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proto-Atlantic
proto-Atlantic n.
Brit. 
/ˌprəʊtəʊətˈlantɪk/
, /ˌprəʊtəʊətˈlantɪk/U.S. /ˌproʊdoʊətˈlæn(t)ɪk/
Geography (more fully proto-Atlantic Ocean) the Atlantic Ocean at an early stage of its development./ˌproʊdoʊətˈlæn(t)ɪk/ΘΚΠ
the world > the earth > water > sea or ocean > specific seas > [adjective] > Atlantic Ocean > Proto-Atlantic
proto-Atlantic1966
1966 J. T. Wilson in Nature 13 Aug. 676/1 It is proposed that, in Lower Palaeozoic time, a proto-Atlantic Ocean existed so as to form the boundary between the two realms, and that during Middle and Upper Palaeozoic time the ocean closed by stages.
1972 Sci. Amer. Nov. 62/3 In Devonian times an order of jawless freshwater fishes, cousins to the orders that once flourished on opposite sides of the proto-Atlantic, inhabited the streams of the region that is now the European and Asiatic flanks of the Urals.
1994 New Scientist 22 Oct. 10/3 During the Middle Jurassic, the Iberian peninsula was on the shores of a proto-Atlantic, and was a close neighbour of Britain and Canada.
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