▁ ▁Description C rypt ure ll us ▁members , ▁like ▁other ▁tin am ous , ▁have ▁a ▁crypt ic ▁color ▁scheme ▁domin ated ▁by ▁brow ns , ▁buff s , ▁y ell ows , ▁and ▁gre ys . ▁Un like ▁the ▁rest ▁of ▁the ▁family , ▁these ▁birds ▁show ▁some ▁sexual ▁dim orphism : ▁the ▁females ▁are ▁more ▁heavily ▁bar red ▁than ▁the ▁males ▁and ▁are ▁also ▁a ▁bit ▁br ighter ▁and ▁larger . ▁ ▁Range ▁The ▁majority ▁of ▁species ▁occup y ▁for ests ▁or ▁rain ▁for ests , ▁prefer ring ▁lower ▁elev ations . ▁They ▁range ▁from ▁Uruguay ▁to ▁Mexico . ▁However , ▁the ▁earliest ▁known ▁occurrence ▁of ▁the ▁genus ▁is ▁a ▁foss il ▁hum er us , ▁described ▁as ▁C rypt ure ll us ▁re ai , ▁from ▁the ▁Early ▁Mi oc ene ▁Santa ▁Cruz ▁Form ation ▁of ▁Pat ag onia . ▁ ▁V ocal ization C rypt ure ll us ▁are ▁a ▁very ▁loud ▁group ▁of ▁birds ▁with ▁mel od ious ▁calls . ▁They ▁tend ▁to ▁use ▁lower ▁frequency ▁when ▁they ▁call ▁than ▁other ▁members ▁of ▁the ▁T in am ou . ▁M ales ▁and ▁females ▁have ▁different ▁calls ▁and ▁each ▁species ▁also ▁has ▁different ▁calls . ▁Norm ally ▁each ▁sex ▁will ▁have ▁a ▁long ▁and ▁a ▁short ▁phrase ▁call . ▁The ▁genus ▁can ▁be ▁grouped ▁into ▁two ▁partial ▁groups ▁based ▁on ▁the ▁similarity ▁of ▁their ▁calls . ▁ ▁Group ▁ 1 ▁ ▁Und ulated ▁tin am ou ▁ ▁Red - leg ged ▁tin am ou ▁ ▁Y ellow -