Xiphactinus

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Xiphactinus
Temporal range:
Ma
Mounted skeleton of X. audax at the American Museum of Natural History
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: †Ichthyodectiformes
Family: †
Ichthyodectidae
Subfamily: †
Ichthyodectinae
Genus: †Xiphactinus
Leidy, 1870
Type species
†Xiphactinus audax
Leidy, 1870
Species[1]
  • † X. audax Leidy, 1870
  • † X. vetus Leidy, 1856
Synonyms
List of synonyms[2][3]
  • Synonyms of X. audax
      • Saurocephalus audax Cope, 1870
      • Saurocephalus thaumas Cope, 1870
      • Portheus molossus Cope, 1871
      • Portheus thaumas Cope, 1871
      • Portheus lestrio Cope, 1873
      • Portheus mudgei Cope, 1874
      • Portheus lowii Stewart, 1898
      • Xiphactinus molossus Stewart, 1898
      • Xiphactinus thaumas Stewart, 1898
      • Xiphactinus brachygnathus Stewart, 1899
      • Xiphactinus lowii Stewart, 1900
      • Xiphactinus gaultinus Newton, 1877
      • Xiphactinus mantelli Newton, 1877
      • Megalodon sauroides Agassiz, 1835
      • Megalodon? lewesiensis Mantell, 1836
      • Hypsodon lewesiensis Agassiz, 1843
      • Portheus mantelli Newton, 1877
      • Portheus daviesi Newton, 1877
    Synonyms of X. vetus
      • Polygonodon vetus Leidy, 1856
      • Polygonodon rectus Emmons, 1858
      • Mossasaurus rectus Emmons, 1858[a]
      • Portheus angulatus Cope, 1872
      • Xiphactinus angulatus Schwimmer et al., 1992

Xiphactinus (from

teleosts
.

The species Portheus molossus described by Cope is a

Niobrara Chalk),[6][7] and Cretaceous formations all over the East Coast (most notably Georgia, Alabama, North Carolina, and New Jersey) in the United States,[6][3] as well as Europe, Australia,[8] the Kanguk and Ashville Formations of Canada,[6] La Luna Formation of Venezuela and the Salamanca Formation in Argentina.[6][4][9]

Paleobiology

Restoration of X. audax
Gillicus arcuatus
swallowed whole.

Species of Xiphactinus were voracious predatory fish. At least a dozen specimens of X. audax have been collected with the remains of large, undigested or partially digested prey in their stomachs. In particular, one 4.2 metres (14 ft) fossil "Fish-Within-A-Fish" specimen was collected by

Sternberg Museum of Natural History in Hays, Kansas.[10]

Like many other species in the Late Cretaceous oceans, a dead or injured individual was likely to be scavenged by sharks (Cretoxyrhina and Squalicorax). The remains of a Xiphactinus were found within a large specimen of Cretoxyrhina collected by Charles H. Sternberg. The specimen is on display at the University of Kansas Museum of Natural History.

Detailed view of the skull of Xiphactinus at the American Museum of Natural History

Like modern tarpons, Xiphactinus likely spent its juvenile stage of life in shallow seaway margins for protection and to utilize rich food resources, possibly rare in open marine water, though this needs confirmation due to the lack of shallow, nearshore deposits from the Western Interior Seaway. The teeth of the juvenile specimen indicate that the diet of Xiphactinus probably didn't change notably during its growth, implying that even the small specimens would have been fish-eating predators.[11]

"Unicerosaurus"

In 1982, a former Baptist minister,

Niobrara Chalk" that Baugh's museum "declared to be the forehead horn of a newly discovered dinosaur genus".[12] The museum's exhibit told visitors that the "horn" belonged to "the unicorn of Job 38, one of three dinosaurs mentioned in Scripture; the others being behemoth and leviathan of Job 40 and 41", and that the horn was able to fold back like the blade of a jack knife. Although some Young Earth Creationists shared Baugh's interpretations of the biblical Behemoth and Leviathan, Baugh's claims were not taken seriously either by Christian organizations or the scientific community.[citation needed
]

ichthyodectids
Depiction of a Xiphactinus swallowing a Gillicus

In October 2010, Kansas House Rep. Tom Sloan (R-Lawrence) announced that he would introduce legislation to make Xiphactinus audax, a.k.a. the "X-fish", the state fossil of Kansas.[13] Ultimately, Tylosaurus was selected instead.[14][15]

Notes

  1. ^ sic

References

  1. ^
    doi:10.18435/B5H596
    .
  2. hdl:1808/3814
    .
  3. ^
    JSTOR 4523841
    .
  4. ^
    S2CID 216170146
    .
  5. S2CID 83807640
    .
  6. ^ a b c d Xiphactinus at Fossilworks.org
  7. ISBN 978-1-55407-181-4
    . The first Xiphactinus fossil was found during the 1850s in Kansas.
  8. doi:10.18435/B5H596
    .
  9. ^ Carrillo-Briceño, J., Alvarado-Ortega, J. & Torres, C. (2012). Primer registro de Xiphactinus Leidy, 1870, (Teleostei: Ichthyodectiformes) en el Cretácico Superior de América del Sur (Formación La Luna, Venezuela). Revista Brasileira de Paleontologia 15(3):327-335
  10. ^ Konishi, T., Newbrey, M. G., & Caldwell, M. W. (2014). A small, exquisitely preserved specimen of Mosasaurus missouriensis (Squamata, Mosasauridae) from the upper Campanian of the Bearpaw Formation, western Canada, and the first stomach contents for the genus. Journal of Vertebrate Paleontology, 34(4), 802–819. https://doi.org/10.1080/02724634.2014.838573
  11. S2CID 191146942
    .
  12. ^ Armstrong, John R. (1987). Creation/Evolution Newsletter 7 5:21; Geolog. 16, Part 4.
  13. ^ "Kansas Rep. Tom Sloan agrees to back X-fish as state's official fossil / LJWorld.com". .ljworld.com. Associated Press. 2010-10-26. Retrieved 2011-10-12.
  14. ^ "State Fossils - Kansapedia - Kansas Historical Society".
  15. ^ "List of State Fossils". State Symbols, State Fossil. Fossilera. Retrieved September 1, 2015.


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