 The bird was sexually dimorphic : males were larger and had proportionally longer beaks . The beak was up to 23 centimetres ( 9 @.@ 1 in ) in length and had a hooked point . The upper bill was nearly twice as long as the cranium , which was short compared to those of its closest pigeon relatives . The openings of the bony nostrils were elongated along the length of the beak , and they contained no bony septum . The cranium ( excluding the beak ) was wider than it was long , and the frontal bone formed a dome , with the highest point above the hind part of the eye sockets . The skull sloped downwards at the back . The eye sockets occupied much of the hind part of the skull . The sclerotic rings inside the eye were formed by eleven ossicles ( small bones ) , similar to the amount in other pigeons . The mandible was slightly curved , and the hind part was expanded to the side . 
