▁made ▁by ▁other ▁ar th rop ods . ▁Cruz iana ▁appears ▁in ▁non - marine ▁form ations ▁such ▁as ▁the ▁Be acon ▁Super group ▁that ▁would ▁have ▁been ▁un su itable ▁environments ▁for ▁tr il ob ites , ▁and ▁in ▁Tri ass ic ▁sed iments ▁that ▁were ▁depos ited ▁after ▁tr il ob ites ▁became ▁ext inct ▁at ▁the ▁end ▁of ▁the ▁Perm ian ▁Period . ▁ ▁Cruz iana ▁traces ▁can ▁reach ▁ 1 5   mm ▁across ▁and ▁ 1 5   cm ▁in ▁length , ▁with ▁one ▁end ▁usually ▁deeper ▁and ▁wider ▁than ▁the ▁other . ▁The ▁bur row ▁may ▁begin ▁or ▁end ▁with ▁a ▁rest ing ▁trace ▁called ▁Rus oph y cus , ▁the ▁outline ▁of ▁which ▁corresponds ▁roughly ▁to ▁the ▁outline ▁of ▁the ▁trac em aker , ▁and ▁with ▁sculpt ure ▁that ▁may ▁reve al ▁the ▁approximate ▁number ▁of ▁legs , ▁although ▁stri ations ▁( scr atch marks ) ▁from ▁a ▁single ▁leg ▁may ▁overlap ▁or ▁be ▁repeated . ▁ ▁Cruz iana ▁ten ella , ▁and ▁conce iv ably ▁other ▁ich nos pecies , ▁appears ▁to ▁have ▁been ▁formed ▁by ▁the ▁concaten ation ▁of ▁a ▁series ▁of ▁Rus oph y cus ▁traces , ▁suggesting ▁that ▁Cruz iana ▁is ▁a ▁feed ing ▁trace , ▁rather ▁than ▁a ▁locomot ory ▁trace ▁formed ▁by ▁bur row ing ▁within ▁a ▁layer ▁of ▁mud ▁as ▁histor ically ▁believed . ▁▁ ▁The ▁ich n ogen us ▁Di pl ich n ites ▁may ▁be ▁produced ▁where ▁the ▁track maker ▁sp ed ▁up . ▁Several ▁spec im