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New Nemegtosaurus paper

Wilson, J.A. (2005). Redescription of the Mongolian sauropod _Nemegtosaurus mongoliensis_ Nowinski (Dinosauria: Saurischia) and comments on Late Cretaceous sauropod diversity. Journal of Systematic Palaeontology 3: 283-318.

Abstract: "The isolated skulls of _Nemegtosaurus mongoliensis_ and _Quaesitosaurus orientalis from the Nemegt Basin of Mongolia are among the most complete sauropod cranial remains known from the Late Cretaceous, yet their evolutionary relationships to other neosauropods have remained
uncertain. Redescription of the skull of _Nemegtosaurus_ identifies key features that link it and its closely related counterpart _Quaesitosaurus_ to titanosaur sauropods. These include a posterolaterally orientated quadrate fossa, `rocker'-like palatobasal contact, pterygoid with reduced quadrate flange and a novel basisphenoid?quadrate contact. Other features are exclusive to
_Nemegtosaurus_ and _Quaesitosaurus_, such as the presence of a symphyseal eminence on the external aspect of the premaxillae, a highly vascularised tooth bearing portion of the maxilla, an enclosed `maxillary canal', orbital ornamentation on the postorbital, prefrontal and frontal, exclusion of the squamosal from the supratemporal fenestra and dentary teeth smaller in diameter than premaxillary and maxillary teeth.
"Re-examination of Late Cretaceous sauropod distributions in the light of this well-supported phylogenetic hypothesis has important implications for their diversity at the end of the Mesozoic in Asia and elsewhere. Cretaceous Asian sauropod faunas consist solely of titanosauriforms, which probably migrated there from other landmasses during the Late Jurassic, during which time neosauropods were absent from Asia. Globally, narrow-crowned titanosaurs and rebbachisaurids radiated during the Cretaceous, but only titanosaurs survived into the latest Cretaceous. These late-surviving sauropods flourished on most continental landmasses until the end of the Maastrichtian."

Wilson (2005) re-defines the Nemegtosauridae as the stem-based clade including all titanosaurs more closely related to _Nemegtosaurus_ than to _Saltasaurus_. This group includes (at least): _Nemegtosaurus_, _Quaesitosaurus_, _Rapetosaurus_, possibly _Mongolosaurus_ (which is regarded as a valid genus) and maybe even _Phuwiangosaurus_ (although the postcranium indicates that it was a more basal titanosaur). _Quaesitosaurus_ is not considered a junior synonym of _Nemegtosaurus_, though the two are sister taxa. _Antarctosaurus wichmannianus_ may also be a nemegtosaurid; but Wilson is not certain that all the material referred by Huene to _A. wichmannianus_ comes from a single individual or species.

Like many previous authors, Wilson also raises the possibility that _Nemegtosaurus_ and _Opisthocoelicaudia_ may be the same; but overlapping material is required before this can be considered. Considering that Nemegtosauridae and Opisthocoelicaudiinae have both received phylogenetic definitions, such a synonymy would raise interesting nomenclatural issues...

Wilson (2004) also notes that titanosaurs and rebbachisaurids appear to be the only two sauropod clades that flourished in the Cretaceous. Although other groups (brachiosaurids, dicraeosaurids, basal diplodocoids) survived into the Cretaceous "they did not appear to diversify".