The fossil of Plumadraco bankoorum. Credit: Clark et al.

“Peacocking” gets its name from one of nature’s most famous show-offs. But the behavior may be much older than peacocks—old enough to trace back to the age of the dinosaurs.

A 121-million-year-old fossil from China shows that extreme feather displays are not a modern bird invention. Plumadraco bankoorum had two tail feathers nearly twice its body length—likely useless for flight and costly to carry—suggesting that courtship was already pushing some early birds into strange, risky forms.

A Hidden Show-Off

Alex Clark, a Ph.D. candidate at the Field Museum and the University of Chicago, found the fossil during a research visit to China’s Shandong Tianyu Museum. It had been sitting among hundreds of fossil birds.

“I saw this little guy, and I did a double-take when I saw the tail feathers,” Clark said in a Field Museum statement. “I’m really interested in the way birds do displays to attract mates, and I thought that these tail feathers were so crazy, they had to be used for something like that.”

The bird belonged to the enantiornithines, an extinct group that once formed the most diverse branch of Cretaceous birds. They lived alongside non-avian dinosaurs and vanished with them 66 million years ago. Modern birds are the only dinosaurs that survived.

The new species’ name means “Banko’s feathered dragon,” honoring Winston and Paul Banko, father-and-son avian biologists known for work on Hawaiian birds.

“Plumadraco was the size of an American robin, but its tail feathers were about a foot long, twice the length of its body,” Clark added. “They’re some of the proportionally longest tail feathers ever found in a fossil bird.”

Glamorous Purposes

Spectrometry scan of the fossil. Credit: Clark et al.

The fossil preserved body feathers from head to ankles, wing feathers, and the two extraordinary tail plumes. The research team photographed and measured the specimen, then used a handheld mass spectrometer to read chemical traces in the fossil.

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Those traces suggest the feathers were dark brown or black. The tips may have flashed blue or iridescent colors, though those shades often come from microscopic feather structure rather than pigment, leaving less direct chemical evidence.

The tail feathers were useless for flight. They were too long, narrow and drag-heavy to help much in the air. Instead, their structure points toward display, driven by sexual selection.

The stiff central shaft narrowed near the ends, making the tips more flexible. If the bird lifted and lowered its tail, the ends may have swayed or flickered. Modern peacocks and birds-of-paradise use similar visual tricks, turning movement into a signal.

“With this specimen, we have a pretty strong argument that not only did probable males try to attract females with feather ornamentation, but they also did so with ridiculous lengths, and probably displays,” Clark noted.

Scientists cannot prove the fossil was male. Sex organs almost never fossilize. But in living birds, very long ornamental feathers are often male traits, especially when used to court females. Other fossils from the same extinct bird group suggest the tail had a simple but useful range of motion: it could move up and down, enough to make the thin tips tremble behind the body.

Prehistoric Pretty Privilege

Artistic reconstruction of a male and female Plumadraco. Credit: Ville Sinkkonen

All of this puts Plumadraco in a long line of birds whose bodies carry the costs of seduction. Peacocks, birds-of-paradise, and many other modern species show the same trade-off: features that can be awkward, conspicuous, or energetically expensive, but still persist because they help animals reproduce.

The peacock did not invent “peacocking.” It inherited a much older strategy.

The study was published in the journal PLOS One.