Xiphactinus

Taxobox
name = "Xiphactinus audax"

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image_caption = "Xiphactinus"
fossil_range = fossil range|100|65Late Cretaceous
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Pachycormiformes
familia = Ichthyodectidae
subfamilia = Ichthyodectinae
genus = "Xiphactinus"
species = "X. audax"
binomial = "Xiphactinus audax"
binomial_authority = Leidy, 1870

"Xiphactinus audax" Leidy (from Latin and Greek for "audacious sword-ray") was a large, 4.5 to 5 m (15 to 20 feet) long predatory bony fish that lived in the Western Interior Sea, over what is now the middle of North America, during the Late Cretaceous. When alive, the fish would have resembled a gargantuan, fanged tarpon (to which it was, however, not related). [ [http://www.oceansofkansas.com/Xiphac.html Xiphactinus audax Leidy ] ] "Portheus molossus" Cope. [ [http://www.oceansofkansas.com/Xiphac.html Xiphactinus audax Leidy ] ] is a junior synonym of the species. is Skeletal remains of "Xiphactinus" have come from Kansas, Alabama, and Georgia; Europe and Australia.

Palaeobiology

"Xiphactinus audax" was a voracious predatory fish. At least dozen specimens have been collected the remains of large, undigested or partially digested prey in their stomachs. In particular, [http://www.oceansofkansas.com/Sternbrg/xiphact2.jpgone 13 foot fossil specimen] was collected by George F. Sternberg with another, nearly perfectly preserved 6 foot long ichthyodectid "Gillicus arcuatus", inside of it. The larger fish apparently died soon after eating its prey, most likely due to the smaller fish prey struggling and rupturing an organ as it was being swallowed. This fossil can be seen at the Sternberg Museum of Natural History in Hays Kansas. [ [http://www.oceansofkansas.com/Xiphac.html Xiphactinus audax Leidy ] ]

Like many other species in the Late Cretaceous oceans, a dead or injured "X. audax" 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.

Virtually nothing is known about their larval or juvenile stages. The smallest fossil specimen of "X. audax" consists of a [http://www.oceansofkansas.com/Xiphactinus/XIPHJUV1.jpgtooth bearing premaxilla and lower jaws] of an individual estimated to be about 12 inches long. [ [http://www.oceansofkansas.com/Xiphac.html Xiphactinus audax Leidy ] ]

The species went extinct near the end of the Late Cretaceous as the Western Interior Sea began to recede from the middle of North America along with all the other ichthyodectids - see Cretaceous-Tertiary extinction event.

An incomplete skull of what may be a new species of "Xiphactinus" was found in 2002 in the Czech Republic, in a small town called Sachov next Borohradek city, by student Michal Matejka.

References:

[http://www.oceansofkansas.com/xiphac.html "Xiphactinus" page - Oceans of Kansas]

Bardack, D. 1965. Anatomy and evolution of Chirocentrid fishes. University of Kansas Paleontological Contributions, Article 10, 88 pp. 2 pl.

Cope, E. D. 1871. On the fossil reptiles and fishes of the Cretaceous rocks of Kansas. Art. 6, pp. 385-424 (no figs.) of Pt. 4, Special Reports, 4th Ann. Rpt., U.S. Geol. Surv. Terr. (Hayden), 511 p. (Cope describes and names "Portheus molossus")

Cope, E. D. 1872a. On Kansas vertebrate fossils. American Journal of Science, Series 3, 3(13):65.

Cope, E. D. 1872b. On the geology and paleontology of the Cretaceous strata of Kansas. Preliminary Report of the United States Geological Survey of Montana and Portions of the Adjacent Territories, Part III - Paleontology, pp. 318-349.

Cope, E. D. 1872c. [Sketch of an expedition in the valley of the Smoky Hill River in Kansas] . Proc. Amer. Phil. Soc. 12(87):174-176.

Cope, E. D. 1872d. On the families of fishes of the Cretaceous formation in Kansas. Proceedings of the American Philosophical Society 12(88):327-357.

Everhart, Michael J. 2005. "Oceans of Kansas - A Natural History of the Western Interior Sea". Indiana University Press, 320 pp.

Hay, O. P. 1898. Observations on the genus of fossil fishes called by Professor Cope, "Portheus", by Dr. Leidy, Xiphactinus. Zoological Bulletin 2(1): 25-54.

Hay, O. P. 1898. Observations on the genus of Cretaceous fishes called by Professor Cope "Portheus". Science, 7(175):646.Hay noted, "Professor O. P. Hay made some 'Observations on the genus of Cretaceous Fishes, called by Professor Cope "Portheus" " discussing the osteology of the genus at some length and particularly the skull, shoulder girdle and vertebral column. He said that in many respects it resembled the Tarpon of our Southern coasts, although possessing widely different teeth, and undoubtedly belonged to the Isospondyli. The conclusion reached that Cope's "Portheus" is identical with the earlier described genus "Xiphactinus" of Leidy. (Since the paper was read, the author has learned that Professor Williston has reached the same conclusion.)"

