 Ceratopsians are easily recognized by features of the skull . On the tip of a ceratopsian upper jaw is the rostral bone , an edentulous ( toothless ) ossification , unique to ceratopsians . Othniel Charles Marsh recognized and named this bone , which acts as a mirror image of the predentary bone on the lower jaw . This ossification evolved to morphologically aid the mastication of plant matter . Along with the predentary bone , which forms the tip of the lower jaw in all ornithischians , the rostral forms a superficially parrot @-@ like beak . Also , the jugal bones below the eye are very tall and flare out sideways , making the skull appear somewhat triangular when viewed from above . This triangular appearance is accentuated in later ceratopsians by the rearwards extension of the parietal and squamosal bones of the skull roof , to form the neck frill . 
 Ceratopsians are easily recognized by features of the skull . On the tip of a ceratopsian upper jaw <a href='drop_aux' title='1'><mark>is</mark></a>the rostral bone , an edentulous ( toothless ) ossification , unique to ceratopsians . Othniel Charles Marsh recognized and named this bone , which <a href='uninflect' title='2'><mark>acts</mark></a> as a mirror image of the predentary bone on the lower jaw . This ossification evolved to morphologically aid the mastication of plant matter . Along with the predentary bone , which <a href='uninflect' title='3'><mark>forms</mark></a> the tip of the lower jaw in all ornithischians , the rostral <a href='uninflect' title='4'><mark>forms</mark></a> a superficially parrot @-@ like beak . Also , the jugal bones below the eye <a href='drop_aux' title='5'><mark>are</mark></a>very tall and flare out sideways , making the skull appear somewhat triangular when viewed from above . This triangular appearance is accentuated in later ceratopsians by the rearwards extension of the parietal and squamosal bones of the skull roof , to form the neck frill . 
Ceratopsians are easily recognized by features of da skull . On the tip of a ceratopsian upper jaw the rostral bone , an edentulous ( toothless ) ossification , unique to ceratopsians . Othniel Charles Marsh recognized and named this bone , which act as a mirror image of the predentary bone on tdalower jaw . dis ossification evolved to morphologically aid thdaastication of plant matter . Along w/ the predentary bone , which form thedap of the daer jaw in all ornithischians , the rdaral form a superficially parrot @-@ like beak . Also , the juda bones below the eyedary tall and flare out sideways , makin the skuldappear somewhat triangular when viewed from above . Tdistriangular appearance is accentuated in later ceratopsians by the rearwdas extension of the parietal and squamosal bones of the skull roof , to form the neck frill .