After analysing the traits present in Xiaotingia and its relations, Xu and his colleagues are suggesting that the creatures bear more resemblance to the dinosaurs Velociraptor and Microraptor than to early birds, and so belong in the dinosaur group Deinonychosauria rather than in the bird group, Avialae. Many features led the team to this decision, but the most immediately noticeable are that Xiaotingia, Archaeopteryx and Anchiornis have shallow snouts and expanded regions behind their eye sockets. Microraptor has similar traits, but the early birds in Avialae have very different skulls.
But what if they find a fossil that looks like those ones, but has a bird-like skull? Can they say why they are sure they won’t? Is that a prediction?
The first Archaeopteryx specimen was discovered in 1861, just a few years after the publication of Charles Darwin’s On the Origin of Species. Its combination of lizard-like and avian features made it the ideal ‘missing link’ with which to demonstrate evolution from non-avian dinosaurs to birds. But the latest rearrangement knocks it from its position as the earliest bird. “I think Archaeopteryx ‘s placement was the result of both history and relatively poor sampling at the dinosaur–bird transition,” explains Xu.
Translation: The classification was embraced for ideological, not science reasons.
Even so, he acknowledges that the move is bold. “Because it has held the position as the most primitive bird for such a long time, I am kind of nervous about presenting this result,” says Xu. But immediate responses from others in the field suggest that the decision will be widely embraced.
Mmmm. People have lost their jobs for less. Depends, really, on how fast new Darwinfacts can be manufactured for the museum docents, like here.