The First Flightless Bird: Yuezhuornis yangyuanensis

Publication Info:

Transcript:

L. Xu et al. 2026. Jurassic flightless bird reveals early ecological diversity of avialans. Nature 658, 690-697; doi: 10.1038/s41586-026-10972-z

Meet Yuezhuornis yangyuanensis!
This new dinosaur... is actually a bird. Despite looking a lot like many of its non avian dinosaur relatives, Yuezhuornis is an early bird, with teeth, raptor-like sickle claws, and a tail!. It also couldn't fly 🤯 that might not sound like a big deal, but it adds a confusing element into the evolution from non avain dinosaur to true birds.

Episode 360

Notes:

This is Yuezhuornis yangyuanensis, the crow-sized dinosaur from late Jurassic China. And like I said, it was about the size of a crow. It had feathers. It also had teeth and claws like a Deinonychus or Velociraptor and very short forelimbs. At a glance, it would have looked a whole lot like Dromaeosaurus like Velociraptor or Deinonychus. It would have even been Flightless. But it wasn't a raptor, at least not in that sense. It was a true avialan, meaning that it was a member of the same group as modern birds and their closest relative. Meaning that Yuezhuornis was a feathered, tailed, clawed, toothed, early flightless bird on an early branch of the bird family tree like animals like Archaeopteryx. And it was even a sister taxon to Xiangornis. Which seeing that paleontologists are pretty sure Archaeopteryx could fly brings up a very interesting question. Does it mean there was something weird going on and these different groups were evolving flight at different rates or does it mean that some groups had already started to lose the ability to fly? Which sounds weird but also seems to be something birds like doing. As usual, if you want more information, here's the source.