Yixianornis

Yixianornis is one of the best-preserved bird fossils from the Jehol group, with bones that are mostly uncrushed and clear impressions of wing and tail feathers.1

Its tail feathers were arranged in a graduated series, with the outer feathers anchored closer to the base of the tail, giving it a rounded silhouette.1

Yixianornis had a rectrical bulb, a muscle that allows tail feathers to be fanned out during flight and retracted when at rest, just like in modern birds.1

The tips of its jaws were toothless and had small pits and grooves, possibly indicating the presence of a beak.1

Its flight feathers were very broad and rounded, not narrow and pointed like in many other early birds.1

Scientists think Yixianornis was diurnal, meaning it was active during the day, similar to most modern birds.1

Yixianornis is the most primitive bird known to have an essentially modern pygostyle and fan of tail feathers.1