Nullary Sources

Ed Yong of Discover Magazine’s Not Exactly Rocket Science blog:

The eleven specimens of Archaeopteryx are some of the most iconic and captivating fossils in existence. The fingers end in claws, the tail is long and bony, and the head – arched back in the throes of death – contains toothed jaws. But the splayed arms are lined with the faint but unmistakeable outlines of feathers. This was an animal halfway between a small flesh-eating dinosaur and a modern bird. In fact, Archaeopteryx is widely heralded as the first bird, occupying a pivotal position in the origins of this group.

But Xing Xu from Linyi University thinks that this first bird was nothing of the sort. The Chinese palaeontologist, who has found one fascinating dinosaur after another, has identified a new species called Xiaotingia that threatens to oust Archaeopteryx from its position.

By comparing Xiaotingia’s features with those of Archaeopteryx and other related birds and dinosaurs, Xu has drawn up a new family tree. In it, Archaeopteryx sits with Xiaotingia among the deinonychosaurs, a celebrity-filled group of small, predatory dinosaurs that includes Deinonychus and Velociraptor. The lineage that led to modern birds perches on a different branch of the tree.

This doesn’t change the fact that birds evolved from dinosaurs – it merely relegates Archaeopteryx to the sidelines of that process. In its place, species like Epidexipteryx and Epidendrosaurus take up the mantle of earliest birds. It is a tentative revision but a bold one (Xu himself admits that the new family tree is statistically weak). …

Meanwhile, others have noted that Archaeopteryx has many features that are only found among the deinonychosaurs. For example, they share a distinctive hip bone, and they both have a large hole above their noses (the “premaxillary fenestra”) that other birds and dinosaurs lack. Any many of the features that supposedly characterise Archaeopteryx and other birds, such as feathers, a wishbone and long powerful forearms, are also found in deinonychosaurs.

…

But Gerald Mayr, who studies fossil birds at Germany’s Sneckenburg Museum, is unimpressed with the new discovery. “I fear that it is a bit hyped and that the conclusions are not as novel as the authors claim,” he says. Mayr is one of several palaeontologists who think that the deinonychosaurs are actually birds themselves. According to him, they’re flightless members of a group that includes Archaeopteryx and modern birds, like smaller extinct versions of today’s ostriches and emus.

The problem is that all of these reconstructions are weak. Mayr admitted as much about his own model back in 2006, and Xu says that his new family tree only has “tentative statistical support”.

‘Ili:

EVERYTHING I KNOW IS A LIE

Colin:

At least birds are still dinosaurs.

Colin:

THAT’S WHAT’S IMPORTANT