Annakacygna is a genus of flightless marine swan from the Miocene of Japan. Named in 2022, Annakacygna displays a series of unique adaptations setting it apart from any other known swan, including a filter feeding lifestyle, a highly mobile tail and wings that likely formed a cradle for their hatchlings in a fashion similar to modern mute swans. Additionally, it may have used both wings and tail as a form of display. All of these traits combined have led the researchers working on it to dub it "the ultimate bird". Two species are known, A. hajimei, which was approximately the size of a black s
Annakacygna is a genus of flightless marine swan from the Miocene of Japan. Named in 2022, Annakacygna displays a series of unique adaptations setting it apart from any other known swan, including a filter feeding lifestyle, a highly mobile tail and wings that likely formed a cradle for their hatchlings in a fashion similar to modern mute swans. Additionally, it may have used both wings and tail as a form of display. All of these traits combined have led the researchers working on it to dub it "the ultimate bird". Two species are known, A. hajimei, which was approximately the size of a black swan, and A. yoshiiensis which exceeded the mute swan in both size and weight. The describing authors proposed the vernacular name Annaka short-winged swan for the genus.
==History and naming== The type specimen (GMNH-PV-678) of Annakacygna is a nearly complete, almost articulate skeleton discovered in the year 2000 by Hajime Nakajima close to the Usui river, Annaka, Gunma. The fossils were found encased in a slab of siltstone in sediments of the Haraichi Formation, a Miocene formation preserving a marine environment. Early research believed it to be a relative of Megalodytes, a flightless bird from the Miocene of western North America. Preparation of the material however showed that Annakacygna was a distinct taxon and it was described as such by Hiroshige Matsuoka and Yoshikazu Hasegawa in 2022. The second species, only known from a distal tibiotarsus (GMNH-PV-1685) unearthed in 1995, was collected from the riverbed of the Kabura River, 11.5 km further southeast than the remains of the type species. This fossil was donated to the Gunma Museum of Natural History in 2005.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).