Sauropods of 2008: Dongyangosaurus
January 19, 2009
So, 2008 has come and gone. Was it a good year for sauropods? In terms of new taxa, it wasn’t amazing, but it wasn’t too bad, and (as we’ll see in this and a few following posts) some of the taxa involved had pretty interesting vertebrae. For the record, the taxa named in 2008 were Dongyangosaurus sinensis Lü et al., 2008, Eomamenchisaurus yuanmouensis Lü et al., 2008, Qingxiusaurus youjiangensis Mo et al., 2008, Muyelensaurus pecheni Calvo et al., 2008 (labelled 2007, but actually 2008), Uberabatitan riberoi Salgado & Carvalho, 2008 (previously covered here on SV-POW!), Dixiatitan binglingi You et al., 2008, Pitekunsaurus macayai Filippi & Garrido, 2008, Tastavinsaurus sanzi Canudo et al., 2008 (previously mentioned here), and Malarguesaurus florenciae González Riga et al., 2008 (labelled 2009, but actually 2008). Hold on – that’s 9 new taxa. Wow. I’m not going to look at these taxa in any particular order, nor will I be covering all of them (and if there are any I’ve missed, please let us know).
We start with one of my favourites: Dongyangosaurus from the Fangyan Formation of Dongyang, Zheijiang Province, China. A (probable) non-titanosaurian titanosauriform, its partial skeleton includes beautifully preserved vertebrae (Lü et al. 2008).
The dorsals [shown here, Plate I from Lü et al. (2008)] are neat. The neural spines are described as bifurcate, which I assume means that they are V-shaped at their apices as they are in, say, Camarasaurus or Opisthocoelicaudia: unfortunately this is neither clearly described nor figured in the paper. Prominent spinodiapophyseal laminae (spdls) extend obliquely up the sides of the neural spines, but what’s really odd is that there are deep hollows dorsal and/or posterodorsal to the spdls: these hollows house small subsidiary laminae. The presence of these ‘hollows with subsidiary laminae’ is unique to Dongyangosaurus. At least some of the dorsals also possess – in addition to anterior and posterior centroparapophyseal laminae and paradiapophyseal laminae – subsidiary laminae ventral to the diapophysis and posterior to the parapophysis.
What’s the deal here? Are those cavities on the sides of the neural spines pneumatic? We’d need detailed information on the bone texture here to test this hypothesis. And why all the extra little laminae? Given that laminae seem to help partition air sacs, the presence of small subsidiary laminae hint at the possibility that Dongyangosaurus went nuts (in pneumatic terms), growing lots of extra pneumatic structures in and around the neural arch.
The two preserved caudal vertebrae [shown below, Plate II from Lü et al. (2008)] also reveal some interesting strangeness. The caudal centra are taller than they are wide, and are amphicoelous (concave at both ends). The bases of the postzygapophyses (in an area bound anteriorly by the spinodiapophyseal lamina and ventrally by the postzygodiapophyseal lamina) are perforated by three small fossae, all of which presumably invade the base (at least) of the postzygapophysis. Again, this is unique and used as a diagnostic character for the taxon.
And – that’s it. Another one next time.
Lü, J., Azuma, Y., Chen, R., Zheng, W. & Jin, X. 2008. A new titanosauriform sauropod from the Early Late Cretaceous of Dongyang, Zhejiang Province. Acta Geologica Sinica 82, 225-235.