A 150-million-year-old fossil discovery in China has rewritten a central page in the book of avian evolution. The fossil, Baminornis zhenghensis, is a bird that bears a mix of dinosaurian and modern features. This find challenges the long-held notion that Archaeopteryx was the sole representative of Jurassic-era birds.
Baminornis possesses a fused pygostyle, a compound tailbone that supports fan-shaped tail feathers, unlike its counterpart Archaeopteryx, which has a long, reptilian tail. This adaptation is central to modern birds’ aerodynamic efficiency and allows for more agile flight. The fossil suggests that birds diversified much earlier than previously thought.
The discovery also raises questions about how and when key flight adaptations emerged. Researchers now propose that the origin of modern bird characteristics can be traced back nearly 20 million years earlier than previously believed.
These findings are forcing paleontologists to reevaluate their understanding of Jurassic avifauna. The emerging consensus is that while Archaeopteryx should remain a critical specimen, it may represent just one branch of an early bird tree whose members have been lost to the past.
The contrast between Archaeopteryx and Baminornis highlights the complexity of the transition from dinosaurs to modern birds. The evolution of flight-related adaptations was not linear but rather a branching pathway marked by experimentation and rapid diversification.
A newly discovered fossilized wishbone, which is believed to belong to an early bird species, has also been found in the same excavation as Baminornis. This discovery bolsters the argument that modern bird features began earlier than previously thought.
The findings herald a seismic shift in our understanding of bird evolution, revealing that the roots of modern birds extend deeper into the Jurassic period than ever imagined. For evolutionary biologists, this opens new windows into the past, compelling us to reexamine the processes and selective pressures that gave rise to flight, refined locomotion, and ultimately, the unparalleled diversity of birds today.
Source: https://www.forbes.com/sites/scotttravers/2025/02/23/new-150-million-year-old-fossil-has-rewritten-the-history-of-bird-evolution-a-biologist-explains