Cretoxyrhina mantelli was a large shark that lived about 100 to 82 million years ago, during the mid-Cretaceous period. It is nicknamed the "Ginsu shark" in reference to the Ginsu knife, since it fed by slicing into its victims with its knife-sharp teeth. It had no common name in the early literature, although over 30 synonyms were assigned to it. Its genus name is creto- (for "Cretaceous") prefixed to Oxyrhina ("sharp-nosed"), its original name.
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 the fossil hunter Charles H. Sternberg, who published his findings in 1907. The specimen comprised a nearly complete associated vertebral column and over 250 associated teeth. This kind of exceptional preservation of fossil sharks is rare, because a shark's skeleton is made of cartilage, which is not prone to fossilization. Charles dubbed the specimen Oxyrhina mantelli. This specimen represented a 20-foot-long (6 m) shark. It was excavated from Hackberry Creek, Gove County, Kansas.
Cretoxyrhina 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.
C. mantelli grew up to 7 metres (23 ft) long and rivaled the extant great white shark, Carcharodon carcharias in size.
Cretoxyrhina had 34 teeth in its upper jaw and 36 teeth in lower jaw, in each row. Its fossil teeth are up to 7 cm long, curved, and smooth-edged, with a thick enamel coating.
Cretoxyrhina lived in Cenomanian–Campanian seas worldwide, including in the Western Interior Seaway of North America.
Cretoxyrhina was the largest shark in its time and was among the chief predators of the seas. Fossil records revealed that it preyed on a variety of marine animals, such as mosasaurs like Tylosaurus, plesiosaurs like Elasmosaurus, bony fish like Xiphactinus, and protostegid turtles like Archelon.
Cretoxyrhina in The Land Before Time
A shark that may or may not be a depiction of a Cretoxyrhina appears in The Land Before Time V: The Mysterious Island as the secondary antagonist. He first appeared when Littlefoot, Petrie, Cera, Ducky and Spike rode a log across the Big Water to try to get back home, where he chased them, biting parts of the log off, and causing them to turn around until they hit a rock and were thrown back onto the island.
While running from the Plated Sharptooth, Littlefoot and his friends corner themselves at the island's edge leading into the ocean, and, just then, the shark passes by with its fin above the water. Cera reminds Petrie which Sharptooth is more important to worry about. Littlefoot later mistakes the head crest of Elsie the Elasmosaurus for another shark. The shark also appears on the box art of the fifth film.