▁described ▁by ▁him ▁until ▁ 1 8 9 2 . ▁Marsh ▁also ▁described ▁a ▁second ▁species ▁in ▁the ▁same ▁paper , ▁which ▁he ▁named ▁C im ol opter y x ▁ret usa , ▁but ▁this ▁has ▁since ▁been ▁recognized ▁as ▁a ▁different ▁kind ▁of ▁bird ▁and ▁rec lass ified ▁as ▁Pal int rop us ▁ret us us . ▁ ▁Classification ▁and ▁species ▁The ▁classification ▁of ▁various ▁species ▁assigned ▁to ▁the ▁genus ▁C im ol opter y x ▁has ▁changed ▁over ▁the ▁years , ▁and ▁many ▁species ▁once ▁thought ▁to ▁belong ▁to ▁this ▁genus ▁have ▁been ▁rec lass ified ▁or ▁de emed ▁ind et erm inate . ▁As ▁of ▁a ▁re - evalu ation ▁of ▁the ▁foss il ▁remains ▁in ▁ 2 0 0 2 ▁by ▁Syl via ▁Hope , ▁at ▁most ▁five ▁species ▁were ▁recognized : ▁C im ol opter y x ▁r ara , ▁C . ▁pet ra , ▁C . ▁maxim a , ▁C . ▁min ima , ▁and ▁one ▁yet - unn amed ▁species . ▁C . ▁r ara ▁and ▁C . ▁pet ra ▁were ▁considered ▁almost ▁identical , ▁and ▁found ▁in ▁the ▁same ▁environments ▁( the ▁L ance ▁and ▁French man ▁form ations ), ▁but ▁differ ed ▁in ▁size , ▁with ▁C . ▁pet ra ▁smaller ▁than ▁C . ▁r ara . ▁In ▁a ▁ 2 0 0 9 ▁review , ▁Nicholas ▁Long rich ▁syn onym ized ▁them ▁as ▁the ▁same ▁species , ▁dismiss ing ▁the ▁size ▁difference ▁as ▁possibly ▁based ▁on ▁gender ▁or ▁growth ▁stage . ▁However ,