1. History of Life on Earth

2. Claims, Evidence, Reasoning…
Statement about a scientific phenomenon
Evidence:
Scientific data used to support the claim
Reasoning:
Ties together the claim and the evidence

3. Life on Earth Today Claim: ~10 million species inhabit Earth today
Evidence: exploration!

4. Life on Earth Before Today
Claim: ~5 Billion species are extinct! (99%)

5. Evidence: Fossils Fossils:
Preserved remains of an organism from the past
Radiometric dating determines the age of the rock

6. When, where, & how did life form?

7. Event 1: Universe (space & time)
Claim: The universe expands ~13.8 bya
Evidence:
Microwave Background Radiation
Hubble’s Law

8. Event 2: Solar System Claim: Sun forms ~4.6 bya Evidence:
Solar Nebulae condenses, flattens
Lighter elements pulled by gravity form the sun
Evidence:
Hubble Observations
Astrophysics Modeling

9. Hadean Eon
billion years ago

10. Event 3: Earth Claim: ~4.6 bya Earth forms Evidence:
Heavy elements collide
No Water, No Oxygen, No Life, No Fun
Evidence:
Zircon crystals
Modeling of accretion disks

11. Event 4: Water Claim: ~4.5 bya water appears on Earth Evidence:
Icy comets and asteroids bombard Earth
Evidence:
Isotope measurements

12. Archean Eon
billion years ago

13. Event 5: Prokaryotic Life
Claim: ~3.9 bya prokaryotic cells appear
Genetic Material, Reproduce, Produced Oxygen
Evidence:
Fossils: Stromatolites
Primordial Soup Hypothesis

14. Proterozoic Eon
billion years ago

15. Event 6: Eukaryotic Life
Claim: ~2.1 bya eukaryotic cells appear
Internal Organelles
Evidence:
Fossils
Endosymbiosis Theory
Chloroplast, Mitochondria

16. Event 7: Multicellular Life
Claim: ~1.5bya multicellular life appears
Evidence:
Fossils
Colonial Flagellates

17. Phanerozoic
.54-0 billion years ago

18. Event 8: Animals Claim: ~530mya animals appear Evidence:
Fossils from the Cambrian Explosion

19. Mass Extinction 1 ~450 mya: Ordovician Extinction
90% of all species died
Major glacial event

20. Event 9: Colonizing Land
~ mya: Land Plants, Fungi, Amphibians
Fossils, Biogeography, Homology

21. Mass Extinction 2 ~360mya: Hangenberg Event 50% of all genera died
Climate changed rapidly, sea-levels decreased

22. Event 10: Colonizing the Air
Claim: ~350mya winged insects achieve flight
Super continent Pangaea forms
Evidence:
Fossils, Biogeography, Homology

23. Mass Extinction 3 ~250mya: The Great Dying 96% of all species died
Asteroids & Volcanoes

24. Event 11: Vertebrate Flight
Claim: ~230mya Early Dinosaurs appear
Pterosaurs soar through the air!
Evidence:
Fossils, Biogeography, Homology

25. Mass Extinction 4 Claim: ~200mya Pangaea Erupts 34% genera extinct
Volcanoes? Climate change? Asteroid impact?

26. Event 12: Age of “Terrible” Lizards
Claim: ~200mya dinosaurs and small mammals appear
Evidence:
Fossils, Biogeography, Homology

27. Mass Extinction 5 Claim: ~65mya K/T Extinction 75% of all species died
Giant asteroid slammed into Mexico

28. Event 13: Mammal Diversification
Claim: ~60 mya small mammals diversify
Mammal radiation occurs
Evidence:
Fossils, Biogeography, Homology

29. Event 14: Humans ~200,000 years ago: Homo sapiens Evidence:
Fossils, Biogeography, Homology

30. Mass Extinction 6
Habitat Destruction, Hunting, Pollution, Climate change… all caused by HUMANS

31. Critically Endangered Species

32. Into the Future