These are all quite impressive. I am embarking on a project, illustrating all of the Nemegt Formation dinosaurs, and your oviraptorsaur skeletals are a treasure trove and a relief... I was dreading having to wing it and risk severe anatomical inconsistencies with my restorations. But concerning the Opisthocoelicaudia... Is it indeed distinct from Nemegtosaurus? The fact that we have a skull and a postcranial skeleton known from the same formation and they're classified as unique genera? It seems a bit off to me.
So far, the reasoning for it being distinct is based on the presence of a distinct skeletal type known for nemegtosaur-like skulls in Rapetosaurus krausei, from Late Cretaceous Madagascar. Morphological differences abound between the two types of postcranial skeletals, making it more difficult to assume the skull of Nemegtosaurus mongoliensis and the body of Opisthocoelicaudia skarzynskii come from the same animal.