[N] 2009 First diplodocid from Asia
Upchurch, P. & Mannion, P.D. (2009) The first diplodocid from Asia and its implications for the evolutionary history of sauropod dinosaurs. Palaeontology Vol 52 Part 6 pp. 1195-1207
An isolated anterior caudal vertebra from the Qingshan (= Ch’ing shan) Formation [Qingshan Formation] (Early Cretaceous) of Shandong Province, China, is redescribed and shown to be an advanced diplodocid sauropod. This specimen possesses several derived character states that are typically observed in advanced diplodocoids or diplodocids, [Diplodocidae] including the following: a mildly procoelous centrum; a deep pit-like pneumatic fossa immediately below the caudal rib; wing- or fan-shaped caudal ribs; and complex lamination of the neural spine. The neural spine is apomorphically short and the centrum is short relative to its height compared to those of other diplodocids, which, when coupled with the specimen’s unique geographical location and stratigraphical age, suggests that it probably represents a new taxon. This caudal vertebra provides the first convincing evidence that diplodocids were present in Asia, perhaps as a result of the dispersal of neosauropod lineages from Europe and ⁄ or North America during the Early Cretaceous. The discovery of a member of the Diplodocidae in the Early Cretaceous also indicates that this clade did not become extinct at the Jurassic ⁄ Cretaceous boundary as previously supposed.
Nemegtosaurus mongoliensis - Nemegt Formation
Phuwiangosaurus sirindhornae - Sao Khua Formation
Quaesitosaurus orientalis - Barun Goyot Formation
The occurrence of diplodocoids in Asia is more problematic. Several phylogenetic analyses have placed the Late Cretaceous Mongolian nemegtosaurids Nemegtosaurus and Quaesitosaurus within Diplodocoidea (e.g. Yu 1993; Upchurch 1995, 1998, 1999; Upchurch et al. 2004a), but there is now substantial evidence that these forms are actually members of the Titanosauria (Salgado and Calvo 1997; Wilson and Sereno 1998; Curry Rogers and Forster 2001; Wilson 2002, 2005; Curry Rogers 2005). Another putative Asian diplodocoid was identified by Hasegawa et al. (1991), based on a partial humerus from the Miyako Group (late Aptian – early Albian) of Iwate Prefecture, northern Honshu, Japan. This interpretation was based on the overall similarity of the humerus to those in mamenchisaurid sauropods, which, at the time, were considered to be an aberrant subfamily of the Diplodocidae (McIntosh 1990). However, the accuracy of this identification is doubtful for two reasons. First, Mamenchisaurus and its close relatives have been shown to be basal eusauropods, not diplodocoids, by all phylogenetic analyses based on extensive datasets (e.g. Upchurch 1995, 1998; Wilson 2002; Upchurch et al. 2004a; Harris 2006). Second, the Japanese humerus bears no derived character states that uniquely link it to the Diplodocoidea or any of its constituent taxa (Barrett et al. 2002). Consequently, we agree with Azuma and Tomida (1998) and Barrett et al. (2002) that this Japanese specimen should be regarded as Sauropoda indet. (Upchurch, P. & Mannion, P.D. 2009)