Friday, October 24, 2008

Look, it's Les!

Nature reported today on a strange new feathered theropod from China. You might recognize this picture from other blogs. Indeed, it's covered elsewhere (Tet. Zoo, Archosaur Musings, HMNH) far better than you can expect here. I don't even have a copy of the paper!

*wink wink nudge nudge*

The new animal, Epidexipterus, is a subadult scansoriopterygian that's a mere 20 cm long--itty bitty to the extreme. As a subadult, I doubt the whole animal would've grown too much more, especially since its ribbon-like caudal display feathers have grown in (implying it's hit sexual maturity). I believe this makes Epidexipterus the smallest known non-avian dinosaur, beating Microraptor and Mei by a large margin. Among the more unique features to the animal: Procumbent dentition in the manner of Masiakasaurus, a surprisingly primitive pelvic arrangement, and very strange feathers that appear tufted but lack a central rachis. Indeed, the paper suggests that the feather filliments arise from some vague "membraneous" structure. Four very long "ribbon-like" feathers originating from the tail, which reminds me of Confuciusornis. The feathers appear very stiff.

Unfortunately, Epidexipterus lacks features (mostly due to incomplete preservation) that might synonymize it with Scansoriopteryx. The fossil does not preserve the hands very well, so that long aye-aye-like third finger is nowhere to be found. Epidexipterus has a mouth full of teeth, unlike its toothless baby cousin, and the tail seems incredibly short, although there's a break between the pelvis and the preserved caudals. While this could mean that a section of the tail was not preserved, the very close association between the back of the pelvis and the preserved caudals says to me that the tail really is very short. Once I somehow get ahold of the description, I plan on doing on my usual B&W line drawing restorations. Look forward to it, kiddies!


Sean Craven said...

Man, I am so curious about what this means in terms of avian and maniraptoran evolution. Since this animal has very primitive feathers and other maniraptorans have flight feathers...

Well, I'm having a hard time wrapping my noggin around the exact meaning of this. Weird, weird, weird. I just wish I had enough education to see a little more deeply into this.

Christopher Taylor said...

Epidexipteryx, not Epidexipterus. The article's in the mail.

Sean: Before feathers got exapted to being used for flight, there would have not necessarily been the same selective pressure to retain "flight-form" feathers, so this creature could have quite easily descended from an ancestor with such feathers. Modern flightless birds show a number of different feather morphologies that aren't found in flighted birds (such as the barbule-less feathers of kiwis and Casuariiformes).

While I haven't looked into it in detail, I get the impression that many feathered maniraptors, such as oviraptorosaurs, might have had downy feathers over most of the body, while planar feathers were restricted to the limbs.

Sean Craven said...

It's moments like this that make me realize I'm nowhere near as rigorous in my thinking as I'd like to be.

For some reason I had it in the back of my head that this was a basal maniraptoran. (sound of hand smacking forehead, followed by plaintive cries of self-recrimination)