mort em ▁treatment . ▁All ▁foss ils ▁were ▁buried ▁in ▁black / dark - b rown ▁t uff ace ous ▁sand ▁just ▁above ▁the ▁Mas aver a ▁Bas alt ▁( 1 . 8 5 ▁Ma ). ▁ ▁Tax onom ic ▁classification ▁▁ ▁Results ▁from ▁a ▁Princi pal ▁Com ponents ▁Analysis ▁( P CA ) ▁performed ▁by ▁Right m ire ▁et ▁al . ▁support ▁the ▁position ▁that ▁the ▁D man isi ▁spec im ens ▁represent ▁a ▁morph ological ▁middle ▁ground ▁between ▁H . ▁hab ilis ▁and ▁H . ▁ere ct us . ▁When ▁comparing ▁morph ological ▁tra its ▁which ▁are ▁statist ically ▁supported ▁to ▁best ▁represent ▁the ▁variation ▁between ▁all ▁H . ▁ere ct us ▁( sens u ▁l ato ) ▁spec im ens ▁( M and ib ular ▁f ossa ▁bread th , ▁sup ra orb ital ▁tor us ▁thick ness , ▁and ▁c ran ial ▁shape ), ▁all ▁five ▁D man isi ▁spec im ens ▁are ▁most ▁closely ▁associated ▁with ▁H . ▁erg aster , ▁with ▁only ▁Sk ull ▁ 5 ▁being ▁an ▁out lier ▁in ▁c ran ial ▁shape . ▁This ▁research ▁showed ▁that ▁the ▁seem ingly ▁large ▁variation ▁of ▁c ran io fa cial ▁dimensions ▁among ▁the ▁D man isi ▁sk ull s ▁is ▁no ▁greater ▁than ▁that ▁of ▁H . ▁ere ct us , ▁H . ▁s api ens , ▁and ▁P . ▁bo ise i . ▁Although ▁this ▁does ▁not ▁conclus ively ▁indicate ▁how ▁the ▁D man isi ▁spec im ens ▁should ▁be ▁class ified ▁tax in om