Sharks continually shed their teeth; some Carcharhiniformes shed approximately 35,000 teeth in a lifetime, replacing those that fall out. There are four basic types of shark teeth: dense flattened, needle-like, pointed lower with triangular upper, and non-functional. The type of tooth that a shark has depends on its diet and feeding habits.
Fossil shark teeth (Cretaceous) from southern Israel
Otodus megalodon fossil shark jaw (reconstruction) (late Cenozoic) 2
An O. megalodon tooth excavated from Lee Creek Mine, Aurora, North Carolina, United States.
Scapanorhynchus texanus, Menuha Formation (Upper Cretaceous), southern Israel.
Stingrays are a group of sea rays, a type of cartilaginous fish. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae, Plesiobatidae, Urolophidae (stingarees), Urotrygonidae, Dasyatidae, Potamotrygonidae, Gymnuridae and Myliobatidae .
There are about 220 known stingray species organized into 29 genera.
Stingray
Early Eocene fossil stingray Heliobatis radians
dorsal (topside) ← → ventral (underside) External anatomy of a male bluntnose stingray (Hypanus say)
Stingray jaw and teeth. The teeth are modified placoid scales.