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(5 BYA) No Earth yet
Our solar system and earth was a swirling mass of gas, dust, and debris. -
(4.6 BYA) Earth Grew Larger
Earth grew larger as gravity pulled in more debris -
(4 BYA) Earth is Formed
Earth became formally formed. Period of recorded history began. -
(4 BYA) First Cells
The first cells were anaerobic, heterotrophic prokaryotes -
(3.5 BYA) Fossils
Fossils of stromatolites as old as 3.5 billion years old are known. -
(3 BYA) Life Forms
Some forms of life had become photosynthetic. -
(2.2 BYA) Same Earth
Earth appeared the same as it does today. -
O2 Levels
O2 levels reached today's levels -
(1.5 BYA) Endosymbiosis
A type of small aerobic prokaryote was engulfedby and began to live and reproduce inside of a larger, anaerobic prokaryote. This theory is called endosymbiosis. -
(1 BYA) Ozone (O3) formed
protected organisms from harmful UV rays so they could exist on land -
(1600-1700) Redi's experiment
Prooved that flies come only from eggs laid by other flies; disprooved spontaneous generation theory -
(1600-1700) First microscope
Revealed the world is filled with tiny creatures -
(1700-1800) Spallanzani's experiment
designed experiment to test the hypothesis of spontaneous generation of microorganisms -
(1800-1900) Pasteur's Experiment
Set up experiment that settled issue of spontaneous generation and prooved it wrong. -
(1900-present) Thomas Cech
early 1980's found that a type of RNA found in some unicellular eukaryotes is able to act as a chemical catalyst. -
(1900-present) Lynn Margulis
proposed that early prokaryotic cells may have developed a mutually beneficial relationship -
(1900-present) Urey and Miller
Set up experiments that produced a variety of compounds, including amino acids. -
(1900-present) Radioactive Dating
method to establish age of materials -
(1900-present) Oparin's hypothesis
It is that organic compounds undergo reactions leading to more complex molecules- evenually leading to first life forms. Used in Urey & Miller's experiment -
(1900-present) Fox
did extensive research on the physical structures that may have given rise to the first cells
