Ancient Aura Farming? 121-Million-Year-Old Bird Had A Gigantic Tail, Possibly To Impress Mates

A newly identified ancient bird species that lived about 121 million years ago sported a pair of tail feathers so absurdly long they stretched to nearly twice the length of its entire body. Scientists believe those feathers probably weren’t for flying. They may have helped the bird stand out during displays, perhaps in courtship.

Researchers have formally described Plumadraco bankoorum, a crow-to-thrush-sized bird that lived during the Early Cretaceous period in what is now northeastern China. The fossil, recovered from a rock formation in Liaoning Province, is remarkably intact, with bones, body feathers, wing feathers, and most strikingly, a pair of ornamental tail feathers preserved in exceptional detail. Those tail feathers, measuring nearly twice the creature’s body length, are the proportionally longest ever recorded in its group, and their fine preservation offers strong clues about what the bird may have been doing with them.

Plumadraco belongs to a group of extinct birds called enantiornithines, the most diverse and widespread birds of the Cretaceous period, with over 100 known species found on every continent except Antarctica. These birds ruled the skies alongside dinosaurs for tens of millions of years before vanishing at the end of the Cretaceous.

What Is Plumadraco bankoorum, the Ancient ‘Feather Dragon’ Bird?

Named for its most dramatic feature, Plumadraco comes from the Latin words for “feather” and “dragon.” Its species name, bankoorum, honors Winston E. and Paul C. Banko, two researchers whose work contributed significantly to the understanding of bird biology and conservation in Hawaii.

Preserved as a complete, connected skeleton on a single slab of rock, the fossil is a rarity in paleontology. Its tail feathers alone measure 293 millimeters, while the body length comes in at 149 millimeters. Previous record-holders in this group had tail feathers reaching only about 1.6 times body length. Plumadraco surpasses that at nearly 1.97 times.

These tail feathers belong to a type of ornamental feather unique to enantiornithines and a handful of their relatives. Unlike modern flight feathers, which have a solid, tube-like central shaft, these ancient feathers had a different, open internal structure that created drag rather than lift, making them a liability in the air and likely an asset on the ground.

Built to Show Off: How Plumadraco Used Its Spectacular Tail Feathers

What makes this fossil especially exciting is not just the feathers’ length but how well-preserved they are. For the first time, researchers can examine the complete structure of one of these tail feathers from base to tip, something no previously discovered specimen in this group made possible.

Near the tips of each tail feather, the central shaft gradually tapers and stops partway into the feather’s decorative, paddle-shaped end. That weakening makes the tip more flexible. When the bird raised its tail during a display, the stiffer base would move first, while the looser paddle at the tip would lag behind and snap forward, creating a flickering, eye-catching motion. Scientists see the same design at work in the ornamental rump feathers of peacocks today.

A chemical scan of the fossil found that body and wing feathers carried higher levels of pigment-linked elements than the tail feathers did, pointing to possible color differences across the bird’s plumage.

Why Scientists Think These Tail Feathers Were About Sexual Selection

Researchers make a careful but tentative argument that these extraordinary tail feathers were likely linked to sexual selection, though they acknowledge the evolutionary drivers are difficult to pin down.

Their case draws on several lines of evidence. Among early Cretaceous birds for which multiple feather-preserving fossils exist, ornamental tail feathers appear in roughly 40 to 60 percent of individuals, consistent with a trait present in only one sex. Enantiornithines also grew their ornamental feathers before reaching full adult size, suggesting these feathers carried real biological costs early in life. Studies on living birds have shown that artificially lengthening male tail feathers increases breeding success, pointing to females actively favoring longer tails when selecting mates.

Based on limited nest fossils, some enantiornithines appear to have nested on open ground. If Plumadraco or its relatives did the same, that would fit the pattern seen in modern open-ground nesters, where males carry the flashy plumage and females stay inconspicuous to avoid drawing predators to the nest.

Publishing in PLOS ONE, the researchers suggest the specimen may have been male and that its spectacular tail was shaped by sexual selection and used in courtship displays, while noting that more evidence is still needed to confirm it.

A Glimpse at an Ancient Arms Race

Plumadraco is not an isolated case. Ornamental tail feathers appear again and again in the enantiornithine fossil record, spanning at least 30 million years across nearly every continent, with each species apparently sporting its own variation in shape, length, and flexibility.

Growing something extravagant and moving it in exactly the right way to attract a mate may not be a modern invention at all. It was possibly playing out in the ancient forests of China more than 120 million years ago, long before any bird alive today ever existed.

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