Image: S. Abramowicz, Dinosaur Institute, NHM.
All paleontological discoveries should be celebrated, but researchers really hit the jackpot with the Changyuraptor yangi. Not only is the 125-year-million-old microraptor the largest flying dinosaur ever unearthed, it also sports two sets of wings. While every dinosaur is a unique snowflake, there's no question that a large airborne raptor decked out with four wings is an extra-special find.
The new species was discovered by an international team of paleontologists led by Luis Chiappe of the Natural History Museum of Los Angeles County. They published their analysis of the specimen in Nature Communications today. Weighing about nine pounds and measuring four feet from head to tail, Changyuraptor yangi was definitely big for a microraptor (as the name of the clade implies, most of its brethren were smaller). Several of these tiny fliers have been discovered during the last decade in Liaoning Province of China, and all of them sport the curious four-wing body configuration.
But Changyuraptor yangi has proved that flying—or at the very least, gliding—was an adaptation that could be obtained by (relatively) bigger dinosaurs as well. “The new fossil documents that dinosaur flight was not limited to very small animals but to dinosaurs of more substantial size,” Chiappe said in a press release. “Clearly far more evidence is needed to understand the nuances of dinosaur flight.”
At this point, a quick clarification is in order. While Changyuraptor yangi is the largest flying dinosaur ever discovered, it was not largest flier of its time. Pterosaurs are often lumped in with the dinosaurs, but they were an entirely separate group of creatures that secured their dominion over the skies in the Triassic. This early start gave pterosaurs a distinct edge over dinosaurian fliers throughout the Mesozoic, until the entire pterosaurian order was snuffed out in the Cretaceous-Paleogene extinction event. So while Changyurpator yangi was testing out its freaky four-wing body plan in the early Cretaceous, pterosaurs like Anhanguera were sporting wingspans of 15 feet. Later on in the Cretaceous, the monster pterosaur known as Quetzalcoatlus northropi evolved a ridiculous 40-foot wingspan, cinching the record for the largest flying animal to this day.
You call that a giant Cretaceous flier? This is a giant Cretaceous flier. Image: Matt Martyniuk (Dinoguy2), Mark Witton, Darren Naish.
This raises the question of whether pterosaurs ever tried on the four-wing configuration for size before microraptors evolved it, in a case of convergent evolution.
"Pterosaurs evolved wings in a very different manner from how dinosaurs did it," paleontologist and co-author Alan Turner explained to me. "They relied on a membrane that was stretched from a very long finger across the arm and then attached to along the body and the lower limb. So the lower limb wasn't really free to evolve its 'own wing' like in microraptorine dinosaurs."
"That said, some pterosaurs, particularly the early ones in pterosaur evolution, had long tails like microraptorines, which often had vanes at the end, like the broad feather fan at the end of the Changyuraptor tail," he continued.
"So as far as the tail is concerned I'd say that this is probably convergent evolution because for both microraptorines and early pterosaurs this tail shape would have been effective at controlling pitch, tilting forward or backwards, and slowing descent."
All of this just goes to show that the Mesozoic had a huge diversity of fliers and gliders, from microraptors like Changyuraptor, to massive pterosaurs, to the late Cretaceous avians—the only dinosaurian lineage that survives them all today.