A very interesting article about the new bird/dinosaur relative Aurornis xui was published this week in the British journal Nature. It can be found at the Nature News Web site, here: http://www.nature.com/news/new-contender-for-first-bird-1.13088.
Apparently, A. xui is a strong contender for “earliest bird”. The extremely complete specimen was unearthed by a farmer in China’s Liaoning Province and acquired by the Fossil and Geology Park in Yizhou, China, through a fossil dealer, where it remained unidentified until being discovered by paleontologist Pascal Godefroit in 2012.
The article states that Godefroit believes that A. xui is “the oldest known member of the Avialae,” the group that includes all animals more closely related to modern birds than to dinosaurs. This makes it the oldest bird, even older than Archaeopteryx. A phylogenetic comparison of the specimen with approximately 100 other birds and dinosaurs seems to confirm this.
Godefroit goes on to say, “But these sorts of hypotheses are very controversial. We’re at the origins of a group. The differences between birds and [non-avian] dinosaurs are very thin.”
The American journal Science, also has an article about the find, which can be viewed here: http://news.sciencemag.org/sciencenow/2013/05/earliest-bird-claim-ruffles-feat.html. This article provides some additional background information about the evolutionary history of birds and dinosaurs. It also points out the key remaining issue with the find – it’s authenticity. There have been several famous fossil fakes from China in the last few years, most of which came to light through fossil dealers, as did A. xui, and one commentator in the Science article noted that scientists need to “take a skeptical look at this specimen.” He stated that the fact that it is so complete and so “so neatly arranged” raises suspicions that needed to be put to rest before the specimen is completely accepted.