Squatinactis montanus has the teeth, jaws and skull of a cladodont-toothed shark. Its body resembles that of the modern skates, rays, or angel sharks in being dorsoventrally flattened and having its pectoral fins greatly extended to the sides. S. montanus probably used the wing-like pectoral fins as well as the whip tail for propulsion. This body design has recurred several times in the fossil record for bottom-living lurking predators. They ranged in size to 2 feet.
There are a few placoid scales on the snout and flanks; but Squatinactis is otherwise smooth-skinned. The spine on top of the tail, as in modern stingrays, is a dorsal fin spine.
There was a blunt snout, a terminal mouth, large jaws, and long sharp cladodont teeth.
- Lund, R. 1988. "New information on Squatinactis caudispinatus (Chondrichthyes, Cladodontida) from the Chesterian Bear Gulch Limestone of Montana." J. Vert. Paleo., 8:340-342.
- Lund, R., and R. Zangerl, 1974. "Squatinactis caudispinatus, a new elasmobranch from the Upper Mississippian of Montana." Ann. Carnegie Mus. 45: 43-54.