You could drive a Volkswagen Beetle through these jaws.

The shark that once gnashed them was 40 feet long. That's nothing. Sometimes Carcharodon megalodon, the ancestor of the Great White, would run 100 feet long.

Luckily for us and the Volkswagen people, it has been extinct 4 million years.

Even after all this time, those triangular teeth, sharp as kitchen knives and delicately serrated, draw blood. Walter Hock, the Smithsonian model maker who put the new exhibit together at the Museum of Natural History, has cuts on his forehead from working inside the jaws.

The exhibit opens Oct. 12 in the fossil gallery.

In the beginning the Museum of Natural History had just 48 teeth, some of them more than 6 inches long, found by amateur collector Peter J. Harmatuk in a North Carolina phosphate pit. He donated them three years ago, along with hundreds of other specimens dug up over 25 years.

Working from the teeth and the structure of the Great White's jaw, Hock and his colleagues Jessica Harrison, Robert Emry and Victor Springer, plus John Maisey from New York's American Museum of Natural History, put together this life-size reproduction of the largest shark jaw known.

On the wall behind the new exhibit are silhouettes of a 17-foot Great White and -- utterly engulfing it -- the 40-foot Megalodon.

Also on view are some whale bones that look as though somebody has been at them with a power saw. The shark would bite down on a huge chunk of whale and worry it like a dog with a gopher.

If only they hadn't mentioned those 100-footers. Maybe there's one still cruising around down there . . . duh-dum, duh-dum . . .