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History of Life 1
Brian O’MearaEEB464 Fall 2015
Tucson Botanical Gardens
Learning outcomes:
• Get a deep perspective on time• Understand major events in earth history• Generate hypotheses regarding what
happens after mass extinctions
Big Bang 13.73 BYA
First stars produce more complex elements, then
(some) explode
Borb
Solar system (sun, planets) form 4.6 BYA
Moon broken off from Earth, 4.53 BYA
Ow!
Heavy bombardment, 4.1 - 3.8 BYA
Life evolves~3.8 BYA
Photosynthesis evolvessomewhere 3.5 - 2.8 BYA
OH H
OCO
+ = OOSugar+
Great oxidation event2.45 - 2.22 BYA
OH H
OCO
+ = OOSugar+
Huronian glaciation3.2 - 2.4 BYA
a long time passesArchaea+Eukaryotes and Eubacteria
divergeEukaryotes diverge from Archaea
Life is still single-celled
An
dre
e V
alle
y
Bacteria Archaea Eukarya
Circular chromosome Y Y N
Histones with DNA N Y Y
Flagella Spinning Spinning Waving
Unicellular Y Y Varies
Organelles ~N N Y
a long time passesArchaea+Eukaryotes and Eubacteria
divergeEukaryotes diverge from Archaea
Life is still single-celled
An
dre
e V
alle
y
Ediacaran fauna0.63 BYA = 630 MYA
Wikimedia commons
Cambrian542 MYA
John Sibbick
Wikimedia commons
Permian-Triassic extinction251 MYA
Permian-Triassic extinction251 MYA
Permian-Triassic extinction251 MYA
KT (Cretaceous-Tertiary) extinction65.5 MYA
Brian Franczak
Sun eventually becomes red giant, expands
Franck et al. Causes and timing of future biosphere extinctions. Biogeosciences (2006) vol. 3 (1) pp. 85-92Schröder and Smith. Distant future of the Sun and Earth revisited. Monthly Notices of the Royal Astronomical Society (2008) vol. 386 (1) pp. 155-163
Life
evo
lves
Mul
ticellu
larit
y
NOW
Life
goe
s ex
tinct
Discussion: how might a major extinction like the one at the end of the Permian affect life?
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