▁related ▁to ▁P elor osa urus . ▁However , ▁it ▁was ▁not ▁until ▁the ▁description ▁of ▁new , ▁nearly ▁complete ▁sau rop od ▁ske let ons ▁from ▁the ▁United ▁States ▁( re present ing ▁A pat osa urus ▁and ▁Cam ar as aur us ) ▁later ▁that ▁year ▁that ▁a ▁complete ▁picture ▁of ▁sau rop ods ▁emer ged . ▁An ▁approximate ▁reconst ruction ▁of ▁a ▁complete ▁sau rop od ▁ske leton ▁was ▁produced ▁by ▁artist ▁John ▁A . ▁Ry der , ▁h ired ▁by ▁pale ont ologist ▁E . D . ▁C ope , ▁based ▁on ▁the ▁remains ▁of ▁Cam ar as aur us , ▁though ▁many ▁features ▁were ▁still ▁in ac cur ate ▁or ▁incomplete ▁according ▁to ▁later ▁finds ▁and ▁bi ome chan ical ▁studies . ▁Also ▁in ▁ 1 8 7 7 , ▁Richard ▁Ly dek ker ▁named ▁another ▁relative ▁of ▁Cet ios aur us , ▁T itan osa urus , ▁based ▁on ▁an ▁isolated ▁verte bra . ▁ ▁In ▁ 1 8 7 8 , ▁the ▁most ▁complete ▁sau rop od ▁yet ▁was ▁found ▁and ▁described ▁by ▁O th n iel ▁Charles ▁Marsh , ▁who ▁named ▁it ▁Di pl od ocus . ▁With ▁this ▁find , ▁Marsh ▁also ▁created ▁a ▁new ▁group ▁to ▁contain ▁Di pl od ocus , ▁Cet ios aur us , ▁and ▁their ▁increasing ▁ro ster ▁of ▁relatives ▁to ▁differenti ate ▁them ▁from ▁the ▁other ▁major ▁groups ▁of ▁din osa urs . ▁Marsh ▁named ▁this ▁group ▁Sau rop oda , ▁or ▁" l izard ▁feet ". ▁