Classification Huabeisaurus

alternate view of mount

the original description of species noted strong similarities between osteology of huabeisaurus , other cretaceous east asian sauropods, , in general, previous studies have pointed east asian cretaceous sauropod (like nemegtosaurus , phuwiangosaurus) sister taxon of huabeisaurus. since 2000, year of original description of huabeisaurus, 17 new sauropod species have been erected cretaceous of east asia. many authors have noted similarities among cretaceous east asian sauropods, suggesting several of these taxa belong clade grounded on genus well-known anatomy (like nemegtosauridae, opisthocoelicaudinae, , euhelopodidae). cladistic support presented euhelopodidae consisted of exclusively cretaceous-aged members, in contrast traditional studies , cladistic analyses placed existence of euhelopodidae jurassic forms. both earlier , later analyses suggest degree of endemism in east asia, though temporal duration remains uncertain. on broader scale, interesting evolutionary pattern has been recognized wherein pre-cretaceous jurassic asian sauropods lie outside of neosauropoda, whereas cretaceous asian sauropods titanosauriforms. refining , explaining these paleobiogeographic patterns through time rests on detailed comparisons , comprehensive phylogenetic studies including east asian sauropods, lacking.

femur

huabeisaurus has never been incorporated cladistic analysis, several authors have commented on affinities on comparative grounds. buffetaut et al. reviewed sauropods of thailand , described late jurassic , cretaceous teeth similar of euhelopodids (in traditional sense, i.e., euhelopus, mamenchisaurus , omeisaurus) , others more reminiscent of nemegtosaurus , phuwiangosaurus (which termed nemegtosaurids). following these comparisons, huabeisaurus regarded nemegtosaurid buffetaut et al.. upchurch et al. considered huabeisaurus represent titanosauriform or titanosaur outside of lithostrotia on basis of variety of features. et al. suggested close relationship between huabeisaurus, borealosaurus, , opisthocoelicaudia. mo et al. highlighted similarities among huabeisaurus, fusuisaurus, , sonidosaurus. tanimoto et al. considered huabeisaurus closely related nemegtosaurus, borealosaurus , “toba sauropod” of japan (as members of nemegtosauridae). finally, has been suggested d emic et al. huabeisaurus member of euhelopodidae.

a new family erected place huabeisaurus in, along closely related tangvayosaurus. family named huabeisauridae. recently, family again proposed, time d emic et al. because euhelopodidae, huabeisaurus has been assigned recently, might have split smaller clades throughout somphospondyli because of taxa assigned it.

pang , cheng tentatively suggested titanosaurus falloti referred huabeisaurus. however, t. falloti represented femoral remains, , femur bears no uniquely shared features huabeisaurus. furthermore, femora of huabeisaurus , t. falloti differ in bevel of distal end versus long axis of bone, 2 cannot represent same genus.

distinguishing characteristics

dorsal vertebra

according d emic et al. (2013) huabeisaurus can distinguished based on set of autapomorphies: division of presacral vertebral laminae; posterior cervical vertebrae divided prezygodiapophyseal lamina; anterior dorsal vertebrae divided anterior spinodiapophyseal lamina; presence of postzygapophyseal spinodiapophyseal fossa larger postzygapophyseal centrodiapophyseal fossa on anterior-middle caudal vertebrae; caudal vertebrae small caudal ribs disappear around caudal vertebra eight; ventrally one-third of anterior-middle caudal vertebral centra expanded posteriorly; 2 longitudinal ridges on lateral faces of mid-caudal vertebral centra; coracoid tubercle near anterodorsal edge of lateral face; distal end of radius twice broad transversely midshaft (convergently acquired in derived titanosaurs); tubercle on ischial plate projects posterior margin; development of fossae relative 1 in caudal vertebral neural arches; , high tibia-to-femur ratio.