premise: They admit that both the vegetable and the animal species have changed, for in some of the strata of the earth they have discovered plants which existed in the past and are now extinct;
hypothesis: Environmental changes is most responsible for the extinction of most species of plants and animals that have lived on earth.
hypothesis_graph_structure: Environmental changes<>is<>most responsible for the extinction of most species of plants and animals$$$plants and animals<>have lived<>on earth