ch , ▁d ating ▁back ▁five ▁million ▁years . ▁Disc over ies ▁have ▁been ▁made ▁there ▁of ▁the ▁remains ▁of ▁cam el ids , ▁be ars , ▁be a vers , ▁fro gs , ▁sn akes , ▁t urt les , ▁and ▁several ▁previously ▁unknown ▁species ▁of ▁rod ents . ▁ ▁Two ▁fish ▁tax a , ▁b ull head ▁( A me i urus ) ▁and ▁sun fish ▁( C entr arch idae ), ▁have ▁also ▁been ▁found ▁there . ▁ ▁Origin ▁and ▁importance ▁Pi pe ▁Creek ▁S ink hole ▁pres erves ▁an ▁ancient ▁wet land . ▁It ▁was ▁created ▁by ▁the ▁collapse ▁of ▁a ▁lim estone ▁cave ▁in ▁a ▁Sil ur ian ▁re ef ▁formation . ▁That ▁left ▁a ▁ste ep - s ided ▁de pression ▁about ▁ ▁long , ▁ ▁wide ▁and ▁ ▁deep . ▁When ▁water ▁collected ▁in ▁the ▁de pression , ▁it ▁became ▁the ▁habitat ▁of ▁the ▁plants ▁and ▁animals ▁whose ▁remains ▁were ▁preserved ▁there ▁when ▁the ▁sink hole ▁was ▁buried ▁by ▁gla cial ▁out w ash ▁and ▁till ▁during ▁the ▁Ple ist oc ene ▁E po ch , ▁two ▁million ▁to ▁ 1 1 , 0 0 0 ▁years ▁ago . ▁ ▁While ▁the ▁e col ogy ▁of ▁the ▁P li oc ene ▁in ▁North ▁America ▁is ▁well - known ▁from ▁foss il ▁discover ies ▁in ▁other ▁places , ▁not ably ▁coast al ▁sites , ▁the ▁Ple ist oc ene ▁gla ci ers ▁destroyed ▁or ▁scattered ▁most ▁of ▁the ▁foss il ▁remains ▁in ▁the ▁continent ' s ▁interior