jeholornis

Two-Tailed Ancient Bird Uncovered

An ancient dinosaur-era bird turns out to have two tails, one perhaps for flying and the other for showing off.

by Dan Vergano

The early bird gets two tails? A 120-million-year-old bird sported a long tail and a second, unexpected tail frond, paleontologists suggest. The discovery points to a complicated evolutionary path for the tails we see in birds today.

One of the oldest known birds, Jeholornis, lived in what is today China, along with a trove of other feathered dinosaurs discovered in the region over the last decade. It was also thought to sport only a long fan-feathered tail at its back end. Now, however, paleontologists are claiming discovery of a second tail frond adorning the bird.

"The ‘two-tail’ plumage of Jeholornis is unique,” according to the study, which was led by Jingmai O’Connor of the Chinese Academy of Sciences in Beijing. The report of the discovery of the tail frond was published in the Proceedings of the National Academy of Sciences

(read more: National Geographic)

illustration by Aijuan Shi

Two Tails by Eurwentala:

According to a brand new study publiched in PNAS, Jeholornis prima had two fans of tail feathers: one on the base of the tail, and other on the tail tip. It was suggested the proximal one was for aerodynamic functions, while the frond-like thing on the tail tip was mostly ornamental.

Both the article and the accompanying illustration in National Geographic were pretty horrible, prompting me to go to the original article and try and make sense of it. I’m still not quite sure of I got the proximal feather fan right, but I hope so.

Jeholornis was a primitive bird from the Early Cretaceous of China, about 120 million years ago. They were some of the largest early birds known, reaching adult lengths of up to 80cm (2.6ft).

Several specimens have been found to preserve evidence of a frond of feathers at both the tip and the base of the tail, earning it the nickname of the “two-tailed bird”. Whether this feature served any actual aerodynamic purpose is unclear — much like modern peacocks’ and roosters’ fancy ‘tail’ feathers, it may have been a plume of modified coverts serving as a sexual display feature.

Reconstructions vary on the exact placement of the feathers. The image seen in most news articles was… awkward-looking, and many other artists have chosen to depict the feathers along the side of the tail rather than the top. I’ve put them more dorsally here, in line with the discoverers’ interpretation.

TWO-TAILED ANCIENT BIRD UNCOVERED

Dan Vergano/ Nat Geo

One of the oldest known birds, Jeholornis, lived in what is today China, along with a trove of other feathered dinosaurs discovered in the region over the last decade. It was also thought to sport only a long fan-feathered tail at its back end. Now, however, paleontologists are claiming discovery of a second tail frond adorning the bird

Of 11 Jeholornis fossils that retain evidence of ancient plumage, 6 have signs of this frond of 11 feathers, which would have jutted above the bird’s back at a jaunty, upright angle in a “visually striking” manner, according to the study.

Jeholornisis not thought to be directly related to modern birds, which seem to have evolved from a different line of early avians. The study authors suggest that the tail frond may have played a stabilizing role in the flight of these early birds and that if the arrangement of feathers had proven advantageous enough, modern birds might have evolved to sport such two-tailed features. They see the fronds as flattening to offer a streamlined appearance when the bird was in flight.

Other researchers aren’t convinced the newly discovered tail frond played much of a role in aviation, however.