What is "edestidae"

Edestidae is a poorly known, extinct family of shark-like eugeneodontid holocephalid cartilaginous fish. Similar to the related family of Helicoprionidae, members of this family possessed a unique "tooth-whorl" on the symphysis of the lower jaw as well as pectoral fins supported by long radials. In addition to having a tooth-whorl on the lower jaw, at least species of the genus Edestus had a second tooth-whorl in the upper jaw. The palatoquadrate was either fused to the skull or reduced. Edestids, along with the rest of Eugeneodontida, are placed within Holocephali.