Alopiidae
Alopiidae is a family of large mackerel sharks. The only extant genus is the thresher shark. The extinct genera Anotodus, Paranomotodon, and Trigonotodus have been proposed as members of this family.
It is believed that thresher sharks originated from a common ancestor that appeared in the Late Cretaceous, at least. The first thresher sharks of the genus Alopias appeared about. Trigonotodus is known from the Oligocene.