Why Did Birds Lose Their Tails?: Zhengheornis buyu

Publication Info:

Transcript:

Min Wang et al, Jurassic avialan reveals stepwise evolution of bony tail in birds, Science Advances (2026). DOI: 10.1126/sciadv.aeb5202

Meet Zhengheornis buyu, the brand new transitional bird fossil from Jurassic China! 🦖🦜 150 million years ago this relative of dinosaurs like velociraptor and modern birds was doing some weird things with its tail!

Episode 305

Notes:

Have you ever wondered how this became this? Here's your most recent paleontology news almost daily or whenever I get around to it. Yeah, don't worry. I can already hear all the people who don't understand how examples work typing T-Rex did not become a chicken. But non-avian dinosaurs theropods did become birds, specifically the lineage that's much more closely related to things like Velociraptor. So you might be thinking why doesn't Velociraptor look more like a bird? And that's because this isn't Velociraptor. This is. But it's still kind of a good question because obviously non-avian dinosaurs, even the theropods, have some very non-bird-like features at least compared to modern birds like teeth and a long muscular tail where modern birds have what's called a pygostyle which it's thought to probably be helpful with flight where the last few vertebrae are fused together a little more like our tailbone than what you really expect to see in any other reptiles. And that obviously means that at some point dinosaurs went from a long muscular tail to a short fused pygostyle. And because of how evolution works, there should be transitional animals. Keep in mind, that doesn't mean there will always be transitional fossils. Fossils are relatively rare. But now, luckily in this case there there are. Meet Zhengheornis buyu,, the newly named late Jurassic bird from China. It's a basal avialan and it's special not just in the way that every animal is special. It has a very special tail because 150 million years ago its close non-avian relatives still had long muscular tails with something like 30-plus vertebrae. It still doesn't have a pygostyle, but it does have a significantly reduced tail with only about 15 vertebrae. Making a really strong case for it being somewhere in the transition between tail and no tail. As usual, if you want more information, here's the source.