actually there are longstanding questions on that.
Sharks teeth may have been one of the very earliest hafted points. Potentially as old as rock.
There are very old points that appear to be modeled after sharks teeth. Show shark teeth characteristics that aren't necessarily good for a point but were simply copied.
Also indians from cahokia to florida have made bone points that appear to be ceremonial but in great numbers with many shark teeth characteristics. and found in burial plots also containing small amounts of actual shark teeth.
Bare in mind cahokia is in IL not that close to the coast so they were probably of significance in some way or another. They could've just been jewelry but considering the arrowheads and the use of plummets as well even they they don't fish much its a better chance it is of historical signficance to them.
I had a thread up a while ago and some info was in it. I think in the one about archery prehistory. Badminton Library.
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=063345;p=1#000000