 Based on the skull originally referred to Anasazisaurus , the form of the complete crest is that of a tab or flange of bone , from the nasals , that rises between and above the eyes and folds back under itself . This unique crest allows it to be distinguished from similar hadrosaurs , like Gryposaurus . The top of the crest is roughened , and the maximum preserved length of the skull is ~ 90 centimeters ( ~ 35 in ) . 
