Article: Neoselachian sharks' teeth from the Lower Carboniferous of Britain and the Lower Permian of the U.S.A.

Isolated leeth of Anachronistes fordi gen. et sp. nov. are recorded from the Upper Carboniferous Limestone, Lower Carboniferous of Derbyshire, England, and Clwyd, North Wales. The teeth are assigned to the Family Anachronistidae fam. nov. of uncertain position within the neosclachiun sharks. A further unnamed tooth belonging to the genus is recorded from the Lower Permian of Nevada, U.S.A. The teeth of Anachronistes are neosclachian since they possess a conical central cusp, well-developed lateral blades and basal flange, V-shaped basal root face and hemiaulacorhize vascularization. The teeth of Anachronistic lack enameloid. The teeth are most closely comparable to those of Squatina and Orectolobus, and belong to a bottom feeder. The teeth extend the record of the neosclachian sharks from the Lower Norian (Upper Triassic) back into the Dinantian (Lower Carboniferous). Two types of monognathic gradient heterodonty are distinguished; linear gradient helerodonty in which there is gradual reduction in coronal profile commissurally; and non-linear gradient heterodonty, where coronal profile reduction occurs both mesially and distally from a central high tooth row.