Amphistium Explained

Amphistium paradoxum (from Greek, Modern (1453-);: ἀμφί, 'on both sides', Greek, Modern (1453-);: ιστίον 'sail', and Greek, Modern (1453-);: παράδοξος 'extraordinary'),^[1] the only species classified under the genus Amphistium and the family Amphistiidae, is a fossil fish which has been identified as a Paleogene relative of the flatfish, and as a transitional fossil.^[2] In a typical modern flatfish, the head is asymmetric with both eyes on one side of the head. In Amphistium, the transition from the typical symmetric head of a vertebrate is incomplete, with one eye placed near the top of the head.^[3]

Amphistium is among the many fossil fish species known from the Monte Bolca Lagerstätte of Ypresian Italy. Heteronectes is a related, and very similar fossil from a slightly earlier strata of France. Heteronectes is sometimes also placed in the family Amphistiidae, though other studies find it to be more basal than any other flatfish taxon.^{[4] [5]}

Notes and References

1. Book: Roberts . George . An etymological and explanatory dictionary of the terms and language of geology . 1839 . Longman, Orme, Brown, Green, & Longmans . London . 7, 145 . 29 December 2021 . English.
2. News: Odd Fish Find Contradicts Intelligent-Design Argument . https://web.archive.org/web/20080711035445/http://news.nationalgeographic.com/news/2008/07/080709-evolution-fish.html . dead . July 11, 2008 . . July 9, 2008 . 2008-07-17.
3. Matt Friedman. The evolutionary origin of flatfish asymmetry. Nature. 454. 2008-07-10. 209–212. 10.1038/nature07108. 18615083. 7201. 2008Natur.454..209F. 4311712.
4. Friedman . Matt . 2012 . Osteology of † Heteronectes chaneti (Acanthomorpha, Pleuronectiformes), an Eocene stem flatfish, with a discussion of flatfish sister-group relationships . Journal of Vertebrate Paleontology . en . 32 . 4 . 735–756 . 10.1080/02724634.2012.661352 . 0272-4634.
5. Near . Thomas J . Thacker . Christine E . 18 April 2024 . Phylogenetic classification of living and fossil ray-finned fishes (Actinopterygii) . Bulletin of the Peabody Museum of Natural History . 65 . 10.3374/014.065.0101 . free.