I am reading up on the evolution of insects, and insects supposedly evolved on land rather than water. How do people know?What evidence is there that insects evolved on land and not water?
The sister group of hexapods (Insects plus Collembola, Protura, and Diplura) are thought to be Remipedes. Remipedes are cave-dwelling aquatic pancrustaceans. The most recent common ancestor of Hexapoda and Remipedia was likely aquatic. But somewhere along the pathway to becoming modern hexapods, after they split from the lineage leading to modern remipedes, the ancestors of modern hexapods developed tracheal respiratory systems that function on land. So the evidence comes from the fact that the extant lineages of insects, close to their most recent common ancestor, including Collembola, Protura, Diplura, Archeaognatha, and Zygentoma are all terrestrial.