New research is challenging long-held assumptions about how flight evolved in dinosaurs and birds, according to a study published on Tuesday in Communications Biology.
Yosef Kiat of Tel Aviv University’s School of Zoology and the Steinhardt Museum of Natural History led an international team that examined 160-million-year-old fossils and found that some feathered dinosaurs had lost the ability to fly—suggesting the path to flight was more complex than scientists believed.
The research focused on nine exceptionally preserved fossils of Anchiornis, a feathered dinosaur species from eastern China. The fossils showed white wing feathers with black tips, details that proved crucial to the discovery.
Kiat used his expertise in modern bird feather patterns to analyze the specimens and identified irregular molting, similar to that seen in flightless birds such as ostriches and penguins.
“Feather molting seems like a small technical detail—but when examined in fossils, it can change everything we thought about the origins of flight,” said Kiat.
Birds that fly molt gradually to maintain wing symmetry, while flightless birds molt irregularly. By tracking new feather growth and deviations in the black spot pattern, researchers concluded Anchiornis molted irregularly, meaning it could not fly.
The discovery adds Anchiornis to a growing list of feathered but flightless dinosaurs, showing that some species may have developed early flight abilities and later lost them as conditions changed.
“This is a rare and especially exciting finding,” said Kiat. “The preserved coloration of the feathers gave us a unique opportunity to identify a functional trait of these ancient creatures, not only their skeletal structure.”
The study, conducted with scientists from China and the United States, highlights the complexity and diversity of wing evolution among dinosaurs and early birds.
