Description

Harpacodus dentatus
Upper Mississippian
Indian Springs Formation
Crawford County, Indiana, USA

Beautiful 8mm petalodont shark tooth on 22mm matrix. Very rare.

A petalodont shark is an extinct type of cartilaginous fish that belonged to the subclass Holocephali, which includes modern chimaeras. These fascinating creatures lived from the Late Devonian to the Early Permian period (roughly 359–299 million years ago). They are part of the order Petalodontiformes and are recognized for their distinctive teeth, which resembled flower petals—hence their name.
Key Features:

Petal-shaped Teeth:
Petalodont sharks had broad, flat, and petal-like teeth. These were well-suited for crushing and grinding hard-shelled prey such as mollusks and crustaceans.

Cartilaginous Skeletons:
Like modern sharks and rays, petalodonts had skeletons made of cartilage rather than bone, which limited their fossil preservation primarily to teeth and jaw fragments.

Body Shape:
Although complete fossils are rare, it’s believed that petalodonts had streamlined, shark-like bodies, similar to other cartilaginous fish of their time.

Habitat:
These animals likely lived in shallow marine environments, where they could find an abundance of shelled prey.