Wednesday, March 18, 2009

Mystery Wednesday Solved... Feathered Ornithischians?

Just when you thought the picture of feather evolution was getting clearer... enter Tianyulong, the feathered heterodontosaurid.


You heard me. Read about the new find at Ed Young's blog.

[Image: Tianyulong confuciusi, credit Li-Da Xing]

So what does it all mean? I doubt there'll be any consensus, but the authors do a pretty good job of showing that, like the feathers of Sinosauropteryx and Beipiaosaurus, these structures are hollow and not collagen. So were all dinosaurs (or ornithodirans as a whole, dinosaurs + pterosaurs) feathered, and many lost feathers and re-grew scales? The distribution is now making it look like all these structures (ceratopsian quills, ptero-fuzz, feather,s protofeathers and now ornithischian fibres) are homologous--that is, they all derive from a common, ancestral structure. However, I think it's more likely that these started out at bristle-like quills, and evolved into softer, more fuzzy pelts in a few lineages independently, the small, active ones that would be pre-disposed to adapting these inherited quills.

But what do I know? I'll keep you posted on what ideas start getting inevitably tossed around.

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