Naranbulagornis

Naranbulagornis was a quite large waterfowl, a fourth larger than the contemporary Anatalavis ; it was presumably the largest anseriform of its time, reaching the size of the modern coscoroba swan. The holotype, the proximal end of a right carpometacarpus from Naran-Bulag, reached 58 mm in length ; most notably, and contrarily to all other anseriforms, its pisiform process was positioned at the level of the proximal margin of the extensor process. The referred material, consisting in the distal fragment of a femur, was 61.1 mm long ; despite the lack of overlapping material, it was referred to the genus due to its large size, similar to that of the Oligocene swan Cygnopterus. The presence of an elongate scar on the laterocaudal surface of the shaft is typical of all swimming anseriforms ; it was particularly deep as in modern large ducks.^[1]

Naranbulagornis was a more proficient swimmer than the teal-sized presbyornithid that lived in its environment ; similarities are quite important with modern swans, suggesting similar ways of moving through water and land. It may not have been as specialized for diving.^[1]