Two "missing" sharks discovered by studying weapons

People living by the sea have always made use of shark's teeth as points in various kinds of weapons. Scientists of the Field Museum of Natural History studied 120 weapons collected from the Gilbert Islands.  Attached to the clubs, lances, spears, and really awesome three-bladed swordlike weapons were the teeth of eight species of sharks.  All were known species, but two - the dusky and spotfin sharks - are found nowhere near the Gilberts.  Since the islanders didn't travel far, the most likely explanation is that these sharks were extinct in the areas - apparently before the first European explorers came along.   It may have been the Gilbertese liked their teeth a little too much.