Cretoxyrhina

Cretoxyrhina Temporal range: Late Cretaceous
Restoration
Conservation status
Fossil
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Superorder:	Selachimorpha
Order:	Lamniformes
Family:	†Cretoxyrhinidae
Genus:	Cretoxyrhina
Species:	C. mantelli
Binomial name
Cretoxyrhina mantelli

Cretoxyrhina mantelli was a large shark that lived during the Cretaceous period, about 100 to 82 million years ago. It is commonly known as the Ginsu Shark.

Known physiology

A Cretoxyrhina and two Squalicorax circling around a dead Claosaurus

Identification and preserved specimens

This shark was first identified by a famous Swiss Naturalist, Louis Agassiz in 1843, as Cretoxyhrina mantelli. However, the most complete specimen of this shark was discovered in 1890, by a fossil hunter, Charles H. Sternberg. He published his findings of this specimen in 1907. This specimen comprising nearly complete associated vertebral column and over 250 associated teeth. Such kind of exceptional preservation of fossil sharks is rare because shark's skeleton is made of cartilage, which is not prone to fossilization. Charles dubbed this specimen Oxyrhina mantelli. This specimen represented a 20-foot-long (6.1 m) shark. It was excavated from Hackberry creek, Gove county, Kansas.^[1]

In later years, several other specimens have also been found. One such specimen was discovered in 1891 by George Sternberg, and was stored in a Munich museum. This specimen was also reported to be 20 feet long but was destroyed during a bombing raid on Munich in World War II.^[1]

Common name

Cretoxyhrina mantelli had no common name in the early literature and over 30 synonyms were assigned to it.^[1] Since it fed by slicing its victims into bite-size pieces, paleontologists, K. Shimada and M. J. Everhart, gave it the name Ginsu Shark.^[2] The word Ginsu refers to slicing and dicing.

Physical anatomy

The Ginsu shark is among the most well understood fossil sharks to date. Several preserved specimens have revealed a great deal of insight about the physical features and lifestyle of this ancient predatory shark.

Dentition

Cretoxyrhina sp. teeth at the Geological Museum, Copenhagen

The fossil teeth of C. mantelli are up to 7 cm long,^[3] curved, and smooth-edged, with a thick enamel coating.

The Ginsu shark had 34 teeth in its upper jaw and 36 teeth in lower jaw, in each row.^[1]

Size

C. mantelli grew up to 7 metres (23 ft) long and rivaled the extant great white shark, Carcharodon carharias in size.

Physical appearance

The specimen from Niobrara Chalk of western Kansas supports the idea that the body form of C. mantelli resembled that of the existing great white shark.^[4] The caudal fin morphology of the Ginsu shark indicates that it was an active shark, capable of fast swimming.^[4]

Range

This shark lived in Cenomanian–Campanian seas worldwide, including in the Western Interior Seaway of North America.^[4]

Dietary preferences

The Ginsu shark was the largest shark in its time and was among the chief predators of the seas. Fossil records revealed that it preyed upon a variety of marine animals such as, Mosasaurs,^[5] Plesiosaurs,^[6] Xiphactinus,^[7] and protostegid turtles.^[8]

See also

• Prehistoric fish

	Paleontology portal
	Sharks portal

References

1. ^ ^{a b c d} Everhart, Mike. "A GIANT GINSU SHARK (Cretoxyrhina mantelli Agassiz) From Late CRETACEOUS Chalk of KANSAS". http://www.oceansofkansas.com/BigShark.html. 
2. ^ Everhart, Mike. "Cretoxyrhina mantelli - The Ginsu Shark". http://www.oceansofkansas.com/ginsu.html. 
3. ^ Everhart, Mike. "Large Sharks in the Western Interior Sea". http://www.oceansofkansas.com/sharks/Kansas/fickcret.jpg. 
4. ^ ^{a b c} Shimada, Kenshu, Cumbaa, S. L., Rooyen, D. V. (2006). Caudal Fin Skeleton of the LATE CRETACEOUS LAMNIFORM SHARK, CRETOXYRHINA MANTELLI, from the NIOBRARA CHALK OF KANSAS. New Mexico Museum of Natural History. http://www.nmnaturalhistory.org/science/bulletins/35/sci_bulletin35_22.pdf. Retrieved 2009-10-02. ^{[dead link]}
5. ^ Rothschild, B. M. (2005). "Sharks eating mosasaurs, dead or alive?". Netherlands Journal of Geosciencesvolume 21 (4): 335–340. http://www.njgonline.nl/publish/articles/000268/article.pdf. Retrieved 2009-10-02. 
6. ^ Everhart, M. J. (2005). Bite marks on an elasmosaur (Sauropterygia; Plesiosauria) paddle from the Niobrara Chalk (Upper Cretaceous) as probable evidence of feeding by the lamniform shark, Cretoxyrhina mantelli. PalArch Foundation. http://www.palarch.nl/wp-content/everhart_mj_bite_marks_on_an_elasmosaur_sauropterygia_plesiosauria_paddle_from_the_niobrara_chalk_upper_cretaceous_as_probable_evidence_of_feeding_by_the_lamniform_shark_cretoxyrhina_mantelli_palarchs.pdf. Retrieved 2009-10-02. 
7. ^ Shimada, Kenshu (1997). "Paleoecological relationships of the Late Cretaceous lamniform shark, Cretoxyrhina mantelli (Agassiz)". Journal of Paleontology. http://findarticles.com/p/articles/mi_qa3790/is_199709/ai_n8760035/pg_5/?tag=content;col1. Retrieved 2009-10-02. 
8. ^ Shimada, Kenshu, Hooks, G. E. (2004). "SHARK-BITTEN PROTOSTEGID TURTLES from the UPPER CRETACEOUS MOOREVILLE CHALK, ALABAMA". Journal of Paleontology. http://findarticles.com/p/articles/mi_qa3790/is_200401/ai_n9368107/. Retrieved 2009-10-02. 

External links

• Fact File from National Geographic

Educational videos

• Mega Beasts: Sea of Killers