▁FM N H   PR 2 2 6 0 ▁is ▁more ▁or ▁less ▁complete , ▁primarily ▁lack ing ▁some ▁b ones ▁from ▁the ▁rear ▁of ▁the ▁sk ull . ▁The ▁ske leton ▁is ▁well - art ic ulated , ▁with ▁numerous ▁rows ▁of ▁o ste od erm s ▁remaining ▁in ▁place ▁beneath ▁the ▁tail , ▁but ▁is ▁somewhat ▁fl atten ed . ▁The ▁animal ▁appears ▁to ▁have ▁been ▁an ▁adult ▁when ▁it ▁died . ▁It ▁diff ers ▁from ▁Shin is aur us ▁in ▁a ▁few ▁details . ▁For ▁example , ▁FM N H   PR 2 2 6 0 ▁had ▁a ▁proportion ally ▁longer ▁sn out ▁and ▁an ▁additional ▁to oth ▁in ▁the ▁upper ▁j aw , ▁and ▁its ▁post orb ital ▁and ▁post front al ▁b ones ▁were ▁not ▁f used . ▁ ▁Pale o ec ology ▁Bah nd w iv ici ▁is ▁one ▁of ▁several ▁l iz ards ▁known ▁from ▁the ▁F oss il ▁But te ▁Member ▁of ▁the ▁Green ▁River ▁Form ation . ▁This ▁rock ▁unit ▁represents ▁part ▁of ▁F oss il ▁Lake , ▁the ▁smallest ▁and ▁short est - l ived ▁of ▁three ▁pre histor ic ▁lake ▁systems ▁that ▁make ▁up ▁the ▁Green ▁River ▁Form ation . ▁The ▁lake ▁sed iments ▁include ▁a ▁vol can ic ▁ash ▁d ating ▁to ▁ 5 1 . 6 6 ▁million ▁years ▁ago , ▁during ▁the ▁Early ▁E oc ene . ▁F oss ils ▁are ▁abund ant ▁in ▁the ▁rocks ▁of ▁F oss il ▁Lake , ▁and ▁illustrate ▁a ▁diverse ▁assemb lage ▁of