(This is a brief post. I am still working on other projects, and new stuff that interests me keeps coming out!)
Eventually, a review topic will have to be done to work on these guys. There are now quite a lot of them. The southern Chinese deposits of the Late Cretaceous are turning out a diverse fauna including many small oviraptorids. Asia is getting crowded:
The latest is Nankangia jiangxiensis, described by Lü Junchang and colleagues just this week, which as Matt Martynuick observed on Facebook, brings the Ganzhou oviraptorid naming convention full circle:
Jiangxisaurus ganzhouensis -> Ganzhousaurus nankangensis -> Nankangia jiangxiensis.
(This merely points to the difficulty that will eventually arise when you run out of areas from which to draw names from, and the well of inventiveness that runs dry when doing so. Naming your taxa after characteristics, however potentially exhaustible, at least allows a more intuitive link between name and taxon.)
As of this week, there are now 26 different named oviraptorosaurs from Asia. There are more as yet unnamed and/or undescribed potential varieties. This is making the assumption that Caudipteryx dongi is a synonym of zoui. Eventually, there will be more. Many new discoveries are occurring not in the prolific Gobi Desert, but in the southern Chinese provinces, and these represent a potential deep well of investigation. Many similarities exist between the southern and northern Asian formations of the Coniancian-early Maastrichtian, rather unlike the distinct provincialism of southern and northern Laramidia in North America, in which distinct and non-overlapping faunas co-existed. The “ingeniines” of southern China are remarkably similar to those of Mongolia, as are the apparent inclusion of giant therizinosauroids (Nanshiungosaurus brevispinus) and tyrannosauroids (Tarbosaurus bataar), but also the presence of hadrosaurs (Microhadrosaurus nanshiungensis). The Nanxiong (Yuanpu) and Dalangshan Formations are roughly coeval, and seemingly produced from similar environments conducive to preserving small dinosaurs with intact skeletons and decent preservation. It thus becomes a matter of time as investigations continue in these areas for the fauna to become more fleshed out. However, the sites of recovery have received problematic attention: Quarrying for building materials has destroyed much of what has been discovered, leaving only partial what was once far more complete.
Nankangia jiangxiensis is yet another new, but incompletely preserved, oviraptorid; and like many of the Ganzhou oviraptorosaurs it tantalizes rather than reveals much about oviraptorid evolution.
Problematically, much as I discussed on this series of posts on Wulatelong gobiensis, basal oviraptorid evolution is murky. There’s much we don’t know because many of the taxa are relatively undescribed. Anything that isn’t an “ingeniine,” it seems, is a hodge-podge of basal oviraptorid and it’s not clear what resolution can be had. In as many phylogenetic analyses as there have been taxa described in the last year alone, the distribution of taxa shifts. This latest analysis did not include Wulatelong gobiensis or even other southern Chinese oviraptorids — probably due to their newness, as many of these taxa had not been described by the time of submission or perhaps when the analysis was finalized — in its composition aside from Yulong mini, and as that is a juvenile and may have undue influence on phylogenetic analysis (Carr, 1999; Steyer, 2000; Weins et al., 2005; and pretty much anything by Christian Klingenberg) it leaves one unsatisfied with the results. Testing the composition of Oviraptoridae requires more extensive analysis and greater inclusion of characters relating to the development of the oviraptorid mandible (as the skull remains problematically and poorly described among most oviraptorids). And this is to say nothing of whether some of these Nanxiong/Dalangshan taxa are potential synonyms of one another, even when material is shared (most taxa preserve some portion of the jaw and ilium which allows direct comparison, but see comments about ontogeny above).
I cannot help be intrigued and yet worried over the recent proliferation of taxa, but it is eventually all to the good: More specimens means more robust results and options for paleobiogeographic analysis and phylogeny.
Carr, T. D. 1999. Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19 (4): 497-520.
Lü J.-c., Yi L.-p., Zhong H. & Wei X.-f. 2013. A new oviraptorosaur (Dinosauria: Oviraptorosauria) from the Late Cretaceous of Southern China and its paleoecological implications. PLoS ONE 8 (11): e80557.
Steyer, J.-S. 2000. Ontogeny and phylogent in temnospondyls: A new method of analysis. Zoological Journal of the Linnaean Society 130: 449-467.
Weins, J. J., Bonett, R. M., Chippindale, P. T. & Anderson, F. 2005. Ontogeny discombobulates phylogeny: Paedomorphosis and higher-level salamander relationships. Systematic Biology 54 (1): 91-110.