ation ▁is ▁a ▁ge olog ic ▁formation ▁of ▁the ▁Camp an ian ▁Age ▁during ▁the ▁C ret ace ous ▁Period , ▁found ▁in ▁California ▁and ▁southern ▁Oregon . ▁ ▁Ge ology ▁The ▁C en oz o ic ▁Era ▁formation ▁can ▁region ally ▁over lie ▁the ▁Va quer os ▁Form ation , ▁and ▁can ▁region ally ▁under lie ▁the ▁Mart ine z ▁Form ation ▁or ▁Te jon ▁Form ation . ▁ ▁The ▁Ch ico ▁Form ation ▁is ▁exposed ▁in ▁the ▁Southern ▁California ▁Coast ▁R anges , ▁western ▁San ▁Jo aqu in ▁Valley , ▁north ▁of ▁Mount ▁Di ablo , ▁and ▁in ▁the ▁Ch ico ▁area ▁of ▁the ▁n ort he astern ▁Sac r amento ▁Valley . ▁ ▁It ▁is ▁also ▁found ▁in ▁the ▁eastern ▁Sim i ▁Hills ▁in ▁Bell ▁C any on ▁and ▁Day ton ▁C any on , ▁located ▁in ▁Los ▁Angeles ▁and ▁Vent ura ▁Count ies , ▁near ▁the ▁community ▁of ▁West ▁Hills . ▁ ▁Pale of a una ▁Din osa ur ▁remains ▁are ▁among ▁the ▁foss ils ▁that ▁have ▁been ▁recovered ▁from ▁the ▁formation , ▁from ▁the ▁Late ▁C ret ace ous ▁of ▁the ▁Mes oz o ic ▁Era . ▁ ▁Species ▁The ▁l izard ▁and ▁bird ▁species ▁listed ▁in ▁the ▁table ▁below ▁date ▁from ▁the ▁Late ▁C ret ace ous ▁E po ch . ▁ ▁See ▁also ▁▁ ▁List ▁of ▁foss il ifer ous ▁strat ig raph ic ▁units ▁in ▁California ▁ ▁List ▁of ▁din osa ur - b ear ing ▁rock ▁form ations ▁ ▁List ▁of ▁strat ig raph