ON ASIAN ORNITHOPODS (DINOSAURIA, ORNITHISCHIA) .2. ARSTANOSAURUS AKKURGANENSIS SHILIN AND SUSLOV, 1982

The hadrosaurid dinosaur Arstanosaurus akkurganensis was described on the basis of the posterior end of a left maxilla, an associated distal end of a femur and an unreported isolated tooth, all of which were co llected from the Akkurgan locality, East of the Aral Sea in central Ka zakhstan. Redescription of the type material reveals that the material was inaccurately described, appears to lack specifically diagnostic c haracters and, although it can be assigned tentatively to the hadrosau rid subfamily Lambeosaurinae on the basis of the form of the caudodors al margin of the maxilla, should for taxonomic purposes be regarded as a nomen dubium. Arstanosaurus cannot be assigned to any known hadrosa urid taxon from Kazakhstan with any confidence at present partly becau se of a lack of comparative material, and difficulties of comparative dating across what appear to be very similar localities (e.g. Shakh-Sh akh). Broad anatomical similarities can be drawn with the Chinese genu s Bactrosaurus. Additional hadrosaurid material collected from Baynshi n Tsav, Mongolia, previously attributed to the genus Arstanosaurus, re presents two new ornithopod taxa assignable to the subfamilies Hadrosa urinae and Lambeosaurinae. General comparison between the forms collec ted from Akkurgan, Iren Nor (China) and Baynshin Tsav supports the con tention that all three localities may be dated as Early Senonian (Coni acian-Santonian) in age.