▁a ▁genus ▁of ▁sau rop od ▁din osa ur ▁known ▁from ▁teeth ▁found ▁in ▁Asia . ▁Two ▁species ▁have ▁been ▁named ▁for ▁this ▁obsc ure ▁genus . ▁It ▁was ▁originally ▁named ▁as ▁Chi ay ü sa urus , ▁but ▁the ▁IC Z N ▁does ▁not ▁permit ▁special ▁characters , ▁so ▁it ▁has ▁become ▁Chi ay us aur us . ▁The ▁old ▁name ▁can ▁still ▁be ▁seen ▁in ▁older ▁sources , ▁though . ▁ ▁History ▁and ▁tax onomy ▁Bir ger ▁Boh lin ▁based ▁Chi ay us aur us ▁on ▁a ▁to oth ▁crown ▁in ▁the ▁IV PP . ▁This ▁to oth ▁was ▁found ▁in ▁the ▁? T ith onian - age ▁? Upper ▁Jur ass ic ▁Ke il oz o ▁( now ▁Kal az ha ) ▁Form ation ▁of ▁X in ji ang , ▁China . ▁This ▁sp at ulate ▁to oth ▁crown ▁was ▁ ▁long , ▁and ▁was ▁not ▁unlike ▁that ▁of ▁the ▁younger ▁genus ▁A si at osa urus . ▁As ▁it ▁was ▁based ▁on ▁such ▁sparse ▁material , ▁it ▁has ▁largely ▁been ▁ignored ▁or ▁considered ▁to ▁be ▁ind ist ingu ish able ▁from ▁other , ▁better - known ▁sau rop ods . ▁For ▁example , ▁Russell ▁and ▁Zh eng ▁found ▁its ▁to oth ▁to ▁be ▁ind ist ingu ish able ▁from ▁those ▁of ▁M amen ch is aur us . ▁ ▁Boh lin ▁described ▁a ▁larger ▁to oth ▁in ▁the ▁ 1 9 5 3 ▁publication ▁as ▁" Spe cies ▁A . ▁( aff . ▁Chi ay ü sa urus )",