Premise: A Grand Griffon Vendéen is a breed of hunting dog originating in France. It existed as early as the 16th Century, and was the first of the Vendée griffons to be bred. It is a descendant of the Canis Segusius used by the Gauls, through the so-called King's whites and the Griffon Fauve de Bretagne, which is also an ancestor of the Basset Fauve de Bretagne.
Hypothesis: The Grand Griffon Vendeen and Basset Fauve de Bretagne share an ancestor.