A study led by Tel Aviv University shows that feathered dinosaurs from the group Peneraptor evolved wings but likely lost the ability to fly, a discovery that further complicates the story of the origin of birds.
Not everyone with wings can fly. The kiwi, the ostrich, and the penguin are living proof of this. New research from Tel Aviv University takes us back 160 million years to the Jurassic period, and reveals that this phenomenon began with feathered dinosaurs. In extremely rare fossils discovered in eastern China, not only dinosaur skeletons were preserved but also their wing feathers, and even their color. An in-depth analysis of the find reveals a surprising discovery: those dinosaurs were indeed equipped with feathers, but they apparently lost the ability to fly. The research team emphasizes that this find has broad significance, as it indicates that the development of flight throughout the evolutionary process of birds and dinosaurs was much more complex than previously thought. In fact, certain species may have developed basic flight capabilities — and then lost them later in evolution.
They made them wings.
The study was led by Dr. Youssef Khayat from the School of Zoology in the George S. Wise Faculty of Life Sciences, and fromSteinhardt Museum of Nature, in collaboration with researchers from China and the United States, and was published in the journal Communications Biology from Nature. According to the researchers, this is an extremely rare find that allows an extraordinary glimpse not only into the body structure of ancient creatures, but also into how they function.
To understand the magnitude of the surprise, we need to go back to the beginning. Dr. Khyat, an ornithologist (bird researcher) who specializes in the study of feathers, explains: "The dinosaur lineage separated from the rest of the reptiles 240 million years ago. A relatively short time later (on an evolutionary scale) many of the dinosaurs developed feathers – a unique, light and strong organic structure made of protein and used mainly for flight and body heat conservation. About 175 million years ago, a lineage of feathered dinosaurs called 'Peneraptoria' was founded, from which modern birds evolved – the only branch that survived the mass extinction that ended the Mesozoic era 66 million years ago, in which most other dinosaurs became extinct. "As far as we know, the Panraptor group evolved feathers for flight purposes, but it is possible that when conditions changed, some of these dinosaurs lost the ability to fly - similar to modern-day ostriches and penguins."
The feathers that waited 160 million years to tell a story
At the heart of the study are nine fossils of a small dinosaur called Anchiornis, which belongs to the group of Panraptor. The unusual fossilization conditions in the area where they were found allowed for the exceptionally rare preservation of the soft tissues, including the wing feathers. But what made the find truly exceptional was the fact that even the color of the feathers was preserved: white, with a black spot at the tip, a clear pattern that repeats along the edge of the wing.
This is where a seemingly minor detail comes into play, but it turns out to be critical: feather replacement. "Feathers grow for two to three weeks until they reach their intended size, then they detach from the blood vessels that nourish them during growth and become dead material. Over time, they wear out, fall out, and are replaced by new feathers. The process of replacing feathers tells an important story: winged animals that depend on flight, and on the feathers that enable it, replace their feathers in an orderly and gradual process that maintains the symmetry between the wings and allows them to continue flying even during this time. In contrast, in birds without the ability to fly, the process of replacing feathers is more random and disorderly. Therefore, the way in which feathers are replaced tells us whether that winged animal is capable of flying," explains Dr. Khiat.
The colors preserved in the fossils allowed the researchers to identify new feathers that had not yet fully grown, those whose black spot at the tip deviated from the uniform stripe. Close examination of those feathers in the nine fossils revealed a clear pattern: the replacement of feathers did not occur in an orderly and symmetrical manner.
"Based on my familiarity with modern birds, I recognized the pattern of feather replacement that indicated that these dinosaurs had likely lost the ability to fly. This is a particularly rare and exciting find: the preservation of the color of the feathers gave us a unique opportunity to identify a functional feature of these ancient creatures, and not just the body structure preserved in fossils that include skeletons and bones," says Dr. Khiat, concluding, "Feather shedding seems like a small technical detail, but when examined in fossils, it can change everything we thought about the origin of flight. Anchiornis now joins the list of dinosaurs that were covered in feathers but did not fly, and highlights how complex and diverse the evolution of the wing was."
More of the topic in Hayadan:
