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Evolution: History of Life on Earth
Transcript of Evolution: History of Life on Earth
The Age of the Earth
Mesozoic and Cenozoic Eras
Earth formed 4.5 billion years ago
Evidence of Earth's age, history of life, and evolution:
FOSSILS: can be
ineralized or preserved in amber
similar characteristics in 2 or more species
layers of sediment and rocks paint a
picture of the past
The age of the Earth is divided into 4 chunks or time, or eras. Each era ended with a
Geologic Time Scale
Earth is newly formed.
The planet is being bombarded with meteors and asteroids, some of which may have brought in the first molecules necessary for life.
Other theories of how life first began involve energy from hydrothermal vents allowing formation of earliest molecules.
Earliest organisms likely had only RNA for genetic material.
Cyanobacteria begin photosynthesizing and producing oxygen, which changes the atmosphere.
1st land plants
Paleozoic Era: evolution leads to many new species
Mesozoic: Reptiles, birds, dinosaurs, flowering plants
Cenozoic: mammals become dominant life form on land;
human's early ancestors (homonids)
1. Precambrian: 4.5 billion to 542 million years ago (mya)
2. Paleozoic: 542 mya to 252 mya
3. Mesozoic: 252 mya to 66 mya
4. Cenozoic: 66 mya to present
prokaryotes and early eukaryotes
multicellular (organisms with more than one cell) such as protists
Wider variety of marine invertebrates
1st land animals
These 2 eras are separated by the K-T mass extinction when dinosaurs, 50% of other species, and 90% of plankton went extinct.
This Prezi does not even begin to cover
everything that has happened during
the history of the Earth!
However, you now know the major divisions of time and the general order of evolution for the major kingdoms and families of organisms that are living, or have lived, on the Earth.
Events during Precambrian
4.5 billion to 542 million years ago (mya)
542 mya to 252 mya
252 mya to 66 mya 66 mya to present
How old is the earth?
When did dinosaurs “show up”? Flowers? Humans? Amphibians? In what order could these organisms be found on the planet?
You will be making a timeline of Earth’s history.
The timeline should be done to scale. A scaled representation requires that 10 cm on your timeline represent the same amount of time anywhere along the timeline. To do this you will:
Measure out a strip of adding machine tape 5 meters long. A meter stick will be provided in lab.
Each meter will represent 1 billion years.
Select one end of the tape to represent the Present. Beginning at that end, mark off each billion years (1 billion, 2 billion, etc.)
Starting with the oldest event (Event #1), mark off all of the important events in Earth’s history shown on your handout. In each case you should write the date and event directly on the timeline. If you have time, you can add drawings and color them.
1 meter = 1 billion years of time
1 decimeter = 100 million years
1 centimeter = 10 million years
1 millimeter = 1 million years
What is speciation?
What causes speciation?
How long does it take to occur?
(stop video at 4 minutes)
Speciation resulted in the great variety of life forms on the planet today. This has taken an incredibly long time to happen ... billions of years, in fact.