A new janassid petalodont chondrichthyan from the Early Carboniferous of Derbyshire, UK

The very small teeth of a new petalodont chondrichthyan are described from the Lower Carboniferous Eyam Limestone Formation (Peak Limestone Group, Carboniferous Limestone Supergroup; Brigantian, Early Carboniferous) of Derbyshire. Cypripediodens cristatus gen. et sp. nov. belongs to the Family Janassidae on the basis of the angle formed between the base and the crown. Presumed lower symphyseal teeth are Fissodus-like, possessing two labial cusps, whilst the rest of the dentition is relatively homodont. Individual crowns measure up to 1.3 mm labiolingually and possess a single labial cusp with virtually circular cross-section, separated from a prominent lingual cusp with circumferential cristae from which it is separated by a central trough.