▁James ▁La Po inte ▁has ▁explicitly ▁called ▁Un kte hi ▁a ▁din osa ur . ▁ ▁The ▁Si oux ▁of ▁the ▁Stand ing ▁Rock ▁Res ervation , ▁which ▁str add les ▁the ▁border ▁between ▁North ▁and ▁South ▁Dak ota , ▁have ▁a ▁long ▁history ▁of ▁familiar ity ▁with ▁din osa ur ▁b one bed s . ▁They ▁interpreted ▁the ▁b ones ▁as ▁the ▁remains ▁of ▁mon str ous , ▁evil ▁ser p ents ▁that ▁tun ne led ▁under ground . ▁Light ning ▁continu ously ▁sought ▁to ▁kill ▁the ▁ser p ents ▁and ▁successful ▁k ills ▁became ▁number ed ▁with ▁the ▁abund ant ▁local ▁foss ils . ▁The ▁light ning ▁had ▁been ▁so ▁dev ast ating ▁to ▁the ▁area ▁that ▁it ▁was ▁responsible ▁for ▁the ▁conversion ▁of ▁the ▁region ▁to ▁bad lands ▁and ▁the ▁Si oux ▁avoid ▁physical ▁contact ▁with ▁the ▁foss ils ▁out ▁of ▁fear ▁that ▁doing ▁so ▁might ▁make ▁themselves ▁more ▁likely ▁to ▁be ▁killed ▁by ▁light ning . ▁ ▁Scient ific ▁research ▁ ▁The ▁first ▁scientific ally ▁documented ▁foss ils ▁in ▁North ▁Dak ota ▁were ▁collected ▁during ▁the ▁Lewis ▁and ▁Clark ▁expedition ▁between ▁ 1 8 0 4 ▁and ▁ 1 8 0 6 ▁as ▁they ▁mapped ▁the ▁course ▁of ▁the ▁Missouri ▁River . ▁The ▁first ▁foss il ▁written ▁about ▁in ▁the ▁state ▁were ▁pet r ified ▁wood ▁preserved ▁in ▁sand stone ▁con cret ions ▁discovered ▁at ▁the ▁C annon ball ▁River . ▁In ▁ 1 8 3 3 ▁a ▁German ▁named ▁Alexander ▁Philip ▁Maxim ilian ▁observed ▁leaf ▁impress ions ▁preserved