Chondrichthyan spines and dermal denticles are reported from the Middle Pennsylvanian Minturn Formation, Eagle County, Colorado. The most common element is a dorsal finspine referred to Ctenacanthus buttersiSt. John and Worthen, 1883. Some of the specimens are more complete distally than the holotype and only previously figured specimen of C. buttersi. Less common remains include a dorsal finspine referred to Acondylacanthus nuperusSt. John and Worthen, 1883, a smooth-ribbed dorsal finspine close to “CtenacanthusfuricarinatusNewberry, 1875, a spine fragment probably referrable to Physonemus sp., and two large-noded dorsal finspines probably referrable to two different species of Bythiacanthus. Dermal denticles are referred to Petrodus patelliformisM'Coy, 1848. Ctenacanthus buttersi finspines and some large cladodont teeth, referred to “Symmoriumoccidentalis(Leidy), 1859, may belong to the same species. This conjecture is based mainly on the relative abundances of chondrichthyan teeth found at the same locality.

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