This is a set of both, upper jaw and lower jaw fossil shark teeth from the extinct Broad-Toothed Mako (Broad-Toothed White) shark called Isurus hastalis. An extinct shark that was believed to be a member of the White Shark family, teeth from Isurus hastalis look remarkably similar to the modern Great White Shark less the serrations. Some consider this shark the "Grandfather of the Great White".
In this set, a lower jaw tooth shows the classic narrow profile compared to the wider upper jaw tooth. In the jaws of a shark, the upper and lower jaw teeth can be compared to how a knife and fork function. The narrow lower teeth act like a fork holding a piece of steak, while the broad upper teeth slice down like a knife. For an educational reference set of both teeth, this pair of fossil shark teeth demonstrate the difference in shape of each. Both teeth show a unique highly reflective chatoyance that flashes silvery tones beneath the dark bronze brown enamel.