Black dogfish to the clade formed by the granular dogfish ("C. granulatum") and combtooth dogfish ("C. nigrum"). The black dogfish is a common species, with a wide but discontinuous distribution in the temperate waters of the Atlantic Ocean; its range abuts, but does not extend into, the Arctic Ocean. In the northeast, it occurs from Iceland to Sierra Leone, including the Faroe Islands, southern Norway, and the Rockall Trough and Porcupine Seabight off Ireland. In the northwest, it is found from southern Greenland and Baffin Island to Virginia, being particularly abundant in the Laurentian Channel, and may occur further south to the
Benue Trough period is also found only in the south of the trough, and may be related to an isostatic response to the earlier crustal thinning. The mantle plume activity was probably limited in its effect, with most of the basins in the trough being created from a combination of extension and strike-slip faults. The faults extend into the ocean with the Chain and Charcot fault zones, and have their counterparts in northeastern Brazil. Nigeria is rich in coal deposits derived from terrestrial organic matter, most of which lie in the Benue Trough. These are mined in Enugu State. The Enugu deposits