The beak was long and curved downwards as in the red rail, but the narial openings were longer. The premaxilla that comprised most of the upper bill was long, shallow in side-view, with a narrow nasal bone, and its total length was almost 60% longer than the cranium. The culmen of the beak was almost straight above the nostril, and the nasal bone was slightly longer than the cranium. The beak was up to long, the lower jaw up to long, and at its greatest depth. The narial (nostril) opening was very long, 66% of the rostrum's length. There were foramina (openings) on the upper bill, which did not extend to the front edge of the narial opening. The mandible was long and narroe, ending in a sharp point, with the length of the mandibular symphysis (the area where the halves of the mandible meet) being about 65% of the cranium's length. The mandible had large, deep set foramina, which ran almost up to a deep sulcus (furrow) at the centre of the mandible. Günther and Newton stated that the examined beaks varied greatly in size and shape; some specimens had short and almost straight beaks, while others had much longer beaks (up to one third longer) that were prominently curved. These writers were unsure whether this was related to the overall size of an individual bird or to sexual dimorphism. Livezy was unable to confirm the idea that the differences in the beaks reflected dimorphism in 2003, but thought it probable. Hume examined all available upper beaks in 2019, but found no differences in curvature.