Amakusaichthys
Extinct genus of ray-finned fishes From Wikipedia, the free encyclopedia
Amakusaichthys is an extinct genus of ichthyodectiform ray-finned fish which lived during the Late Cretaceous, known from two species A. goshouraensis from Kumamoto Prefecture in Japan[1] and A. benammii from Chiapas in Mexico.[2]
| Amakusaichthys Temporal range: | |
|---|---|
| |
| Skull of A. gosyouraensis | |
 | |
| Type specimen of A. benammii | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | †Ichthyodectiformes |
| Family: | †Heckelichthyidae |
| Genus: | †Amakusaichthys Yabumoto et al. 2018 |
| Type species | |
| †Amakusaichthys goshouraensis Yabumoto et al. 2018 | |
| Other species | |
| |
Discovery
Fossils of A. goshouraensis were discovered in 2012 from construction site in Goshoura, Amakusa.[3] This site is later considered to belong to Hinoshima Formation of the Himenoura Group.[1] 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) are from non-marine environment.[1][3]
Second species, A. benammii is described from Angostura Formation in Tzimol Quarry, Chiapas, southeastern Mexico.[2]
Description
Amakusaichthys is relatively small ichthyodectiform with length around 60 cm (24 in). It is characterized by its long snout and small mouth and teeth.[1] Multiple specimens are found overlapped in one place, suggesting its schooling ecology.[3][4]
Classification
Amakusaichthys was not assigned to any family in original description. However, characters suggested that it was related to Heckelichthys.[1] In 2021, it was assigned to Bardackichthyidae, alongside Heckelichthys and Bardackichthys.[5] However, a 2024 paper which described a new species A. benammii placed both Amakusaichthys and Heckelichthys (with Garganoichthys and Altamuraichthys as other probable members) into a separate family Heckelichthyidae, and questioned the inclusion of Bardackichthys and Chuhsiungichthyidae within Ichthyodectiformes.[2]
References
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