In a groundbreaking study reported on November 21 in Current Biology, researchers Nicholas Longrich of Yale University, Anthony Russell of the University of Calgary, and Jakob Vinther from the University of Bristol delved into the evolutionary history of avian wings, revealing surprising insights into the origins and development of flight among early birds and their dinosaurian relatives.
“By studying fossils carefully, we are now able to start piecing together how the wing evolved,” said Nicholas Longrich of Yale University. “Before, it seemed that we had more or less modern wings from the Jurassic onwards. Now it’s clear that early birds were more primitive and represented transitional forms linking birds to dinosaurs. We can see the wing slowly becoming more advanced as we move from Anchiornis, to Archaeopteryx, to later birds.”
“This makes us rethink the aerial capabilities in the early phases of avian evolution,” added Anthony Russell of the University of Calgary.
What Longrich, Russell, and their colleague Jakob Vinther from the University of Bristol discovered by poring very carefully over the fossil evidence was that neither the wings of bird-like dinosaurs nor the wings of the very early bird Archaeopteryx looked quite like those of modern birds. That is, the feathers on their wings were configured differently.
“Archaeopteryx has this weird design with multiple layers of long flight feathers,” Longrich said. “The dinosaur Anchiornis has tons of simple, strip-like feathers that overlap—the only bird that has anything remotely similar is a penguin.”
That means that early wings probably worked effectively as simple airfoils for gliding, and perhaps for very primitive flapping flight at high speeds, the researchers say. But the feathers on those wings couldn’t separate and twist in the way they do in a modern bird. Low-speed flight and ground takeoff may have been difficult, or even impossible, for them.
“We are starting to get an intricate picture of how feathers and birds evolved from within the dinosaurs,” said Jakob Vinther from the University of Bristol. “We now seem to see that feathers evolved initially for insulation. More complex vaned or pinnate feathers evolved for display. These display feathers turned out to be excellent membranes that could have been utilized for aerial locomotion, which only very late in bird evolution became what we consider flapping flight.”
The study represents a significant step forward in our understanding of avian evolution, highlighting the complexity and gradual nature of the transition from feathered dinosaurs to modern birds. By unraveling the mysteries of wing evolution, researchers continue to piece together the intricate story of life on Earth, uncovering the remarkable adaptations that have allowed birds to conquer the skies for millions of years.
This newfound understanding also sheds light on the broader context of evolution within the dinosaur lineage. Longrich’s work challenges traditional views of dinosaur-bird transitions, emphasizing the nuanced processes involved in the development of flight-related adaptations. Russell echoed this sentiment, stressing the importance of reevaluating existing paradigms in light of new evidence.
Vinther’s contributions to the study provide crucial insights into the multifunctionality of feathers throughout evolutionary history. From their origins as insulation to their role in display and ultimately aerial locomotion, feathers have undergone a remarkable transformation, mirroring the evolutionary journey of avian species.
Source: Cell Press