birds. 

Why would a dinosaur develop both bird feathers and membranous wings to fly, which seems to be inefficient?

That's why they got extinct, Xing Lida, a dinosaur footprints expert at Beijing-based China University of Geosciences, said jokingly.  Such a hybrid structure suggested dinosaurs had tried multiple paths in attempts to fly because it did not know which one would succeed, Xing told the Global Times. 

But the structure was short-lived, meaning the dinosaurs had "made detours in their evolution to birds," Xing said, noting the evolution was far more complicated than a linear process.

In the race between a short "finger bone" with bat-like wings and long "palm bone" with feathered wings, the membranous one from the Jurassic era did not survive into the Cretaceous era, Wang Min, research fellow with IVPP and corresponding author of the Nature article, told the Global Times on Thursday.  

In contrast, feathered wings, first documented in Late Jurassic non-avian dinosaurs, were further refined through numerous skeletal and soft tissue modifications. Such modifications ultimately lead to the current success of modern birds.

When the IVPP team first discovered the fossil in 2017, it was unclear whether it was a bird or a dinosaur. But after restoration, the fossil was determined to be of a feathered dinosaur with membranous wings, said Wang. 

Such a combined structure was first recognized in 2015 by the same team and named Yi qi, which means "strange wings" in Chinese. But Yi qi's forelimb was detached from its body while the newly found dinosaur fossil was better preserved and clearly showed its feathers and membranous tissues, Wang said. 

It is really fortunate to discover this dinosaur four years after Yi qi, which an ancient volcano eruption preserved rich information of species living then, he said.