Relative chronological (stratigraphic) ordering of major evolutionary first-appearance events requires knowledge of the approximate geological periods in which each major vertebrate/plant group first arose: fishes are the oldest of the listed groups (earliest Paleozoic, Ordovician-Silurian), followed much later by mammals (Late Triassic), then birds (Late Jurassic), and finally flowering (angiosperm) plants, which are the youngest of the four (Early Cretaceous).