BIOL 1F90 Study Guide - Final Guide: Disruptive Selection, Animal, Uniformitarianism

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Lecture 1 – History of Life on Earth
Know the Geological Time Scale.
- Precambrian Eon 4600 mya – 543 mya (4.6 bya – 543 mya)
o3.5 bya – single-celled prokaryotes
o2.5 bya – single-celled eukaryotes
o1.5 bya – multi-celled eukaryotes
- Phanerozoic Eon – 543 mya – 0 mya
oPaleozoic > Mesozoic > Cenozoic
oPaleozoic Era – 543 mya – 250 mya (paleo = early ancient zoic = animal life)
Cambrian explosion 525 mya
First vertebrates 520 mya
Permian Extinction 250 mya where 95% of all marine species eliminated due to
glaciations and volcanic eruptions
Periods in order: Cambrian Ordovician Silurian Devonian Carboniferous Permian
= Camels Often Sit Down Carefully, Perhaps
oMesozoic Era – 250 mya – 65 mya
Dinosaurs appear 200 mya
Cretaceous mass extinction 65 mya where dinosaurs go extinct due to large
meteorite and volcanic eruptions Kretaceous/Tertiary boundary
Periods in order: Triassic Jurassic Cretaceous = Their Joints Creak
oCenozoic Era – 65 mya – 0 mya
Homo sapiens appeared 130 000 years ago
Periods in order: Tertiary Quaternary
Describe the major environmental changes that have occurred on Earth.
- 5 large mass extinctions
oCambrian Period
Cambrian explosion – abrupt increase in diversity of animal species
oOrdovician Period
Warm temperatures
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Primitive land plants and arthropods
Climate change led to extinction (ice age) forming glaciers
oSilurian Period
Glaciers melt
Terrestrial plant and animal life
Coral reefs appeared
Many new fish appeared
Spiders and centipedes
oDevonian Age of Fishes
Lead to evolution of plants, insects and other animals
Gondwana drifted northerly
2 prolonged times of species depletion
Demise of great coral reefs, jawless fishes and trilobites
Also killed the placoderms and most early ammonites
Cause may be related to cooling climate from CO2 depletion caused by
first forests
Up to 70 percent of invertebrate species died, animals and plants hardly
affected
oCarboniferous Period
Oxygen levels high ~35%
Plant and insect were large, lots of swamp, and cooler temp
First flying insects
Amphibians appear
Large amounts of coal were created around this time
Many plant and animal species became extinct
oPermian period
Pangaea
Reptiles dominant
Largest mass-extinction
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90-95% of marine life died
So much biodiversity was lost on earth
One of three suggested reasons
oTemperature especially in water increased
oAlteration of the carbon cycle
oLow levels of dissolved oxygen
oTriassic Period
Dinosaurs appear
About 70 percent of plant and animal species perished
Meteorite or volcanic eruptions blamed
Describe how fossils are formed and how we know how old they are.
- Sediments pile up and become rock, organisms buried quickly and hard parts are replaced by
minerals
- Radioisotope dating
oFossils can be dated using elemental isotopes in accompanying rock
oFossil record will underestimate the actual date the species came into existence
- Burgess Shales fossils were from 500 mya
Explain the various biases that affect our interpretation of the fossil record.
- Researcher bias
oPaleontologists may be interested in certain types of fossils
- Population size
oMay not be many or any fossils of a certain species if the population was small
- Time
oMore recent fossils are easier to find than ancient ones
- Size of animal
oLarger animal fossils are easier to find than smaller animal fossils
- Hard vs soft bodies
oHard bodies (animals with shells) fossilize better than soft body animals
Review the basic differences between prokaryotes and eukaryotes.
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Document Summary

Lecture 1 history of life on earth. Precambrian eon 4600 mya 543 mya (4. 6 bya 543 mya: 3. 5 bya single-celled prokaryotes, 2. 5 bya single-celled eukaryotes, 1. 5 bya multi-celled eukaryotes. Phanerozoic eon 543 mya 0 mya: paleozoic > mesozoic > cenozoic, paleozoic era 543 mya 250 mya (paleo = early ancient zoic = animal life) Permian extinction 250 mya where 95% of all marine species eliminated due to glaciations and volcanic eruptions. Periods in order: cambrian ordovician silurian devonian carboniferous permian. = camels often sit down carefully, perhaps: mesozoic era 250 mya 65 mya. Cretaceous mass extinction 65 mya where dinosaurs go extinct due to large meteorite and volcanic eruptions kretaceous/tertiary boundary. Periods in order: triassic jurassic cretaceous = their joints creak: cenozoic era 65 mya 0 mya. Homo sapiens appeared 130 000 years ago. Describe the major environmental changes that have occurred on earth. Cambrian explosion abrupt increase in diversity of animal species: ordovician period.

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