''Amakusaichthys'' is an extinct genus of

ichthyodectiform Ichthyodectiformes is an extinct order of marine stem-teleost ray-finned fish. The order is named after the genus '' Ichthyodectes'', established by Edward Drinker Cope in 1870. Ichthyodectiforms are usually considered to be some of the closest ...

fish which lived during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

, known from only one species ''A. goshouraensis''. Fossils are known from

Kumamoto Prefecture is a Prefectures of Japan, prefecture of Japan located on the island of Kyūshū. Kumamoto Prefecture has a population of 1,748,134 () and has a geographic area of . Kumamoto Prefecture borders Fukuoka Prefecture to the north, Ōita Prefecture to ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

Discovery

Fossils were discovered in 2012 from construction site in Goshoura,

Amakusa , which means "Heaven's Grass," is a series of islands off the west coast of Kyushu, the southernmost of the four main islands of Japan. Geography The largest island of the Amakusa group is Shimoshima, which is 26.5 miles long and 13.5 mil ...

. This site is later considered to belong to Hinoshima Formation of the Himenoura Group. It was the first discovery of marine ichthyodectform fish described from Asia in detail, while other ichthyodectiform fish from Asia (three genera belong to

Chuhsiungichthyidae Ichthyodectiformes is an extinct order of marine stem-teleost ray-finned fish. The order is named after the genus ''Ichthyodectes'', established by Edward Drinker Cope in 1870. Ichthyodectiforms are usually considered to be some of the closest re ...

) are from non-marine environment.

Description

''Amakusaichthys'' is relatively small ichthyodectiform fish with length around . It is characterized by its long snout and small mouth and teeth. Multiple specimens are found overlapped in one place, suggesting its

schooling A school is an educational institution designed to provide learning spaces and learning environments for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is sometimes compuls ...

ecology.

Classification

''Amakusaichthys'' was not assigned to any family in original description. However, characters suggested that it was related to '' Heckelichthys''. In 2021, it was assigned to Bardackichthyidae, alongside ''Heckelichthys'' and '' Bardackichthys''.

References

{{Taxonbar, from1=Q65236916, from2=Q97371573 Ichthyodectiformes Prehistoric ray-finned fish genera Santonian genera Fossils of Japan Late Cretaceous fish of Asia Late Cretaceous bony fish Fossil taxa described in 2018