-
200
Earth was formed 4.6 billion yrs ago.
Earth was formed 4.6 billion years ago. -
200
Rocks were formed 4 billion yrs ago.
Earth cooled and solid rocks formed on its surface. -
200
Water was on Earth 3.8 billion yrs ago.
Earth's surface cooled enough for water to remain a liquid, and oceans covered much of the surface. -
300
Photosynthetic bacteria pump oxygen.
Photosynthetic bacteria began to pump oxygen. -
400
Precambrian: 650-544 million yrs ago.
Vendian period. Life first began. -
500
Paleozoic Era: 544 million yrs ago.
Many vertebrates and invertebrates lived during this time. Cambrian period: 544-505 millions of yrs ago. Invertebrates, brachiopods, trilobites. Ordovician period: 505-440 millions of yrs ago. Silurian period: 440-410 million of yrs ago. Arthropods became 1st land animals. First vertebrates appeared. First land plants evolved from aquatic ancestors. Carboniferous period: 360-290 millions of yrs ago. Devonian period: 410-360 millions of yrs ago. Permian period: 290-245 millions of yrs ago. -
500
Devonian Period: Age of fish
Some plants adapted to drier areas and invaded more habitats. Insects appeared on land. Most fishes had jaws, bony skeletons, and scales. -
Feb 1, 600
Mesozoic Era: 245 million years ago
Dinosaurs lived during this time. Mammals began to evolve during this era. Triassic period: 245-208 millions of years ago. Jurassic period: 208-145 millions of years ago. Cretaceous period: 145-65 millions of years ago. -
Apr 11, 700
Cenozoic Era: 65 million yrs ago-present
Mammals became common during the Cenozoic. Tertiary period: 65-1.8 millions of years ago. Quaternary period: 1.8-present -
Period: Apr 11, 700 to
Cenozoic Era
-
Age of Reptiles: Mesozoic
Triassic: fishes, insects, reptiles, and cone-bearing plants. Jurassic: Birds. Cretaceous: Reptiles, birds, turtles, crocodiles, fishes, and marine invertebrates. Leafy trees, shrubs, and small flowering plants. -
Age of Mammals: Cenozoic
Tertiary: climate was warm and mild. Marine mammals; whales and dolphins evolved. Grasses evolved, providing food for grazing mammals.Some mammals became very large, as did some birds. Quaternary Period: Earth’s climate cooled, causing a series of ice ages. About 20,000 years ago, Earth’s climate began to warm and sea levels began to rise. In the oceans, algae, coral, mollusks, fishes, and mammals thrived.Insects, birds, and land mammals were common
