Xenacanthidae is a family of prehistoric

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...

s in the order

Xenacanthida Xenacanthida (or Xenacanthiforms) is a super-order of extinct shark-like elasmobranchs that appeared during the Lower Carboniferous period. The order includes the families Xenacanthidae, Sphenacanthidae, Diplodoselachidae, and Orthacanthidae. ...

.Ginter, M., Hampe, O., Duffin, C., 2010.Handbook of Paleoichthyology Volume 3D: Chondrichthyes: Paleozoic Elasmobranchii: Teeth. ''in'' Schultze, H. (ed.) Handbook of Paleoichthyology. Verlag Dr. Friedrich Pfeil, München

References

Carboniferous sharks Permian sharks Triassic sharks Prehistoric cartilaginous fish families Carboniferous first appearances Triassic extinctions {{paleo-shark-stub