Once Palaeontologists get their heads down to revise classification things start to be seen with different eyes and everything changes. There’s almost a full acceptance now on the newest reclassification of dinosaurs, that managed to challenge the traditional dinosaur evolutionary tree… we were used to see Dinosaurs as “Ornithischians” and “Saurischians”. No more: we have now Saurischia (subdivided in Herrerasauridae and Sauropodomorpha) and Ornithoscelida (subdivided in Theropoda and Ornithischia) ,
But, just as in Darwin times, we needed a “Missing Link”… South America continues to produce wonders! Meet Chilesaurus diegosuarezi, the latest motive of confusion on one side and settling an argument on the other. This new dog-sized animal has been called the “Frankenstein” dinosaur. For the late Jurassic, it must have been already a relic! In parts it looked like a theropod with the backwards pelvis of an Ornithischian. The dentition showed also a vegetarian diet. The mixture of characters made it anomalous from the moment it was discoveredend (even the pelvis looks primitive for an ornithischian!), but it is only until now that finally everything makes sense: it is a basal ornithischian with theropod characteristics! Yes it seems that this is the Missing Link the new Ornithoscelida grouping was calling for! Ornithischia and Theropoda are confirmed more closely related than it was previously thought, thanks to this new primitive Ornithischian with major Theropodan characteristics… The strong, two clawed hands (with vestigial third finger) look very theropod-like, and the pelvic differences that defined both clades are now better understood thanks to the transitional stage of Chilesaurus,
And where did the old Saurischia go? Well, Sauricschia now comprises Sauropodomorpha and Herrerasauridae. So the dinosaur family tree just got more… complicated. 
I am currently updating to the last detail the forthcoming new opening of Dinosaur rEvolution in several places in Australia… and I’m betting we are going to be the first ones to have a completely update, revolutionary view of dinosaur evolution. In the meantime, this little critter is going to be prominently featured!
Of course, the external porcupine-like external integument is my own personal prediction…
Chilesaurus is a fascinating beastie. But this proposed basal ornithischian relationship for Chilesaurus may not be the last word re its relationships. The recent analysis that recovered this position (Chilesaurus-as-basal-ornithschian) omitted tetanuran theropods – the original position for Chilesaurus.
P.S. Great artwork!
Polemical indeed… we shall await more papers on the subject and things may change drastically. In the meantime, “Frankenstein” is a wonder. I have even thought that it might explain things even like therizinosaurs!
I’d say that therizinosaurs are firmly entrenched among the coelurosaurs, as derived theropods.
A paper with five authors is in the works. Stay tuned. 🙂
Well, yes. They’re not leaving that place.