Thursday, August 19, 2010

August 19, 2010 : Cretoxyrhina (Extinct)


Cretoxyrhina mantelli was a large shark that lived during the Cretaceous period, about 100 to 82 million years ago. It was featured in the "Prehistoric Sharks" episode of Paleoworld.

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.

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 WWII.

This shark had no common name in the early literature (i.e. over 30 synonyms were assigned), and since it fed by slicing up its victims into bite-size pieces, paleontologists, K. Shimada and M. J. Everhart, assigned the title of the Ginsu Shark to Cretoxyhrina mantelli. The word Ginsu refers to slicing and dicing.

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, Plesiosaurs, Xiphactinus, and protostegid turtles.

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