Sep. 25, 2009 at 7:10 PM ET
Hu Dongyu / University of Bristol
This artwork shows how a birdlike dinosaur known as Anchiornis huxleyi
might have looked in life, more than 150 million years ago.
A recently discovered fossil has led Chinese researchers to conclude that a previously identified dino-bird species was an honest-to-goodness dinosaur. The new findings, laid out in the journal Nature, lend further support to the view that birds really did descend directly from dinosaurs.
Over the past few decades, paleontologists have found increasing evidence that present-day birds and ancient dinosaurs were long-lost cousins: Both sections of the evolutionary tree had species with feathers as well as similar skeletal characteristics. But did dinosaurs give rise to the first bird species, or did the two types of animals spring from a common ancestor that was technically neither a bird nor a dinosaur?
Fossils of a dino-bird species known as Anchiornis huxleyi, which first came to light almost a year ago, play a key role in addressing that big question. At first, researchers thought Anchiornis might have been a transitional species - something that seemed to fall between birds and dinosaurs, or perhaps an early bird like Archaeopteryx. But in the newly published Nature paper, Anchiornis' discoverers say they've found a much better-preserved specimen. The fossils show more clearly that the critter was a four-winged, feathered dinosaur - specifically, a member of the troodontid family.
The fact that Anchiornis (dated at 151 million to 161 million years old) was around long before Archaeopteryx (dated at less than 150 million years old) is used to argue that the features distinguishing early birds were present previously in dinosaurs. The researchers say "this new find refutes the 'temporal paradox'" surrounding the origin of birds.
Predictably, the find is being heralded as a "missing link" in the long-running dino-bird debate. Here are more links that shed light on the discovery:
The researchers behind the Nature study, released online in advance of Oct. 1 in-print publication, are Hu Dongyu, Hou Lianhai, Zhang Lijun and Xu Xing of Shenyang Normal University's Paleontological Institute. Hou and Xu also are affiliated withe the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology.