Hoplopteryx

Hoplopteryx
An undescribed Hoplopteryx from the Maastrichtian of Belgium
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Division: Teleostei
Order: Trachichthyiformes
Family: Trachichthyidae
Genus: †Hoplopteryx
Agassiz, 1838
Type species
†Hoplopteryx antiquus
Agassiz, 1838
Species

See text

Hoplopteryx is an extinct genus of slimehead[1] from the Late Cretaceous, lasting from the middle of the Cretaceous to the end. It is one of the best-known fossil trachichthyiforms, and was widespread across the Northern Hemisphere, from throughout Europe east to the Middle East and west to North America.[2]

Taxonomy

The following valid species are known:[3][4][5][6]

Life restoration of H. lewesiensis

A well-preserved specimen of Hoplopteryx is known from the Maastrichtian-aged Ciply-Malogne Phosphatic Chalk Formation, but still remains undescribed at the species level. Indeterminate remains are also known from the Maastricht Formation.[9]

The species ?H. ('Beryx') insculptus is only known from a well-preserved flank of scales. Although it has been previously attributed to Hoplopteryx, no reasoning has been given for this attribution, and its taxonomy thus remains uncertain. The apparent species "Hoplopteryx" lundensis Davis, 1890 from the Early Paleocene of Limhamns kalkbrott, Sweden has been reclassified into Proserranus.[9][13] The species "H." lewisi (Davis, 1887) from the Cenomanian-aged Sannine Formation of Lebanon has been reclassified into Stichopteryx.[14]

A well-preserved specimen of H. lewesiensis from the English Chalk with preserved in situ otoliths has allowed for the morphology of Hoplopteryx otoliths to be better understood, and allowed for the placement of several previously enigmatic otolith-based species within this genus. The morphology of Hoplopteryx otoliths appears to closely resemble those of modern derived trachichthyids, especially the extant Trachichthys & Hoplostethus. This clashes with its external morphology, which shows many features not present in modern trachichthyiforms, causing them to be generally considered stem-group trachichthyids.[7]

Description

Hoplopteryx had a dorsal fin supported by nine unjointed, bony rays, deeply forked, homocercal tail, a moderately developed anal fin, and a pelvic fin located well forward. The snout is quite short, the eyes fairly large, and both jaws of the upturned mouth hold small teeth.

Hoplopteryx was at a typical length 27 cm. The abundance of well-preserved Hoplopteryx remains throughout the English Chalk allowed for the construction of a time series measuring the body size of Hoplopteryx over the Cretaceous Thermal Maximum. These measurements suggest that as the climate warmed, the body size of Hoplopteryx significantly decreased[1]

Habitat

Specimens of H. syriacus from Lebanon

Hoplopteryx was a marine fish, living primarily in shallow chalk seas.[7] They also appear to have been dominant species in certain deepwater habitats as well, such as those that formed within the Mississippi Embayment near the end of the Cretaceous, with Hoplopteryx oscitans being the most common fish otolith found in the Owl Creek Formation.[15][10]

Sources

  • Fossils (Smithsonian Handbooks) by David Ward (Page 219)
  • Grandstaff, Barbara S.; Parris, David C. (2016). "A new species of Hoplopteryx from the Carlile Formation (Cretaceous) of South Dakota". Proceedings of the South Dakota Academy of Science. 95: 73–84.
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References

