Download - Earth History - The Geologic Time Scale. The Age of the Earth 4.6 billion years old = 4,600,000,000
Earth History -The Geologic Time Scale
The Age of the Earth4.6 billion years
old =4,600,000,000
The earth’s 4.6 billion year history is divided
into major units of time:
Cenozoic Era
Mesozoic Era
Paleozoic Era
Precambrian Time
Precambrian Time• 4.6 billion years before present
to 544 million years before present
• Longest era with a sparse fossil record
• Origin of earth’s crust, first atmosphere, and first seas
• Earliest fossils of cyanobacteria use photosynthesis to produce oxygen
• Ozone layer in the atmosphere is formed from oxygen
Paleozoic era
• 544 million years before present to 245 million years before present
• Marine communities flourish
• Early fishes develop
• Origin of amphibians, insects & reptiles
• Recurring ice ages/ Appalachians mountains form
• Spore-bearing plants dominate
.
Paleozoic era (continued)…
• 286 - 248 million years before present: Supercontinent of Pangea forms
• 248 million years before present: MASS EXTINCTION-90 % of all known families lost!
.
c
Mesozoic Era
• 245 million years before present - 65 million years before present
• The age of the dinosaurs!
• Gymnosperms dominate land plant/ origin of angiosperms - flowering plants
• Origin of mammals & birds
• 145 million years before present - asteroid impact? MASS EXTINCTION
• Pangea begins to separate/ Rocky mountains form
65 million years before present….
• ASTEROID IMPACT!
• Mass extinction of ALL dinosaurs and many marine organisms
• End of the Mesozoic era
.
Cenozoic Era
• 65 million years before present -today
• Present era we live in
• Continued evolution and adaptations of flowering plants, insects, birds, mammals
• Mammals dominant
• Major crustal movements & mountain building (Alps & Himalayan mountains form)
.
And during the Cenozoic era…
• The most primitive hominid (human ancestor) evolves - approximately 4.4million years before present
• The first modern humans (homo sapiens) evolved approximately 100,000 years before present
Image courtesy of: http://www.wilderdom.com/images/evolution/8.jpg
Assignment – You can use your Textbook and your cell Phones
• Describe the Experiments of Louis Pasteur and Alexander Oparin and Stanley Miller in relation to Formation of First Cells on Earth.
• Bacteria were the first living cells on earth. How did Eukaryotic or Multicellular organisms came into being. Describe Endosymbiosis.