The newly discovered Yuanchuavis is named after the Yuanchu bird from Chinese mythology. Credit: Provided

CHICAGO — A Field Museum paleontologist is playing a role in the discovery of a more than 100-million-year-old fossil of a flashy bird with flowing tail feathers that say a lot about its ability to survive.

The Field Museum’s Jingmai O’Connor is co-author on a new study in “Current Biology” magazine where scientists analyze the discovery of the fossil bird in northeastern China. With tail feathers longer than its body, the bird is making a stir in the scientific world.

“We’ve never seen this combination of different kinds of tail feathers before in a fossil bird,” O’Connor said in a statement from The Field Museum.

Named Yuanchuavis by researchers after the Yuanchu bird of Chinese mythology, the fossil was discovered in northeastern China in 120-million year-old Early Cretaceous period volcanic deposits.

Yuanchuavis was a small bird, about the size of a blue jay, and its tail was more than 150 percent of its body length. According to O’Connor and other scientists, there are other things about the prehistoric bird that make the fossil a notable find. 

“It had a fan of short feathers at the base and then two extremely long plumes,” O’Connor said. “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.”

Researchers also said the tail gives good clues about Yuanchuavis’ life, the time period it lived in and its reproductive capabilities. 

“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,” O’Connor said. “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.’”

A scientific rendering shows the different parts of the Yuanchuavis body, including what its fancy tail feathers may have looked like. Credit: Provided

O’Connor also hypothesizes the bird, because of its elaborate feathers, probably lived in a dense, resource-rich environment like a forest, as some birds with similar long tail feathers — ones less aerodynamic and specialized for flight — tended to settle. 

Yuanchuavis males also probably were less involved in child rearing than their female counterparts as flashy feathers often require lots of energy and resources to maintain. They can also lure unwanted predators to nest. That means less time to care for young, which often falls to the less-colorfully plumed partner. 

Discovering more fossils of ancient birds like Yuanchuavis, which went extinct with the dinosaurs, can add to what experts like O’Connor can learn about today’s birds.

“The complexity we see in Yuanchuavis’s feathers is related to one of the reasons we hypothesize why living birds are so incredibly diverse, because they can separate themselves into different species just by differences in plumage and differences in song,” O’Connor said. 

“It’s amazing that Yuanchuavis lets us hypothesize that that kind of plumage complexity may already have been present in the Early Cretaceous.”

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