The Indian Cave Sandstone (Upper Pennsylvanian, Gzhelian) from the area of Peru, Nebraska, USA, has yielded

numerous isolated chondrichthyan remains and among them teeth and dermal denticles of the Symmoriiformes

Zangerl, 1981. Two tooth-based taxa were identified: a falcatid Denaea saltsmani Ginter and Hansen, 2010,

and a new species of Stethacanthus Newberry, 1889, S. concavus sp. nov. In addition, there occur a few long,

monocuspid tooth-like denticles, similar to those observed in Cobelodus Zangerl, 1973, probably representing

the head cover or the spine-brush complex. A review of the available information on the fossil record of

Symmoriiformes has revealed that the group existed from the Late Devonian (Famennian) till the end of the

Middle Permian (Capitanian).