‘Weird’ dinosaur prompts rethink of fowl evolution

One hundred and fifty million years in the past, a younger, bantam-sized, bird-like dinosaur grew to become mired in a swamp in what’s now southeastern China, and succumbed. Its fossilized stays, unearthed in 2022 and named Fujianvenator prodigiosus, present it to be one of many earliest bird-like dinosaurs up to now from the Jurassic interval. The researchers describe their discovery in a paper revealed right now in Nature¹.

“This is really a weird animal within the group of birds,” says Mark Loewen, a palaeontologist on the University of Utah in Salt Lake City, who was not concerned within the discovery.

The creature had oddly lanky legs and may need lacked the flexibility to fly. It additionally would not appear to evolve to the accepted bird-evolution story.

Although dinosaurs had been largely extinct by 66 million years in the past, therapods, the three-clawed, hollow-boned group that included Velociraptor and Tyrannosaurus rex, had began to evolve into right now’s birds. Many palaeontologists think about the primary fowl to be a 150-million-year-old feathered dinosaur referred to as Archaeopteryx, fossils of which had been present in Germany. But this examine provides to mounting proof that by the point of Archaeopteryx, dinosaurs had already diversified into completely different sorts of birds, Loewen says.

Hailu You, a palaeontologist on the Chinese Academy of Sciences in Beijing and one of many co-authors of the paper, says that within the Jurassic, bird-like dinosaurs may need been occupying completely different ecological niches. “Early bird evolution is complicated,” he says.

Fujianvenator’s fossil lacks a head or an entire tail, however its physique and limbs present a medley of traits much like these of different bird-like dinosaurs, such because the relative lengths of the fingers, and particulars of the pelvis and vertebrae.

But it didn’t have many modifications that will contribute to flight. For instance, it had a shortened shoulder blade and fingers extra specialised for grabbing. Strangest of all are the fowl’s hyper-elongated hind legs, by which the decrease leg bone — the tibia — is twice so long as the thigh bone. Such lengthy legs point out a extremely expert runner, maybe much like a roadrunner (Geococcyx spp.), says Bhart-Anjan Bhullar, a palaeontologist at Yale University in New Haven, Connecticut.

Alternatively, these stilts might have been used for wading. In the world the place Fujianvenator was discovered, the researchers additionally uncovered quite a lot of swamp creatures, which they name the Zhenghe fauna. These fossils included fish, turtles and different aquatic reptiles. Swamps had been a beforehand unknown habitat for early birds. To know whether or not the fowl’s legginess was an adaptation to swamp life or high-speed working, researchers would want to look at the ends of its toes for indicators of webbing — however these digits are poorly preserved. Either situation is equally potential, the authors write.

The incontrovertible fact that the dinosaur was discovered in any respect was a stroke of luck. Researchers uncovered the fossil at a website close to Nanping in Fujian province, the place no dinosaurs have been discovered earlier than. And examples of late-Jurassic bird-like dinosaurs are uncommon as a result of their hole bones are fragile and protect much less effectively. Fossilization requires very best situations such an absence of oxygen to stop decay — situations that lakes or swamps can present.

Because of that shortage of fossils, Fujianvenator helps to fill in some gaps in early fowl evolution, says Bhullar. “Even at their earliest stages, the closest fossil relatives of birds were diversifying in interesting ways.”

“There are many, many such things left to be discovered,” he says. “We’ve only scratched the surface of the anatomical and lifestyle diversity of these animals.”