As can be learned from fossils—our source of information regarding the natural history of species that once existed in the past—living things possessed of complete features have always populated the Earth. The feet, forearms, wings, skins, fur, lungs, skulls, vertebrae, bone structures and countless other such characteristics of these creatures have always been fully formed, unique to them and of an ideal structure. No intermediate stage—in other words no "developing" limb or organ—exists in any fossil. This represents a major impasse for evolutionists. The 45-million-year-old fungus gnat fossil pictured is one proof of these facts.