Mongolosaurus haplodon, Gilmore, 1933

D, Michael D. & Emic, 2012, The early evolution of titanosauriform sauropod dinosaurs, Zoological Journal of the Linnean Society 166 (3), pp. 624-671 : 649

MONGOLOSAURUS HAPLODON ( GILMORE, 1933)

Mongolosaurus was collected from the Early Cretaceous of China and is based on fragmentary teeth, part of a basicranium, and three vertebrae. Wilson (2005) and Mannion (2011) established the validity of Mongolosaurus on the basis of several features, and both studies suggested that it was a titanosaur. In contrast, as noted by Wilson & Upchurch (2009), Mongolosaurus shares some features with Erketu , a Cretaceous East Asian sauropod outside of Titanosauria: tall, pillar-like epipophyses and an elongate axis with a tall ventral keel. Mongolosaurus possesses bifid neural spines as in all East Asian Cretaceous titanosauriforms (see below). These three features suggest euhelopodid affinities for Mongolosaurus , in contrast to the 11 features suggesting titanosaur affinities proposed by Mannion (2011). However, many of the 11 characters proposed by Mannion (2011) deal with parts of the skull that are unknown in almost all euhelopodids, making these comparisons equivocal. Furthermore, some cranial ‘titanosaur’ features proposed by Mannion (2011) have a broader distribution amongst sauropods. For example, mesial and distal tooth carinae and D- shaped cross-sections are features of the teeth of the non-titanosaur Phuwiangosaurus (pers. observ.), and variability in tooth shape between upper and lower jaws is also present in the brachiosaurid Abydosaurus ( Chure et al., 2010) . In sum, Mongolosaurus displays a mix of features that suggest titanosaur or euhelopodid affinities.