Aardonyx, after Yates et al. in press
Dedicated readers of the blog likely remember that one of the core research goals of this project is to examine the bipedal/quadrupedal transition in ornithischian dinosaurs. Of course, ornithischians weren’t the only group to experience such locomotor changes during their evolution! A new paper on the bipedal/quadrupedal transition in sauropodomorphs (the saurischian dinosaur group including animals like Plateosaurus, Apatosaurus, and Brachiosaurus) has just appeared on Proceedings of the Royal Society B‘s FirstCite. This paper, headed up by Adam Yates, details the anatomy of Aardonyx, an early sauropodomorph from the Early Jurassic of South Africa. The authors posit that the new critter was a habitual biped, although it had many features that presaged the anatomy of later quadrupedal forms.
The paper has already been covered in some depth elsewhere in the blogosphere – check out posts by senior author Adam Yates, Dave Hone, Sid Perkins, and Bill Parker for more.
If you haven’t contributed data to the Open Dinosaur Project yet, and are looking for something to do, this might be a good one! The supplementary information (freely available) is chock-full of measurements.
Citation
Yates, A. M., Bonnan, M. F., Neveling, J., Chinsamy, A., and M. G. Blackbeard. In press. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proceedings of the Royal Society B. doi:10.1098/rspb.2009.1440. Published online 10 November 2009. [subscription required for full access]
The Open Dinosaur Project 
In a recent paper Hutchinson also summarized the available methodology and pitfalls on the study of locomotive change in archosaurs, in which he noted that (among other salient points): (1) these studies have been centered on the evolution towards Neornithes, while that in Sauropodomorpha and Ornithischia have been neglected, and (2) quadrupedalism was ancestral for Archosauria.
Thus it may be important to consider why dinosauromorphs / early dinosaurs took to bipedalism (ecological advantages?) and why most lineages besides theropods HAD to revert back to quadrupedalism. In addition, which characters WERE plesiomorphic to quadrupedal archosaurs and which were evolved during this secondary acquisition of quadrupedalism among different lineages of dinosaurs?
See: Hutchinson JR (2006). The evolution of locomotion in archosaurs. C R Palevol 5:519-530.
Excellent points – that’s a paper we’ll probably want to review here on the blog.
The PDF of the Aardonyx paper is freely available for download for seven days from publication, so get it before it goes behind the paywall!
I got it, but hard-copy printing is restricted…
Shouldn’t be – I was able to print it out just fine.