Cardipeltis bryanti Denison, 1966 fossil fish from the Devonian of Wyoming, USA (public display, FMNH PF 3895, Field Museum of Natural History, Chicago, Illinois, USA).

This fossil jawless fish from the Lower Devonian Beartooth Butte Formation, from an outcrop in the western flank of the Bighorn Mountains, northern Wyoming, USA. Cardipeltis is an agnathan fish with a bony exoskeleton. Agnathans are jawless, and represent the oldest-known, ancestral fish group. Agnathans are still alive today - they include the hagfish. Early agnathans with bony exoskeletons are often called ostracoderms. The fossil shown here is a rare, articulated specimens of Cardipeltis - the ventral (underside) surface is exposed. The elongated structure at the bottom of the specimen is the tail. Cardipeltis has a dorso-ventrally compressed body, consistent with a benthic swimming lifestyle.