Edestus heinrichi xxxxxxxxxxxx ORDER: Eugenedontia 
Super Family: Edestoidea 
Family: Edestidae 
Genus: Edestus 
Species: heinrichi

The photo shows a group of 9 teeth  from a shark in the genus Edestus.  In this genus the tooth bases are enormously enlarged, and up to ten teeth may form in a group.  The bases are very tightly attached to each other (probably by connective tissue) but are not fused. ( The front is to the right ) 

The two left teeth are displaced in this sample, and the very right tooth is broken.  This type of shark shed their teeth and grew new ones throughout their life.  This grouping is called a symphysical tooth whorl.  Most if not all current species of sharks shed their teeth and grow new ones, it is estimated that a Great White shark may shed as many as 2,000 teeth per year. 

Approximate Age: 310-312 million years old.
Location of Discovery: Peabody Coal Co., Marissa Mine
Washington County., Illinois
 
The photo shows two different teeth from the genus Edestus.  The tooth bases were broken off before discovery.  Single teeth like these were probably shed while the shark was alive.
Approximate Age: 310-312 million years old.
Location of Discovery: Peabody Coal Co., Marissa Mine
Washington County., Illinois
This photo is from above, and shows the v-shaped groove into which the next-following, younger (posterior) tooth is nested. The tooth crown for this tooth is to the right of the v-groove.

Approximate Age: 310-312 million years old.
Location of Discovery: Peabody Coal Co., Marissa Mine
Washington County., Illinois
 
The above tooth group would be attached to the jaw by connective tissue.  The jaws and cranium are composed of cartilage and have never been found to petrify in Edestoid sharks. The only remains that are found are teeth and scales from the skin.
Drawing borrowed from: Handbook of Paleoichthyology Volume 3A, Chondrichthyes 1
by R. Zangler ( 1981 )