Xiphactinus
Encyclopedia
Xiphactinus was a large, 4.5 to 6 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). The Portheus molossus described by Cope is a junior synonym of the species. Skeletal remains of Xiphactinus have come from Kansas
(where the first Xiphactinus fossil was discovered during the 1850s), Alabama
, and Georgia
in the United States, as well as Europe
, Australia
and Canada
.
Xiphactinus audax was a voracious predator fish. At least a dozen specimens have been collected with the remains of large, undigested or partially digested prey in their stomachs. In particular, one 13 feet (4 m) fossil specimen was collected by George F. Sternberg
with another, nearly perfectly preserved 6 feet (1.8 m) 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.
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 tooth bearing premaxilla
and lower jaws of an individual estimated to be about 12 inches (30.5 cm) long.
The species and all other ichthyodectids went extinct near the end of the Late Cretaceous
as the Western Interior Seaway
began to recede from the middle of North America - 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.
In July 2010 the bones of a Xiphactinus were discovered near Morden, Manitoba, Canada. The specimen is about six metres long and was found with the flipper of a mosasaur
between its jaws.
.
In October 2010, Kansas House Rep. Tom Sloan (R-Lawrence) announced that he would introduce legislation to make Xiphactinus, the "X-fish," the state fossil of Kansas.
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.)"
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."
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, during the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. When alive, the fish would have resembled a gargantuan, fanged tarpon
Tarpon
Tarpons are large fish of the genus Megalops. There are two species of Megalops, one native to the Atlantic, and the other to the Indo-Pacific oceans.They are the only members of the family Megalopidae.- Species and habitats :...
(to which it was, however, not related). The Portheus molossus described by Cope is a junior synonym of the species. Skeletal remains of Xiphactinus have come from Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
(where the first Xiphactinus fossil was discovered during the 1850s), Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
, and Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
in the United States, as well as Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
.
Palaeobiology
George F. Sternberg
George Fryer Sternberg was a paleontologist best known for his discovery in Gove County, Kansas of the "fish-within-a-fish" of Xiphactinus audax. He was the son of Charles Hazelius Sternberg and nephew of Brig. Gen. George M. Sternberg...
with another, nearly perfectly preserved 6 feet (1.8 m) long ichthyodectid Gillicus arcuatus
Gillicus arcuatus
Gillicus arcuatus was a relatively small, 2-metre long ichthyodectid fish that lived in the Western Interior Seaway, in what is now central North America, during the Late Cretaceous. Like its larger relative, Ichthyodectes ctenodon, G...
, 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.
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
Squalicorax
Squalicorax is a genus of extinct lamniform shark known to have lived during the Cretaceous period. A fully articulated 1.9 m long fossil skeleton of Squalicorax has been found in Kansas, evidence of its presence in the Western Interior Seaway...
). 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 tooth bearing premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
and lower jaws of an individual estimated to be about 12 inches (30.5 cm) long.
The species and all other ichthyodectids went extinct near the end of the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
as the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
began to recede from the middle of North America - see Cretaceous-Tertiary extinction event
Cretaceous-Tertiary extinction event
The Cretaceous–Paleogene extinction event, formerly named and still commonly referred to as the Cretaceous-Tertiary extinction event, occurred approximately 65.5 million years ago at the end of the Maastrichtian age of the Cretaceous period. It was a large-scale mass extinction of animal and plant...
.
An incomplete skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
of what may be a new species of Xiphactinus was found in 2002 in the Czech Republic
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
, in a small town called Sachov next Borohradek
Borohrádek
Borohrádek is a town in the Hradec Králové Region of the Czech Republic. It has circa 2,150 inhabitants.-External links:*...
city, by student Michal Matejka.
In July 2010 the bones of a Xiphactinus were discovered near Morden, Manitoba, Canada. The specimen is about six metres long and was found with the flipper of a mosasaur
Mosasaur
Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764...
between its jaws.
In popular culture
X. audax was one of the predators featured in the BBC's Sea Monsters, as well as National Geographic's Sea Monsters: A Prehistoric AdventureSea Monsters: A Prehistoric Adventure
Sea Monsters: A Prehistoric Adventure is a film by National Geographic which is set in the Earth's prehistoric past. The film features state-of-the-art three dimensional photographic and computer generated characters/animals. The setting alternates between prehistory and modern day times in which...
.
In October 2010, Kansas House Rep. Tom Sloan (R-Lawrence) announced that he would introduce legislation to make Xiphactinus, the "X-fish," the state fossil of Kansas.
Further reading
- 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.
- 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 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. 1870. [Remarks on ichthyodorulites and on certain fossil Mammalia.]. Proceedings of the Academy of Natural Sciences of Philadelphia. 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).
- 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.
- 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."
- Stovall, J. W. 1932. Xiphactinus audax, a fish from the Cretaceous of Texas. University of Texas Bulletin No. 3201:87-92, 1 pl.
- Walker, M.V. 1982. The Impossible Fossil. University Forum, Fort Hays State University 26: 4pp.