Change: Deep Time

1. Atmosphere forms: Precambrian Eon; Hadean 4,500 mya

2. Earth's core forms: Precambrian Eon; Hadean 4,400 mya

3. First living organisms evolve(prokaryotic cells): Precambrian Eon; Hadean 3,850 mya

4.First eukaryotic cells evolve: Precambrian Eon; Archaean 2,700 mya

5. First multicellular organisms evolve(algae): Precambrian Eon; Proterozoic 1,200 mya

6. Ozone layer forms: Precambrian Eon; Proterozoic 600 mya

7. First Chordates evolve: Paleozoic Era; Cambrian 535 mya
A chordate are any of the numerous animals belonging to the the family Chordata having at some stage of development a dorsal nerve cord.

8. First land plants evolve: Paleozoic Era; Ordovician 480 mya

9. First land animals (bugs) evolve: Paleozoic Era; Carboniferons 420 mya

10. First land vertebrates evolve: Paleozoic Era; Devonian 375 mya
A vertebrate is an animal having a backbone or spinal column.

11. First flowering plants evolved: Paleozoic Era; Devonian 360 mya

12. First reptiles evolve: Paleozoic Era; Permian 275 mya

13. Pangaea forms: Paleozoic Era; Permian 280 mya
The Pangaea is a theory that states that all present continents were once together and collectively known as a "supercontinent" called Pangaea.

14. First mammals evolve: Mesozoic Era; Triassic 220 mya

15. First birds evolv: Mesozoic Era; Jurassic 150 mya

16. First primates evolve: Cenozoic Era; Paleocene 60mya

17. Continents reach their present-day formation: Cenozoic Era; Eocene 40mya

18. First apes evolve from the primate lineage: Cenozoic Era; Oligocene 25 mya

19. Hominids evolve from the ape lineage: Cenozoic Era; Pliocene 5.2 mya
A hominid is any member of the biological primate family Hominidae.

20. First early humans evolve from the hominid lineage: Cenozoic Era; Pleistocene 0.16 mya

21. Modern humans evolve from the human lineage: Cenozoic Era; Pleistocene 0.1 mya