Leidy, J. 1856. Notices on remains of extinct vertebrated animals of New Jersey, collected by Prof. Cook of the State Geological Survey under the Direction of Dr. W. Kitchell. Proceedings of the Academy of Natural Sciences of Philadelphia, 8:221. (printed in 1857 - Naming of "Polygonodon vetus", a sister species of "Xiphactinus audax", and "Ischyrhiza mira" Leidy)

Leidy, J. 1865. Cretaceous reptiles of the United States. Smithsonian Contributions to Knowledge 14(6):1-135, pls. I-XX. (Three figures and a more detailed description of the tooth of "Polygonodon" ("Xiphactinus") "vetus" Leidy 1856)

Leidy, J. 1870. [Remarks on ichthyodorulites and on certain fossil Mammalia.] . Proc. Acad. Nat. Sci. Phil. 22:12-13. (The naming of "Xiphactinus audax" from a fragment of a pectoral fin found by Dr. George M. Sternberg (then an Army Surgeon serving in Kansas) in the chalk of western Kansas --- this paper pre-dates Cope's 1872 description of "Portheus molossus" by over a year).

Osborn, H. F. 1904. The great Cretaceous fish "Portheus molossus" Cope. Bull. Mus. Nat. Hist. Vol. 20, Art. 31, pp. 377-381, pl. 10. [AMNH 322199]

Rogers, K., 1991. A dinosaur dynasty: The Sternberg fossil hunters, Mountain Press Publishing Company, 288 pages.

Schwimmer, D. R., J. D. Stewart, and G. D. Williams. 1997. "Xiphactinus vetus" and the distribution of "Xiphactinus" species in the eastern United States. Journ. Vert. Paleo. 17(3):610-615.

Shimada, K. and M. J. Everhart. 2004. Shark-bitten "Xiphactinus audax" (Teleostei: Ichthyodectiformes) from the Niobrara Chalk (Upper Cretaceous) of Kansas. The Mosasaur 7, p. 35-39.

Sternberg, C. H. 1917. Hunting Dinosaurs in the Badlands of the Red Deer River, Alberta, Canada. Published by the author, San Diego, Calif., 261 pp.

Sternberg, C. H. 1922. Field work in Kansas and Texas. Kansas Academy of Science, Transactions 30(2):339-348.

Stewart, A. 1898. Individual variations in the genus "Xiphactinus" Leidy. Kansas Univ. Quar. 7(3):116-119, pl. VII, VIII, IX, X.Stewart placed a short note on page 116 acknowledging that Xiphactinus Leidy 1870 has priority over "Portheus" Cope 1872. "Xiphactinus audax" Leidy (Proc. Acad. Sci. Phila., 1870, p. 12) has been shown to the a synonym of "Saurocephalus" Cope (U.S. Geol. Surv., Wyoming, etc. 1872, p. 418). In a letter to Prof. Mudge, dated October 28, 1870, which will shortly be published in the fourth volume of the Kansas University Geological Survey, Cope refers it to "Saurocephalus thaumas" ("Portheus thaumas" Cope). After carefully comparing the description and figure of the pectoral spine of "X. audax" I was led to the same conclusion; and as the genus "Portheus" was not made known by Cope until 1871 (Proc. Am. Phil. Soc., 1871, p. 173), according to the rules of nonclamature "Xiphactinus" should have priority."

Stewart, A. 1899. Notice of three new Cretaceous fishes, with remarks on the Saurodontidae Cope. Kansas Univ. Quar. 8(3):107-112. ("Xiphactinus", "Protosphyraena gigas" and "Empo" ("Cimolichthys"))

Stewart, A. 1900. Teleosts of the Upper Cretaceous. The University Geological Survey of Kansas. Topeka 4:257-403, 6 figs., pls. 33-78.

Stovall, J. W. 1932. "Xiphactinus audax", a fish from the Cretaceous of Texas. University of Texas Bulletin No. 3201:87-92, 1 pl.

Thorpe, M. R. 1934. A new mounted specimen of "Portheus molossus" Cope. American Journal of Science, 5th series, 28(164):121-126, 2 fig.

Walker, M.V. 1982. The Impossible Fossil. University Forum, Fort Hays State University 26: 4pp.

Walker, M.V. 2006. The impossible fossil - Revisited. Kansas Academy of Science, Transactions 109 (1/2), p. 87-96.

References

External links

* [http://www.carnegiemnh.org/exhibits/jurassic/fctxipha.htm Carnegie Museum]
* [http://www.oceansofkansas.com/xiphac.html Oceans of Kansas]
* [http://homepages.dordt.edu/~mahaffy/paleo/fish/xiphactinus.html a painting and information]
* [http://www.bbc.co.uk/science/seamonsters/factfiles/xiphactinus.shtml BBC]