coho, freshwater sockeye and Atlantic salmon have been established in Patagonia, as well. † Both the Salmo and Oncorhynchus genera also contain a number of species referred to as trout. Within Salmo, additional minor taxa have been called salmon in English, i.e. the Adriatic salmon (Salmo obtusirostris) and Black Sea salmon (Salmo labrax). The steelhead anadromous form of the rainbow trout migrates to sea, but it is not termed "salmon". Also, there are several other species which are not true salmon, as in the above list but have common names which refer to them as being salmon. Of those listed below, the Danube salmon or huchen is a large freshwater salmonid related to the salmon above, but others are marine fishes of the unrelated Perciformes order: Eosalmo driftwoodensis, the oldest known Salmoninae fish in the fossil record, helps scientists figure how the different species of salmon diverged from a common ancestor. The British Columbian salmon fossil provides evidence that the divergence between Pacific and Atlantic salmon had not yet occurred 40 million years ago. Both the fossil record and analysis of mitochondrial DNA suggest the divergence occurred 10 to 20 million years ago. This independent evidence from DNA analysis and the fossil record indicate that salmon divergence occurred long before the glaciers (of Quaternary glaciation) began their cycle of advance and retreat. Distribution Atlantic salmon (Salmo salar) reproduce in northern rivers on both coasts of the Atlantic Ocean. Landlocked salmon (Salmo salar m. sebago) live in a number of lakes in eastern North America and in Northern Europe, for instance in lakes Sebago, Onega, Ladoga, Saimaa, Vänern, and Winnipesaukee. They are not a different species from the Atlantic salmon but have independently evolved a non-migratory life cycle, which they maintain even when they could access the ocean. Chinook salmon (Oncorhynchus tshawytscha) are also known in the United States as king salmon or blackmouth salmon, and as spring salmon in British Columbia. Chinooks are the largest of all Pacific salmon, frequently exceeding . The name tyee is used in British Columbia to refer to Chinook over 30 pounds, and in the Columbia River watershed, especially large Chinooks were once referred to as June hogs. Chinook salmon are known to range as far north as the Mackenzie River and Kugluktuk in the central Canadian arctic, and as far south as the Central California coast. Chum salmon (Oncorhynchus keta) is known as dog,