Petalodontiformes

200px|thumb|left|Teeth of Petalodus|Petalodus ohioensis Petalodontiformes ("thin-plate teeth") is an extinct order of marine cartilaginous fish related to modern day chimaera found in what is now the United States of America and Europe.

thumb|left|Teeth of Janassa Janassa is an extinct genus of petalodont cartilaginous fish that lived in marine environments in what is now central United States of America and Europe during the Carboniferous and upper Permian.

Belantsea (named after a legendary ancestor of the Crow Tribe) is a genus of extinct petalodontiform cartilaginous fish that lived during the Early Carboniferous. Fossils of Belantsea montana have been found in the Bear Gulch Limestone lagerstätte, and are preserved in exceptional detail. Its body was tall and compressed, with large pectoral fins and a small tail fin. This body plan suggests a lifestyle similar to modern reef fish, and it is thought that Belantsea was adapted for life in reefs of sponges. Its few, large, triangular teeth suggest a diet of hard-shelled marine invertebrates. The

Petalodontidae is an extinct family of marine cartilaginous fish related to the modern-day chimaeras, found in what is now the United States of America and Europe. With a very few exceptions, they are known entirely from teeth. All fossils range from the Carboniferous to the Permian, where they are presumed to have died out during the Permian/Triassic extinction event.