Wednesday, June 17, 2009

Two Awesome Dinosaur Stories

Two new papers, hot off the virtual presses.

Xing Xu et al, “A Jurassic ceratosaur from China helps clarify avian digital homologies,” Nature 459:940 doi:10.1038/nature08124

Look, ma: no teeth! I remember seeing the presentation for this beastie (Limusaurus) at SVP last year and was very excited about it. You could almost call it the ceratosaur version of an alvarezsaur. It's got long legs, short little arms, a lengthy neck and toothless jaws (and, one would assume, a beak). That's cool enough, right? Well, even better, Limusaurus helps solve the riddle of why non-avian theropods retain digits I-III, but modern birds seem to have digits II-IV. BAND members have pointed to this inconsistency time and time again to invalidate a theropod origin for birds (like any of their "ancestors" have digits II-IV). Limusaurus may solve the problem, as it retains digits I-IV, but digit I is reduced to a single stumpy phalange. The authors suggest that this represents a transition, and that what we see as digits I-III in tetanurine theropods is actually digits II-IV, and that those digits have taken on the characteristics of digits I-III. I don't know how convinced I am of this--Limusaurus is ridiculously derived AS IS. Either way, it's an awesome theropod regardless of what its finger formula implicates.

Paul C. Sereno, Zhao Xijin, and Tan Lin
A new psittacosaur from Inner Mongolia and the parrot-like structure and function of the psittacosaur skull
Proc. R. Soc. B published online before print June 17, 2009, doi:10.1098/rspb.2009.0691

Parrots crack nuts with their big curved beaks, and that's exactly what Sereno, Xijin & Lin are suggesting psittacosaurs did in this new paper. I'm not sure if they're describing another new species within the genus or simply a new well-preserved skull. National Geographic has a brief story about it, and if that's the skull they found, it's a nice-looking skull.

Thanks to Nick Gardner for sending me both papers. I'll have a tongue-in-cheek blog up about Limusaurus in the next few days.

3 comments:

Julia said...

Okay, the Nature article isn't actually up online yet, but if you ask Dave Hone (or any other tame authors on the paper) nicely he might have a PDF. It should be up by tomorrow morning though, so if I have access I'll send it on.

I definitely don't have Proceedings B access though. Jerry might send it through at some point.

Nick Gardner said...

I linked to your post.

See: Acta Palaeontologica Polonica now available online back to 1980 by Nick Gardner, 06192009

Nick Gardner said...
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