text: if a megalodon existed could they come up from the mariana trench?   carcharodon megalodon   a big, big shark... what's the biggest, most aggressive, most fearsome shark you can think of? well, that would have to be the great white shark, white death, carcharodon carcharias. a shark measuring up to 23 feet in length, and having teeth up to 2 inches long. ouch.     now, what if this shark was twice as big? hmmm...  now, what if this shark was four times as big, or bigger? gulp.  and what if this shark might still be alive?  now we're talking megalodon.     carcharodon megalodon is the great white shark's big brother! estimated to be exactly like the great white shark in proportion, but two to six times larger. that's a total of anywhere from 50 to 120 feet in length! and teeth up to 8 inches in length!  ok, so what's all this about this shark being alive? well, the reason we know that this shark even existed is that we've found its teeth. its teeth? that's right. sharks don't have bones­they are made out of cartilage, so they can't leave any bones behind for us to study. but their teeth do fossilize and they hang around for a long time! we've found megalodon's teeth and they are almost exactly like carcharodon carcharias's teeth, only bigger­ much bigger. and guess what? some of the teeth we've found weren't fossilized, they were recent! how recent? ten to twenty years old. holy smokes! that means that this shark was swimming in our seas as recently as ten to twenty years ago! has anyone ever seen it? well, there are lots of eyewitness accounts, some of them estimating the shark at up to 300 feet in length (!), and even some sonar accounts.  but are they tall fish tales? or are they real?   hmmm...megalodon...    --------------------------------------------------------------------------------   need more info on the meg? may we suggest:  "meg, a novel of deep terror" by steve alten (isbn 055357910x). fictional, of course, but a great shark story!!!!! available on audiocassette too. scientific accuracy is pretty good up until the end where it rather fails. but don't blame us for our recommendation if you don't want to go in the water afterwards!  "let's go fossil shark tooth hunting" by b. clay cartmell (isbn 0930498011). a super guide to fossilized teeth, which is pretty much all we have to go on with our chondrichthyes chums. provides some good background on how teeth become fossilized, as well as how to identify them. it has a nice write up on our friend.  http://www.megalodonteeth.com/  http://www.elasmo.com/selachin/gw/c_extn.html  http://www.megalodonteeth.com/html/gift.html  http://www.fossilshark.com  http://www.strangemag.com/megalodon.html  http://www.megalodonteeth.com/html/about.html  http://www.flmnh.ufl.edu/fish/research/white/megatoothshark.htm  http://www.elasmo.com/selachin/gw/cvc_intr.html   american museum of natural history, ny- they have a reconstruction of megalodon's jaws.  "kelley's guide to fossil sharks" by k. v. kelley, jr.  "fossil sharks: a pictoral review" by gerard r. case  "blue meridian, the search for the great white shark" by peter matthiessen (isbn 0140265139)  "size of the great white shark" by john e. randall published in "science"