FC03.txt

• Oldest rocks are > 4 billion years old.
• Surface waters stabilized into oceans.
• Surface and atmosphere had N₂, CO₂, HCN, N₃, and H₂O, but little O₂.
• O₂ is destructive to bonds in organic molecules.
• The young sun gave off less energy than now.
• Earth's climate was cold.

• The fossil records reveals changes in the history of life on earth.
• Sedimentary rocks are deposited into strata and are rich sources of fossils.
• Few individuals have fossilized, and even fewer have been discovered.

• Species that are most likely to of fossilized must have:
• Existed for a long time
• Were abundant and widespread
• Had hard body parts

Reveals the relative ages of fossils.

• Determines the absolute age.
• Parent isotope decays to Daughter isotope at a constant rate.
• Each isotope has a known half-life.

For older fossils, date sedimentary rock layers above and below the fossil.

The sedimentary rocks are debris from upstream which predate the fossil.

• Can provide dating information.
• Reversals of the magnetic poles leave their record on rocks.

Correspond to extinction events in the fossil record.

• May have begun earlier; even before the atmosphere stabilized
• May have been destroyed several times.
• Did not use to transform energy.
• May have released methane (CH₄).

May have warmed the climate via the greenhouse effect.

The warming of the atmosphere by energy(heat) that entered via sunlight and cannot escape due to some sort of barrier(CH₄).

• Oldest known fossils were stromatolites.
• Rock-like structures composed of many layers of bacteria and sediment.

Earth's sole inhabitants from 3.5 to about 2.1 billion years ago.

• Probably from cyanobacteria.
• Added oxygen(O₂) to the atmosphere and water.
• Most atmospheric O₂ is of biological origin.

• Rising O₂ levels poisoned many kinds of early life.
• Other bacteria began using O₂ in their metabolism.
• O₂ reacted with dissolved iron and precipitated out to form banded iron formations.

• Evolution of eukaryotic cells allowed for a greater range of unicellular forms.
• Eukaryotes: true nucleus, membrane bound organelles, bigger(more complex) than Prokaryotes

• Diversification occurred when multicellularity evolved.
• Gave rise to algae, plants, fungi, and animals.
• The oldest known fossils are small algae.

• Sudden appearance of fossils resembling modern phyla.
• Provides the first evidence of predator-prey interactions.
• More complex interactions between species.
• Atmospheric oxygen levels increasing.
• Had a long fuse.

• Mobility allows for more interactions(predator/prey)
• More oxygen = can disperse easily
• Evolution from predator/prey scenario
• Presence of hardy body increased (more fossils)

• Plants and fungi likely colonized land together.
• Arthropods and tetrapods are the most widespread and diverse land animals.
• Tetrapods evolved from lobe-finned fish.

• Most species that have ever lived are now extinct.
• Rate of extinction has increased dramatically and caused a mass extinction periodically.
• In each mass extinction events, more than 50% of Earth's species became extinct.

At the end/start of a period

• Alter ecological communities and the niches.
• Takes 5 to 100 MY for diversity to recover.
• Can pave way for adaptive radiations.

Evolution of diversely adapted species from common ancestor upon a new environmental opportunity.

• Continents move slowly through the process of continental drift.
• The supercontinent is called Pangaea.

• Forces life to adjust to changing environments.
• Previously attached continents may share similar species.

• Life began synthetically (chemicals).
• Life continues from pre-existing life (natural).
• Louis Pasteur experiments.

• Abiotic synthesis of monomers.
• Monomers joining together to form macromolecules.
• Origin of self- replicating molecules (enabling inheritance).
• Packaging into membrane-enclosed protobionts.

• Tried to recreate the conditions of early Earth.
• Organic molecules formed.
• May not have been done correctly.
• But experiments produced 20 amino acids, sugars, lipids, and some nucleotides.

Chemical reactions occur if dilute monomer solutions drip onto hot rocks or sand.

• Clays have charged regions that bind amino acids and hold them close together.
• Some metals (iron in pyrite) act as catalysts.

• Flow of information: DNA > RNA > protein
• RNA may have come first.
• Short pieces of RNA can be made naturally.
• RNA is autocatalytic - replicating.
• RNA binds to amino acids and helps them join.
• DNA is more complex and may have developed later.

• Protobionts = pre-cells
• Can be made abiotically (lipids in water).
• Show growth, splitting, and engulfment.
• oShow membrane potentials and excitability.