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
Rockall Basin 55 million years ago, a continental fragment formed between Greenland and Europe when the ancient continent of Laurasia was split apart by plate tectonics. The Rockall Islet is the highest point of the plateau, rising 21 m above sealevel. It is made of a type of peralkaline granite. The petroleum and natural gas resources in the area have been the source of political tensions between the governments of the United Kingdom, Ireland, Iceland and the Faroe Islands (a possession of Denmark). The area supports cold water coral colonies and carbonate mound fields such as the Logachev Mounds; the trough supports