▁and ▁W iw ax ia ▁could ▁perform ▁all ▁the ▁functions ▁of ▁the ▁multi - row ▁rad ula ▁– ▁r asp ing , ▁capt uring ▁sc rap ed ▁food , ▁sorting ▁it ▁and ▁transport ing ▁it ▁to ▁the ▁g ul let . ▁In ▁his ▁opinion ▁the ▁differences ▁between ▁the ▁nar ro wer ▁first ▁to oth - row ▁and ▁slightly ▁wider ▁second ▁one ▁in ▁both ▁Od ont og ri ph us ▁and ▁W iw ax ia ▁were ▁unlike ▁those ▁of ▁a ▁m oll us can ▁rad ula , ▁in ▁which ▁the ▁much ▁more ▁numerous ▁to oth - rows ▁are ▁identical ; ▁instead ▁he ▁argued ▁that ▁these ▁two ▁rows ▁res emble d ▁the ▁permanent ▁lower ▁j aw ▁and ▁mol table ▁upper ▁j aw ▁of ▁modern ▁dor ville id ▁pol ych a etes . ▁ ▁While ▁But ter field ▁agreed ▁that ▁the ▁dark ▁patch es ▁round ▁the ▁foot ▁served ▁as ▁g ills , ▁he ▁denied ▁that ▁they ▁were ▁similar ▁in ▁structure ▁and ▁mode ▁of ▁development ▁to ▁m oll us can ▁c ten idia . ▁In ▁his ▁opinion ▁the ▁fl atten ed ▁remains ▁of ▁Od ont og ri ph us ▁were ▁formed ▁by ▁relatively ▁t ough ▁ext rac ell ular ▁secret ions , ▁such ▁as ▁j aws , ▁br ist les ▁and ▁t ough ened ▁skin , ▁and ▁do ▁not ▁include ▁purely ▁or ▁primarily ▁cell ular ▁t issues , ▁such ▁as ▁mus cles ▁or ▁g on ads . ▁He ▁therefore ▁thought ▁the ▁resp ir atory ▁org ans ▁round ▁the ▁edge ▁of ▁Od ont og ri ph us ’