Fossils reveal some feathered dinosaurs lost the ability to fly
A Tel Aviv University–led study of 160-million-year-old fossils shows that some feathered dinosaurs likely became flightless, challenging the idea that the evolution of flight followed a linear path
A rare fossil discovery is reshaping scientists’ understanding of how flight evolved in dinosaurs and birds. Researchers have found that some feathered dinosaurs may have lost the ability to fly, challenging the long-held assumption that flight evolved in a straightforward, linear way.
The findings come from a new international study led by Tel Aviv University and published in Communications Biology, a journal of the Nature group. The research was headed by Dr. Yosef Kiat of Tel Aviv University’s School of Zoology and the Steinhardt Museum of Natural History, in collaboration with scientists from China and the United States.
The study examined nine exceptionally preserved fossils dating back about 160 million years.
The fossils, discovered in eastern China, belong to Anchiornis, a small feathered dinosaur considered a distant relative of modern birds. Remarkably, the specimens retain not only their feathers but also traces of their original coloration.
The wings of Anchiornis show white feathers tipped with black markings—details that allowed researchers to analyze the animals’ molting patterns. Molting, the process by which feathers are replaced, is closely linked to flight ability. In flying birds, feather replacement follows a symmetrical and orderly pattern that allows them to remain airborne. In flightless birds, molting tends to be irregular.
Analysis of the fossils revealed that Anchiornis exhibited an uneven molting pattern, similar to that seen in modern flightless birds such as ostriches and penguins. This suggests that despite having wings and feathers, these dinosaurs were likely incapable of sustained flight.
Dr. Kiat said the findings point to a more complex evolutionary picture, in which some dinosaur species may have developed early flight capabilities only to lose them later as their environments changed. “Even small details like molting patterns can dramatically change how we understand the origins of flight,” he said.
The discovery underscores that feathers did not automatically confer flight and highlights the diverse evolutionary paths that ultimately led to modern birds.