Life timeline view • discuss • -4500 — – -4000 — – -3500 — – -3000 — – -2500 — – -2000 — – -1500 — – -1000 — – -500 — – 0 — water Single-celled life photosynthesis Eukaryotes Multicellular life Land life Dinosaurs Mammals Flowers ← Earliest Earth (−4540) ← Earliest water ← Earliest life (−4100) ← LHB meteorites ← Earliest oxygen ← Atmospheric oxygen ← Oxygen Crisis ← Earliest sexual reproduction ← Cambrian explosion ← Earliest humans P h a n e r o z o i c P r o t e r o z o i c A r c h e a n H a d e a n Axis scale: millions of years. Also see: Human timeline and Nature timeline