 The nasals make up most of the crest . Brown assumed that they extended from the beaks ' tip to the highest spot along the crest and that , unlike those in other genera , the nasals meet in the centre and are not separated in front by an ascending premaxillary process . Brown however , mistook the praemaxillae for the nasals ; the snout is actually largely formed by them and they do separate the nasals . Brown also thought that on the top and back of the crest , the whole external face is covered by the frontals . Again he made a mistake : what he assumed to be the frontals are in fact the nasals . The nasals end at the back of the <unk> in a hooked , short process . The prefrontals also make up part of the crest ; however , Brown mistook the lower upper branch of the <unk> for the prefrontal . The actual prefrontal , triangular in shape , is located at the side of the crest base ; it was by Brown seen as a part of the frontal . The real frontals , largely internal to the crest base structure , are not visible from the side . 
