On digits and diets.

19 06 2009

Good tidings and well-wishes, ladies and gentlemen!

The recent discovery of a new and very unique ceratosaur Limusaurus inextricabilis has ignited a firestorm of articles and posts from the paleontological community. What’s so special about it?

For starters, as Dave Hone writes, it probably had strong herbivorous tendencies. 

Perhaps more important, however, is its implications for the evolution of theropod and avian digits. The famed PZ Myers, author of the ever-popular (and controversial) “Pharyngula”, wrote an excellent post explaining the alterations of genetic mechanisms which assign digit identity during the evolution of birds back in 2002. The discovery of this animal has turned the evolutionary biologist’s statements into fulfilled prophecy, as he explains here.  

To quote Jeff Martz, “Gee, it’s almost like that evolution stuff really works…”

May the fossil record continue to enchant us all!




3 responses

22 06 2009
Zach Miller

Like I’ve said elsewhere, I remain unconvinced that Limusaurus’ hand actually has anything to do with frame shifting in the theropod manus. Ceratosaurs in general have short arms with stumpy fingers–even Ceratosaurus. It gets so bad that in carnotaurine abelisaurs (like Carnotaurus and Aucasaurus), the arms are vestigal structures that may have been functionless.

Considering Limusaurus’ host of derived features, I think the best explaination for the stumpy hands is an aupomorphy OR an extreme development of a family-wide trend.

24 06 2009

Perhaps you’re right…I myself remain prohibitively ill-versed in the finer aspects of theropod digit morphology and therefore cannot provide an intelligent response to your comments.

Maybe, if we’re to find irrefutable proof of a frame-shift, specialists ought to look towards more basal theropods…

24 06 2009
Zach Miller

Or more advanced ones. I believe there are a few megalosaurs (higher than ceratosaurs) with four fingers, so I’m betting the frame-shift occurred somewhere near the base of Tetanurines.

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