▁to ▁the ▁west . ▁The ▁depos its ▁from ▁their ▁east - f acing ▁d rain age ▁bas ins ▁were ▁carried ▁by ▁streams ▁and ▁rivers ▁and ▁depos ited ▁in ▁sw amp y ▁low lands , ▁la kes , ▁river ▁channels , ▁and ▁flo od pla ins . ▁This ▁formation ▁is ▁similar ▁in ▁age ▁to ▁the ▁L our in h ã ▁Form ation ▁in ▁Portugal ▁and ▁the ▁T end ag uru ▁Form ation ▁in ▁T anz ania . ▁ ▁A pat osa urus ▁was ▁the ▁second ▁most ▁common ▁sau rop od ▁in ▁the ▁Mor r ison ▁Form ation ▁e cos ystem , ▁after ▁Cam ar as aur us . ▁A pat osa urus ▁may ▁have ▁been ▁more ▁solit ary ▁than ▁other ▁Mor r ison ▁Form ation ▁din osa urs . ▁F oss ils ▁of ▁the ▁genus ▁have ▁only ▁been ▁found ▁in ▁the ▁upper ▁levels ▁of ▁the ▁formation . ▁Those ▁of ▁A pat osa urus ▁ajax ▁are ▁known ▁exclus ively ▁from ▁the ▁upper ▁Br ush y ▁Bas in ▁Member , ▁about ▁ 1 5 2 – 1 5 1 ▁my a . ▁A . lou is ae ▁foss ils ▁are ▁rare , ▁known ▁only ▁from ▁one ▁site ▁in ▁the ▁upper ▁Br ush y ▁Bas in ▁Member ; ▁they ▁date ▁to ▁the ▁late ▁Kim mer id g ian ▁stage , ▁about ▁ 1 5 1 my a . ▁Add itional ▁A pat osa urus ▁remains ▁are ▁known ▁from ▁similarly ▁aged ▁or ▁slightly ▁younger ▁rocks , ▁but ▁they ▁have ▁not ▁been ▁identified ▁as ▁any ▁particular ▁species , ▁and