Scientists have uncovered a prehistoric “peacock” with a big tail that evolved for mating purposes rather than flight and coexisted with dinosaurs. The species is around the size of a blue jay, with a tail roughly twice the length of its body, making the flight more challenging.

Due to the fact that many bird species have complex mating calls in which they bustle their tail feathers and shake to impress prospective partners, this species is likely one of the oldest birds to have evolved for appearance and sexual motives.

The fossil was discovered in 120 million-year-old early Cretaceous strata in northern China and was called Yuanchavis after a mythological bird. At its base, the bird possessed a fan of small feathers and two exceptionally long plumes called pintails, which are still found in some modern birds such as sunbirds and quetzals.

Coexisting with dinosaurs

Yuanchuavis is an enantiornithine, a member of a group that flourished during the dinosaur era but perished along with them. According to the researchers, the discovery demonstrates how, even in their earliest evolution, natural selection has to consider sexual selection.

“It had a fan of short feathers at the base and then two extremely long plumes. The long feathers were dominated by the central spine, called the rachis, and then plumed at the end. The combination of a short tail fan with two long feathers is called a pintail, we see it in some modern birds like sunbirds and quetzals,” said Dr. Jingmai O’Connor, a paleontologist at Chicago’s Field Museum in a media release.

“Scientists call a trait like a big fancy tail an ‘honest signal’ because it is detrimental, so if an animal with it is able to survive with that handicap, that’s a sign that it’s really fit. A female bird would look at a male with goofily burdensome tail feathers and think, ‘Dang if he’s able to survive even with such a ridiculous tail, he must have really good genes,’” Dr. O’Connor explained.

Finding the key to surviving extinction?

“Understanding why living birds are the most successful group of vertebrates on land today is an extremely important evolutionary question because whatever it was that allowed them to be so successful probably also allowed them to survive a giant meteor hitting the planet when all other birds and dinosaurs went extinct,” the researcher added.

“This new discovery vividly demonstrates how the interplay between natural and sexual selections shaped birds’ tails from their earliest history. Yuanchuavis is the first documented occurrence of a pintail in Enantiornithes, the most successful group of Mesozoic birds,” added Dr. Wing Man, a researcher at the Chinese Academy of Sciences.

“It is well known that sexual selection plays a central role in speciation and recognition in modern birds, attesting to the enormous extravagant feathers, ornaments, vocals, and dances. However, it is notoriously difficult to tell if a given fossilized structure is shaped by sexual selection, considering the imperfect nature of the fossil record. Therefore, the well-preserved tail feathers in this new fossil bird provide great new information about how sexual selection has shaped the avian tail from their earliest stage.”

The findings were published in the journal Current Biology.

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