1. Geologic Time Scale

2. Time Periods
Eons
Eras
Periods
Epochs

4. Precambrian Era Time Period: 4.54 billion to 544 million years ago
Earth formed from planetary nebula
Organisms:
First cells ( 3.9 bya)
Blue-green algae & stromatolites (3.6 bya)
Oldest fossilized bacteria (3.25 bya)
Oldest fossilized cells w/ nucleus (2.1 bya)
First multi-celled organisms (1.5 bya)
First marine worms & jellyfish (670 mya)

5. Paleozoic Era: Cambrian Period
Time Period: begins 544 million years ago
Organisms:
Burgess Shale
First animals with hard
parts (trilobites)

6. Paleozoic Era: Ordovician Period
Time Period: began 505 million years ago
Organisms:
First fish
First fossil evidence of land plants

7. Paleozoic Era: Silurian Period
Time Period: Began 438 million years ago
Organisms:
First vascular land plants
Oldest lung fish fossils

8. Paleozoic Era: Devonian Period
Time Period: Began 408 million years ago
Organisms:
Oldest fossil evidence of mosses (408 mya)
First insects (beetles), scorpions, and centipedes (385 mya)
First lobe-finned fish (380 mya)
First land animals (amphibians) (375 mya)
First sharks (370 mya)
First seed plants (ferns) (365 mya)

9. Paleozoic Era: Mississippian Period
Time Period : Began 360 million years ago
Organisms:
First possible reptiles (330 mya)

10. Paleozoic Era: Pennsylvanian Period
Time Period: Began 320 million years ago

11. Paleozoic Era: Permian Period
Time Period: Began 286 million years ago
Organisms:
Sail-backed reptiles
End of Paleozoic– 96% of all life on Earth perishes

12. Mesozoic Era: Triassic Period
Time Period: Began 245 million years ago
Organisms:
First crocodiles (240 mya)
First dinosaurs (228 mya)
Eoraptor and Saltoposuchus
First mammals (shrew-like) (221 mya)
First turtles (210 mya)

13. Mesozoic Era: Jurassic Period
Time Period: Began 208 million years ago
Organisms:
Dilophosaurus (195 mya)
First bird- Archeopteryx
(155 mya)
Apatosaurus and Brachiosaurus (152 mya)
Allosaurus (carnivore) (150 mya)
Stegosaurus (plate-backed dinosaur) (148 mya)

14. Mesozoic Era Cretaceous Period
Time Period: Began 144 million years ago
Organisms:
First flowering plant (115 mya)
Duck-billed dinosaurs (82 mya)
Protoceratops (first dinosaur eggs discovered) (80 mya)
Triceratops (75 mya)
Tyrannosaurus rex & Velociraptor (70 mya)
Ended Mesozoic with meteorite

15. End of Mesozoic Era

16. Cenozoic Era Tertiary Period
Time Period: Began 65 million years ago
Organisms:
First ancestors of dogs & cats (64 mya)
Grasses become widespread (60 mya)
First ancestors of pigs & deer (57 mya)
First horses (Eohippus) (55 mya)
First ancestors of rabbits (45 mya)
First monkeys (39 mya)
Oldest human like ancestors (hominids) (4 mya)

17. Cenozoic Era Quaternary Period
Time Period: Began 2 million years ago
1st of 4 ice ages (1 mya)
Organisms:
Oldest direct human-ancestor fossil
Homo habilis (1 mya)
First modern man, Homo sapiens (0.1 mya)
Mammoth & mastodon bones (0.05 mya)