Archaeopteryx knocked off its perch as first bird

FOR 150 years Archaeopteryx has been iconic as the earliest bird. 

The fossil sports feathered wings but a dinosaur's teeth and tail. Now the discovery of a feathered dinosaur in China has prompted a reassessment that has left Archaeopteryx squarely in dinosaur territory.

The diminutive new fossil, Xiaotingia zhengi, recently acquired by the Shandong Tianyu Museum of Nature from a fossil dealer, was excavated from 160-million-year-old rocks in Liaoning province (see the fossil here). 

It shares several key anatomical features with Archaeopteryx, including a "killing claw" on its second toe, and long and robust arms that probably allowed it to glide.

However, a team led by Xing Xu at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing deemed it sufficiently distinct from birds to be classified as a theropod dinosaur known as a deinonychosaur - and because of the similarities with Archaeopteryx, Xu's team concluded that the "first bird" is a deinonychosaur too (Nature, DOI: 10.1038/nature10288).

"We used to think Archaeopteryx was so different from other dinosaurs that it was ancestral to birds, but recent discoveries show that this is no longer the case," says Xu. "Our main conclusion is that Archaeopteryx is no longer a bird."

Other palaeontologists give Xu's findings a cautious welcome. "I am not surprised," says Gareth Dyke of University College Dublin in Ireland. "Flight may have evolved many times among small bodied theropod dinosaurs."

If Xu's analysis holds up it will create quite a headache for taxonomists as Archaeopteryx is used to define the base of the birds. 

One solution would be to include deinonychosaurs in the birds, says Luis Chiappe of the Natural History Museum of Los Angeles County, California.

Hunting For Fossils On Jupiter's Europa

Hunting For Fossils On Europa

If extraterrestrial life exists on Jupiter's moon Europa, instead of deploying probes to drill past its ice shell to look for aliens in the ocean below, one might just go fossil-hunting on the icy surface.

"A prospector sent there could possibly find extraterrestrial life within our lifetimes," suggested planetary scientist Richard Greenberg at the University of Arizona's Lunar and Planetary Laboratory at Tucson.

Europa, which is roughly the size of Earth's moon, is enveloped by a global ocean that may be about 100 miles deep (160 km). This ocean is overlain by an icy crust of unknown thickness, although some estimates are that it could be only a few miles thick.

Since wherever there is water on Earth there is a chance of life, for many years scientists have entertained the notion that this Jovian moon could support extraterrestrials. Recent findings even suggest its ocean could be loaded with oxygen, enough to support millions of tons worth of marine life like the type that exists on Earth.

To see if any kind of life actually evolved on Europa, scientists have proposed missions to drill through its outer shell, perhaps using heat to melt through the ice, whirring blades to clear away rocks and robot subs to explore the ocean.

"With that vision in mind, NASA has a multi-staged plan, first with a Europa orbiter scheduled for 18 years from now, and 10 or 20 years after that, a lander to see what the surface is like, and then maybe a generation later, hopefully we can figure out how to drill all the way down through the ice," Greenberg noted.

He recently wrote a book, "Unmasking Europa," which touched upon how one might search for life on the Jovian moon.

Labrador Retriever-Sized Herbivore Shakes up Theories of Dino Evolution

Labrador Retriever-Sized Herbivore Shakes up Theories of Dino Evolution

In this week’s Nature, researchers say they’ve analysed a near-complete skeleton of one of the closest relatives to early dinosaurs, a silesaur called Asilisaurus.

The fossil is more than 240 million years old, which is ten million years older than the earliest known fossils of true dinosaurs.

The finding of this dino relative therefore suggests that dinosaurs emerged earlier than we previously believed, and it throws another surprise into the debate over their origins.

From the remains of 14 different individuals, the scientists managed to piece together what a whole skeleton looked like.

However, the finished product didn’t look quite like they expected. After studying the bones for 3 years, the team concludes that Asilisaurus was about the size of a Labrador retriever.

The animal walked on four legs, and the shape of its teeth suggests that it ate plants and maybe a little meat.

That conflicted with the expectation of the study's co-author Randy Irmis, who said the team would’ve thought small carnivores, and not mostly plant eaters walking on four legs, were the closest relatives to the dinosaurs.

Indeed, that question remains open. According to the Nature editor’s summary, Asilisaurus is an early member of the Ornithodira line, the “avian” group that broke off from the crocodile group during the time before dinosaur emergence.

What does that mean for the dinosaur ancestry? The balance of opinion has alternated between more reptilian ancestors, which walked on all fours, and two-legged animals that had bird-shaped bodies but couldn’t fly.

Recently, the idea of two-legged dino ancestors had been winning out, but the new find draws the trend back toward quadrupeds.

Paul Barrett of London’s Natural History Museum says: “The creatures share a lot of features with dinosaurs,” he said. “They show us an intermediate step between more primitive reptiles and the more specialised dinosaurs”.

While dinos hung around for 165 million years or so, the Silesaurs like Asilisaurus lived only 45 million years before extinction.

However, since Ssilesaurs and true dinosaurs diverged from a common ancestor, the two groups should have existed during the same time frame.

Thus, the earliest emerging dinos might stretch back even to the time frame of this Asilisaurus, more than 240 million years ago.

Hundreds of Insect Fossils found in Amber