  1. 1 2 Griffiths, Chloe V.; Witts, James D.; Brown, Julie C. S.; Bernard, Emma L.; Twitchett, Richard J. (2025). "Slimehead Size Through Time: Testing the Temperature–Size Relationship in Late Cretaceous Trachichthyidae". Ecology and Evolution. 15 (10) e72026. Bibcode:2025EcoEv..1572026G. doi:10.1002/ece3.72026. ISSN 2045-7758. PMC 12461127. PMID 41019402.
  2. 1 2 Grandstaff, Barbara S.; Parris, David C. (2016-01-01). "A NEW SPECIES OF HOPLOPTERYX FROM THE CARLILE FORMATION (CRETACEOUS) OF SOUTH DAKOTA". Proceedings of the South Dakota Academy of Science. 95: 73–84.
  3. 1 2 3 Patterson, Colin (1964-07-02). "A review of mesozoic acanthopterygian fishes, with special reference to those of the English chalk". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 247 (739): 213–482. Bibcode:1964RSPTB.247..213P. doi:10.1098/rstb.1964.0003. ISSN 0080-4622.
  4. ↑ Murray, Alison M. (2016). "Mid-Cretaceous acanthomorph fishes with the description of a new species from the Turonian of Lac des Bois, Northwest Territories, Canada". Vertebrate Anatomy Morphology Palaeontology. 1 (1): 101–115. doi:10.18435/b5cc78.
  5. ↑ Geology, British Museum (Natural History) Department of; Woodward, Arthur Smith (1901). Catalogue of the Fossil Fishes in the British Museum (Natural History): Actinopterygian Teleostomi of the suborders Isospondyli (in part), Ostariophysi, Apodes, Percesoces, Hemibranchii, Acanthopterygii, and Anacanthini. order of the Trustees.
  6. ↑ "PBDB Taxon". paleobiodb.org. Archived from the original on 2025-12-11. Retrieved 2026-06-02.
  7. 1 2 3 4 5 Schwarzhans, Werner; Beckett, Hermione T.; Schein, Jason D.; Friedman, Matt (2018). "Computed tomography scanning as a tool for linking the skeletal and otolith-based fossil records of teleost fishes". Palaeontology. 61 (4): 511–541. Bibcode:2018Palgy..61..511S. doi:10.1111/pala.12349. hdl:2027.42/144669. ISSN 1475-4983.
  8. 1 2 3 4 Friedman, Matt; Beckett, Hermione T.; Close, Roger A.; Johanson, Zerina (2016). "The English Chalk and London Clay: two remarkable British bony fish Lagerstätten". Geological Society, London, Special Publications. 430 (1): 165–200. Bibcode:2016GSLSP.430..165F. doi:10.1144/SP430.18.
  9. 1 2 3 Friedman, Matt; Andrews, James V.; Saad, Hadeel; El-Sayed, Sanaa (2023-08-31). "The Cretaceous–Paleogene transition in spiny-rayed fishes: surveying "Patterson's Gap" in the acanthomorph skeletal record". Geologica Belgica. 26 (1–2): 1–23. Bibcode:2023GeolB..26....1F. doi:10.20341/gb.2023.002.
  10. 1 2 3 Stringer, Gary L.; Schwarzhans, Werner; Phillips, George; Lambert, Roger (2020-02-05). "Highly Diversified Late Cretaceous Fish Assemblage Revealed by Otoliths (Ripley Formation and Owl Creek Formation, Northeast Mississippi, Usa)". Rivista Italiana di Paleontologia e Stratigrafia. 126 (1). doi:10.13130/2039-4942/13013. ISSN 2039-4942.
  11. ↑ Bardack, David; Teller-Marshall, Susan (1982). First Cretaceous Specimens of the Beryciform Fish Hoplopteryx from North America and their Bearing on Acanthopterygian Evolution (Report). Texas Memorial Museum, The University of Texas at Austin.
  12. ↑ Palci, Alessandro; Jurkovšek, Bogdan; Kolar-Jurkovšek, Tea; Caldwell, Michael W. (2008-04-01). "New palaeoenvironmental model for the Komen (Slovenia) Cenomanian (Upper Cretaceous) fossil lagerstätte". Cretaceous Research. 29 (2): 316–328. Bibcode:2008CrRes..29..316P. doi:10.1016/j.cretres.2007.05.003. ISSN 0195-6671.
  13. ↑ Adolfssen, Jan S.; Milàn, Jesper; Friedman, Matt (2017-02-15). "Review of the Danian vertebrate fauna of southern Scandinavia". Bulletin of the Geological Society of Denmark. 65: 1–23. Bibcode:2017BuGSD..65....1A. doi:10.37570/bgsd-2017-65-01. ISSN 2245-7070.
  14. ↑ Maksoud, Sibelle; Hossny, Tamara El; Samankassou, Elias; Cavin, Lionel; Saad, Pierre Abi; Azar, Dany; Piuz, André (2025), Biostratigraphy and palaeoenvironments of the Upper Cretaceous fossil fish Konservat-Lagerstätten of Lebano, doi:10.21203/rs.3.rs-7269932/v1, retrieved 2026-06-02
  15. ↑ Schwarzhans, Werner; Stringer, Gary L. (2020-05-06). "Fish Otoliths from the Late Maastrichtian Kemp Clay (Texas, Usa) and the Early Danian Clayton Formation (Arkansas, Usa) and an Assessment of Extinction and Survival of Teleost Lineages Across the K-Pg Boundary Based on Otoliths". Rivista Italiana di Paleontologia e Stratigrafia. 126 (2). doi:10.13130/2039-4942/13425. ISSN 2039-4942.
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