Cretoxyrhina mantelli, gigantic warm-blooded shark!

Cretoxyrhina (Agassiz, 1835) was a huge shark reaching up to 26’ long and nearly 4 tons, making it larger than today's Great White Shark!  Its teeth were built for “slicing and dicing,” stabbing with its front teeth and slicing off flesh with its side teeth.  The largest tooth thus far discovered was nearly 2 ½” long.  Its mouth could protrude like many sharks today, allowing it to take massive, deep bites.  It ate Xiphactinus, mosasaurs, plesiosaurs, sharks, fish, and turtles, and scavenged dinosaurs that washed out to sea.

Sharks, made of cartilage, rarely fossilize other than their teeth, as cartilage dissolves quickly upon death.  Cartilage can fossilize if the water conditions are right, essentially calcifying.  Such finds are extremely rare. However, in the Western Interior Seaway of Kansas, just such conditions have occurred occasionally, allowing paleontologists to find "body fossils" of Cretoxyrhina; basically, outlines of the body plus the cartilage itself had hardened into bone.  Such fossils are treasure troves of information and, in the case of Cretoxyrhina, showed paleontologists that the snout wasn't sharp, as was initially believed, but broad and blunt.  Such a blunt snout would have allowed the speedy predator to ram prey, as some sharks do today, stunning it before going in for a huge bite.  These fossils also revealed large eyes, giving it excellent vision.  

The preserved body outlines allowed paleontologists to determine how fast Cretoxyrhina swam, as certain tail angles indicate speed.  It was one of the fastest sharks ever to live, with a cruising speed of over 7 mph and bursts of over 43mph!  Today’s fastest shark, the shortfin Mako, has a top speed of 43mph. The Great White?  A paltry 35mph.  

It is likely Cretoxyrhina gave live birth to one or two 4’ long, 36 lb babies, with the rest of its baby sharks having been consumed in the womb!  The practice of eating one's wombmates is known as oophagy and happens in sharks today.  You can find videos online of intrauterine cameras capturing this macabre spectacle.

The Cretoxyrhina tooth in the crate comes from the Cretaceous of Kansas and was found near the teeth of Tylosaurus and Xiphactinus.  What a truly spectacular, and dangerous, place Kansas' ocean must have been 75 million years ago!

Thank you kindly,

BC