ens ▁of ▁Cruz iana ▁are ▁commonly ▁found ▁associated ▁together ▁at ▁one ▁sed iment ary ▁horizon , ▁suggesting ▁that ▁the ▁traces ▁were ▁made ▁by ▁populations ▁of ▁ar th rop ods . ▁ ▁References ▁ ▁Further ▁reading ▁ ▁External ▁links ▁Track ways ▁and ▁associated ▁bur row ; ▁Ph oto -- ( Close - up ); ▁Graph ic -- ( tr il ob ite ▁and ▁bur row , ▁etc ) ▁Argent ine ▁article ▁on ▁Cruz iana ▁" Rem ark able ▁Cruz iana ▁b eds ▁in ▁the ▁Lower ▁Ord ov ician ▁of ▁the ▁Cord ill era ▁Oriental , ▁N W ▁Argentina ". ▁ ▁Category : Ar th rop od ▁trace ▁foss ils ▁Category : F oss il ▁track ways <0x0A> </s> ▁P ry m nb ri are us ▁nim ber lin us ▁is ▁a ▁species ▁of ▁air - bre ath ing ▁land ▁sn ail , ▁a ▁terrest rial ▁pul mon ate ▁g ast rop od ▁m oll usk ▁in ▁the ▁family ▁C ama en idae . ▁This ▁species ▁is ▁en demic ▁to ▁Australia . ▁ ▁References ▁ ▁S lack - Smith , ▁S . ▁ 1 9 9 6 . ▁ ▁P ry m nb ri are us ▁nim ber lin us . ▁▁▁ 2 0 0 6 ▁IU CN ▁Red ▁List ▁of ▁Th re aten ed ▁Species . ▁▁ ▁Down loaded ▁on ▁ 7 ▁August ▁ 2 0 0 7 . ▁ ▁Category : G ast rop ods ▁of ▁Australia ▁nim ber lin us ▁Category : G ast rop ods ▁described ▁in ▁ 1 9 8