Biology:Trachymetopon

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Short description: Extinct genus of fishes

Trachymetopon
Temporal range: Sinemurian-Callovian
~199–163.5 Ma
Possible Kimmeridgian record
Trachymetopon liasicum (cropped).JPG
Trachymetopon liassicum
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Sarcopterygii
Class: Actinistia
Order: Coelacanthiformes
Family: Mawsoniidae
Genus: Trachymetopon
Hennig, 1951
Species

Trachymetopon liasicum Hennig, 1951

Trachymetopon is an extinct genus of prehistoric coelacanth from the Jurassic of Europe. Fossils have been found in the Early Jurassic Posidonia Shale of Germany the Middle Jurassic Marnes de Dives of France , and probably the Late Jurassic Kimmeridge Clay of England.[1][2] Only one species has been named, Trachymetopon liassicum, described by Henning in 1951 from an almost complete specimen found in the Lower Toarcian of Ohmden in Baden-Württemberg.[3] Another specimen is known from the same site, and two older specimens come from the Sinemurian of Holzmaden.[4] The holotype of this species is 1.6 metres (5 ft 3 in) in length.[4] A giant specimen of an undetermined species of Trachymetopon found at the Middle Jurassic (Late Callovian) Falaises des Vaches Noires of Normandy. This specimen, composed of a 53 cm long palatoquadrate, belongs to an individual 4 metres (13 ft) in length.[5] A basisphenoid found in a museum in Switzerland that likely originates from the same locaity probably belonged to an individual around 5 m (16 ft) long, making Trachymetopon the largest of all coelacanths alongside Mawsonia.[1] A study published in 2015 revealed that this coelacanth belongs to the Mawsoniidae.[4] Trachymetopon is one of the few known mawsoniids to have been exclusively marine (with an indeterminate form from the Triassic of France), while most of the other members of the group have lived in fresh and brackish waters.[6]

Phylogeny

A phylogenetic analysis of the mawsoniids published in 2020 found a polytomy grouping together Trachymetopon and the Cretaceous genera “Lualabaea”, Axelrodichthys, and Mawsonia. The genus “Lualabaea” could be congeneric with Axelrodichthys.[7]

Outgroup

Diplurus

Parnaibaia

Chinlea

Trachymetopon liassicum

“Mawsonia” lavocati

Mawsonia

Axelrodichthys + “Lualabaea

See also

  • Sarcopterygii
  • List of sarcopterygians
  • List of prehistoric bony fish

References

  1. 1.0 1.1 Cavin, Lionel; Piuz, André; Ferrante, Christophe; Guinot, Guillaume (2021-06-03). "Giant Mesozoic coelacanths (Osteichthyes, Actinistia) reveal high body size disparity decoupled from taxic diversity" (in en). Scientific Reports 11 (1): 11812. doi:10.1038/s41598-021-90962-5. ISSN 2045-2322. PMID 34083600. Bibcode2021NatSR..1111812C. 
  2. Toriño, Pablo; Gausden, Shane F.; Etches, Steve; Rankin, Kathryn; Marshall, John E. A.; Gostling, Neil J. (2022). "An enigmatic large mawsoniid coelacanth (Sarcopterygii, Actinistia) from the Upper Jurassic Kimmeridge Clay Formation of England". Journal of Vertebrate Paleontology 42 (1): e2125813. doi:10.1080/02724634.2022.2125813. Bibcode2022JVPal..42E5813T. 
  3. Hennig, E. (1951). Trachymetopon liassicum, Ald., ein Reisen-Crossopterygier aus Schwäbischem Ober-Lias. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, Stuttgart, 94, 67-79.
  4. 4.0 4.1 4.2 Dutel, H.; Herbin, M.; Clément, G. (2015). "First Occurrence of a Mawsoniid Coelacanth in the Early Jurassic of Europe". Journal of Vertebrate Paleontology 35 (3): e929581. doi:10.1080/02724634.2014.929581. Bibcode2015JVPal..35E9581D. 
  5. Dutel, H.; Pennetier, E.; Pennetier, G. (2014). "A Giant Marine Coelacanth from the Jurassic of Normandy, France". Journal of Vertebrate Paleontology 34 (5): 1239–1242. doi:10.1080/02724634.2014.838176. Bibcode2014JVPal..34.1239D. 
  6. Deesri, U.; Cavin, L.; Amiot, R.; Bardet, N.; Buffetaut, E.; Cuny, G.; Giner, S.; Martin, J.E. et al. (2018). "A mawsoniid coelacanth (Sarcopterygii: Actinistia) from the Rhaetian (Upper Triassic) of the Peygros quarry, Le Thoronet (Var, southeastern France)". Geological Magazine 155 (1): 187–192. doi:10.1017/S0016756817000619. Bibcode2018GeoM..155..187D. 
  7. Cavin, L.; Buffetaut, E.; Dutour, Y.; Garcia, G.; Le Loeuff, J.; Méchin, A.; Méchin, P.; Tong, H. et al. (2020). "The last known freshwater coelacanths: New Late Cretaceous mawsoniids remains (Osteichthyes: Actinistia) from Southern France". PLOS ONE 15 (6): e0234183. doi:10.1371/journal.pone.0234183. PMID 32502171. Bibcode2020PLoSO..1534183C. 

Wikidata ☰ Q7831401 entry