The document outlines the geologic time scale, beginning with the earliest eons of Hadean and Archean in the Precambrian era. It then discusses the major periods within the Phanerozoic eon, including the Paleozoic era marked by diversification of marine life and early plants and amphibians, the Mesozoic era when reptiles like dinosaurs dominated, and the Cenozoic era when mammals appeared and human evolution began.

1. Geologic Time Scale
GENERAL BIOLOGY
T-TH 10:00-11:00

2. Geologic Time Scale
 Eon
 Era
 Period

4. Pre Cambrian
 Hadean
 Archean
 Proterozooic

5. Hadean eon
 Chaotic event
 800 m.y.a.
 Hades-Hell
 Earth is continuously bombarded by Meteorites
 Severe volcanism
 Oceans were formed
 Earth’s core and crust stabilized

6. Archean eon
 Most of the Earth were covered with ocean
 Continents formed
 Earth was warm
 Little or no Oxygen

7. Proterozoic eon
 1.9 billion years
 Longest eon
 Great changes occurred
 Oxygenation of Atmosphere
 Origin and Diversification of Eukaryotic organisms
 Multicellular organisms developed

8. Phanerozoic Eon
 Paleozoic era
 Mesozoic era
 Caenozoic era

9. Paleozoic era
EARLY PALEOZOIC
 Diversity of life
 Fossilized Trilobites and Brachiopods flourished
 Marine life and some invertebrates flourished in shallow waters

10. MIDDLE PALEOZOIC
 Marine organisms developed shells
 First amphibians appeared (Devonian period)
 Terrestrial or Land plants appeared
 Giant Ferns and marsh plants flourished
 Clams and snails flourished
 Fishes, highly diversified

11. LATE PALEOZOIC
First reptiles appeared
 First Reptiles appeared
 Terrestrial climate changed
 Plants grew to enormous size and eventually formed huge deposits

12. Mesozoic era
Triassic Period
 Formation of several continents
 N. America began to part from Europe
 S. America and Africa began to drift apart
 Australia,India and New Zealand had all left Africa and Arabia
 Dinosaurs first appeared
 Descendants of primitive reptiles
 Ancestors of the early birds
 The Triassic ranges roughly from 252 million to 201 million years ago

13. Jurassic Period
 The Jurassic ranges from 200 million years to 145 million years ago
 The first true crocodiles evolved, pushing the large amphibians to near extinction
 During this epoch, dinosaurs flourished as huge herds of sauropods, such
as Brachiosaurus and Diplodocus, filled the fern prairies, chased by many new predators such
as Allosaurus.

14. Cretaceous Period
 The Cretaceous is the longest period of the Mesozoic
 The Early Cretaceous spans from 145 to 100 million years ago
 Other dinosaurs rose up to fill the empty space that the Jurassic-Cretaceous
extinction left behind, such as Carcharodontosaurus and Spinosaurus.
 The Late Cretaceous featured a cooling trend that would continue in
the Cenozoic Era.
 Tyrannosaurus, Ankylosaurus, Triceratops and hadrosaurs dominated the food
web.

15. Cenozoic era
 Mountains were uplifted
 Mammals appeared
 Volcanic activity flows much lava and basalt rocks
 Warm blooded animals flourished
 End of Cenozoic started the Glacial age
 Humans started to evolve

16. Thank You