| Chupkaornis | |
|---|---|
 | |
| A replica ofChupcaornis at the special exhibition "鳥" atNational Museum of Nature and Science,Tokyo | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Avialae |
| Clade: | †Hesperornithes |
| Genus: | †Chupkaornis Tanaka et al., 2017 |
| Type species | |
| †Chupkaornis keraorum Tanaka et al., 2017 | |
Chupkaornis (meaning "eastern bird"[1]) is a genus of prehistoricflightless birds from the LateCretaceous (Coniacian-Santonian)Kashima Formation ofHokkaido, Japan. Thetype species isChupkaornis keraorum.
It was discovered in August 1996 in the Late Cretaceous (Coniacian to Santonian)Kashima Formation of theYezo Group inMikasa, Hokkaido, and was donated to theMikasa City Museum and later exhibited in its permanent collection.[2] The fossils consist of nine bones: cervical vertebrae, torso vertebrae, femur, and fibula.[3] It was discovered as a new genus and species byHokkaido University and others in August 2017,[4] and described by Tomonori Tanaka,Yoshitsugu Kobayashi, Ken'ichi Kurihara,Anthony R. Fiorillo, and Manabu Kano.[5][6]
The left tarsometatarsus of a fragmentaryHesperornithes fossil discovered in theNishichirashinai Formation of the Yezo Group inNakagawa, Hokkaido, may belong to this genus because it is not included in the excavations of this genus.[7]
The genus nameChupkaornis refers to an eastern bird, as this bird was discovered in Japan in East Asia, as opposed toHesperornis, which means a western bird native to North America. It is also a combination of "chupka", meaning east inAinu, and "ornis", meaning bird inLatin. The specific namekeraorum is named after the brothers Kera Masatoshi and Kera Yasuji, who were amateur fossil collectors and discovered this species.[4][5]
Diagnostic traits ofChupkaornis include a finger-like projected tibiofibular crest of femur, deep, emarginated lateral excavation with a sharply defined edge of the ventral margin of the thoracic vertebrae, and the heterocoelous articular surface of the thoracic vertebrae.[6] Its body length was estimated at 70 metres (230 ft) to 80 metres (260 ft). Its legs were probably webbed, which allowed it to swim.[4]
Chupkaornis is recovered by Tanaka et al. (2017) as more derived than the Cenomanian-age formPasquiaornis, but less advanced thanBrodavis andBaptornis.[6] The followingcladogram shows the taxonomic position ofChupcaornis according to Hokkaido University:[5]
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