The best guess as to why this area in China contains so many well preserved fossils boils down to how quickly the remains were covered in volcanic ash.
"Xu has had a bounty of fossils to work on, particularly from Liaoning. The creatures unearthed there are remarkably well preserved, perhaps because they were entombed quickly during volcanic eruptions and mudslides between 160 million and 120 million years ago. The rocks record fine details including the imprints of feathers, which allowed Xu to determine that a fierce 9-metre-long tyrannosaurid, which he named Yutyrannus, had a coat of long feathers"
"Fossils of big animals are rare—and fossils of small organisms are rarer still, because small, delicate bodies decompose more readily than larger ones. However, in Liaoning even small animals and insects were well preserved.
This is because when plants and animals died there, they often washed into one of the many streams and lakes in the region. More importantly, they were quickly covered in volcanic ash soon after death. Because the remains were buried so rapidly, many of the Liaoning fossils preserve much of the entire organism in remarkable detail."
I know it doesn't fit the profile (a lion's body and hind legs), but when I first saw the picture, I immediately thought "that's a griffin". The fact that there were also feathers on the hind legs and tail-feathers instead of a lion's tail were only things I noticed after looking more closely!
Wow, that article linked to this[1], from which I learned that the largest flying Pterosaurs had wingspans of over 10m (~35ft), and weighed upwards of 250kg (550lb).
So fantasy dragons and Avatar notwithstanding, six limbs on a land dweller is pretty weird. I'm going to have to question this creature either being real or actually having four-wings and a pair of legs.
edit Looking a bit more into it, it looks like the artist's picture is a hopeful fantasy. The class of animals were more like flying squirrels in the sense that they used their hind legs for lift as well. So they're four limbed animals.
Dinosaurs are part of the tetrapod clade, so I never expected "four-winged" to mean anything other than that the hind limbs and forelimbs are both feathered and used for flight. That's what the artist's conception based on the discovered fossils shows.
Oh wow. I think I need more coffee. The first few times I looked at the artist's rendering, I swear I thought it was a 4 winged, two legged animal. But you're right, they rendered it as a tetrapod.
The drawing is very confusing. It looks as if the back wings are just obscuring clawed legs rather than being the legs themselves. I had exactly the same thought as you and came here to comment the same thing.
http://img.washingtonpost.com/news/morning-mix/wp-content/up...