Scientists discover feathered dinosaur provides more clues to evolution of birds

A creature that looks like a cross between a chicken and a dinosaur is helping paleontologists better understand the link between dinosaurs and modern-day birds.

There's a scientific consensus that birds are descended from dinosaurs, but exactly how their feathers developed and when they began to take flight isn't yet understood. 

• Archaeopteryx's feathery details revealed by fossil
• Feathered dinosaur tail found trapped in amber
• Dinosaurs of a feather flocked together, study finds

Now, a team of scientists from Canada and China has discovered a new species of feathered troodontid dinosaur, the Jianianhualong tengi, believed to have lived about 125 million years ago. Troodontids are believed to be the closest relative to birds.

"Troodontids are interesting because we need to understand their evolution history if we're to fully understand how birds evolved, how their flight evolved," said Michael Pittman, from the University of Hong Kong and co-author of the paper published in Nature on Tuesday.

I think there are a lot of surprises out there yet for us.- Phillip Currie, paleontologist

Though the feathers are asymmetrical, the researchers don't believe Jianianhualong Tengi flew. Instead, it may have used its feathers in other ways, such as as a sexual display or to warm eggs in nests. The feathers also gave it an aerodynamic advantage, perhaps allowing it to quickly flee from predators.

The fossil was discovered in northeastern China four years ago. Just as the Alberta's Badlands is known in Canada for its rich dinosaur fossils, China is a hotbed of incredibly well-preserved fossils.

More to be discovered

While there are still some missing gaps, the researchers said they're moving forward to fill them in. 

"In a way this gives us some answers and some clues, and in other ways, it says … there's something else going on,"  said Philip Currie, a paleontologist at the University of Alberta and another author of the paper.

"It's not a black and white thing where asymmetrical feathers indicated they were flying animals, and symmetrical feathers indicated they're not flying animals. It's not that simple. It's a cautionary tale in part, and it's also one more piece in the puzzle."

The researchers also found it interesting that Jianianhualong Tengi showed something called mosaic evolution, whereby parts of the bodies evolve without simultaneously affecting other parts. For example, its forelimbs resembled those of early troodontids, but its legs resembled later troodontids. 

The research serves as a reminder that there are far more species of dinosaurs waiting to be discovered.

"For a long time, we thought we knew a lot of dinosaurs, but we don't," Currie said.

"I don't think we've discovered more than one per cent of one per cent of the dinosaur species that lived," he said. "They were incredibly diverse animals …. When you think we know somewhere between 1,200 and 1,500 dinosaurs worldwide for 150 million years, we know nothing."