Amphistium

Amphistium Temporal range: Ypresian, 50–49 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Carangiformes
Suborder:	Pleuronectoidei
Family:	†Amphistiidae Boulenger, 1902
Genus:	†Amphistium Agassiz, 1835
Species:	†A. paradoxum
Binomial name
†Amphistium paradoxum Agassiz, 1835

Amphistium paradoxum (from Greek: ἀμφί amphi, 'on both sides', Greek: ιστίον istion 'sail', and Greek: παράδοξος paradoxus '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]

References

1. Roberts, George (1839). An etymological and explanatory dictionary of the terms and language of geology. London: Longman, Orme, Brown, Green, & Longmans. pp. 7, 145. Retrieved 29 December 2021.
2. "Odd Fish Find Contradicts Intelligent-Design Argument". National Geographic. July 9, 2008. Archived from the original on July 11, 2008. Retrieved 2008-07-17.
3. Matt Friedman (2008-07-10). "The evolutionary origin of flatfish asymmetry". Nature. 454 (7201): 209–212. Bibcode:2008Natur.454..209F. doi:10.1038/nature07108. PMID 18615083. S2CID 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. 32 (4): 735–756. doi:10.1080/02724634.2012.661352. ISSN 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. doi:10.3374/014.065.0101.