Polymixia

Polymixia
Temporal range: Early Paleocene–present Possible Late Cretaceous occurrence
Stout beardfish (P. nobilis)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Polymixiiformes
Family: Polymixiidae
Genus: Polymixia
R. T. Lowe, 1838
Type species
Polymixia nobilis

Polymixia is the only extant genus of the order Polymixiiformes and family Polymixiidae. It contains 10 species, all of which live in deepwater marine environments.[1] They are found in tropical and subtropical waters of the Atlantic, Indian and western Pacific Oceans. They are bottom-dwelling fish, found down to about 800 m (2,600 ft). Most are relatively small fish, although one species is over 40 cm (16 in) in length.[2] They can be considered "living fossils" due to being the only surviving members of the once-diverse order Polymixiiformes.[3]

Classification

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There are currently 12 recognized species in this genus:[1]

The extinct species Polymixia polita Schwarzhans, 2012 is known from fossil otoliths from the early and late Paleocene of Germany and Austria.[6] Another otolith-based taxon that may possibly belong to this genus, Polymixia? harderi (Schwarzhans, 2003) is known from the late Maastrichtian and early Paleocene of Denmark, in addition to a potential earlier record from the Campanian of North Carolina, USA; this may suggest Late Cretaceous origins for the genus.[7][8]

References

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  1. ^ a b Froese, Rainer; Pauly, Daniel (eds.). "Species in genus Polymixia". FishBase. February 2017 version.
  2. ^ Paxton, John R. (1998). Paxton, J.R.; Eschmeyer, W.N. (eds.). Encyclopedia of Fishes. San Diego: Academic Press. p. 161. ISBN 0-12-547665-5.
  3. ^ De Cia Caixeta, Heloísa; Oliveira, Claudio; Melo, Marcelo Roberto Souto de (2024-03-01). "Another piece of the living fossil puzzle: A new species of Polymixia Lowe, 1836 (Polymixiiformes: Polymixiidae) from the western South Atlantic". Deep Sea Research Part I: Oceanographic Research Papers. 205: 104249. doi:10.1016/j.dsr.2024.104249. ISSN 0967-0637.
  4. ^ De Cia Caixeta, Heloísa; Oliveira, Claudio; Melo, Marcelo Roberto Souto de (2024-03-01). "Another piece of the living fossil puzzle: A new species of Polymixia Lowe, 1836 (Polymixiiformes: Polymixiidae) from the western South Atlantic". Deep Sea Research Part I: Oceanographic Research Papers. 205: 104249. doi:10.1016/j.dsr.2024.104249. ISSN 0967-0637.
  5. ^ Grande, Terry C.; Wilson, Mark V. H. (2021-07-16). "A New Cryptic Species of Polymixia (Teleostei, Acanthomorpha, Polymixiiformes, Polymixiidae) Revealed by Molecules and Morphology". Ichthyology & Herpetology. 109 (2). doi:10.1643/i2020112. ISSN 2766-1512.
  6. ^ Schwarzhans, Werner (2012). "Fish otoliths from the Paleocene of Bavaria (Kressenberg) and Austria (Kroisbach and Oiching-Graben) / / Werner Schwarzhans". Palaeo Ichthyologica. 12: 1–88.
  7. ^ "Bulletin Volume 65 – 2017". Dansk Geologisk Forening (in Danish). 2017-02-15. doi:10.37570/bgsd-2017-65-05. Retrieved 2024-07-28.
  8. ^ Stringer, Gary L.; Clements, Don; Sadorf, Eric; Shannon, Kevin (2019). "First Description and Significance of Cretaceous Teleostean Otoliths (Tar Heel Formation, Campanian) from North Carolina". Eastern Paleontologist. 4: 1–22. ISSN 2475-5117.