Transcript History of Life on Earth

Happy Thursday (10/16)
Write your thoughts on these pictures.
How do they relate to evolution?
History of Life on Earth
• SB5.b- Students will evaluate
the role of natural selection in the
development of the theory of
evolution.
• b. Explain the history of life in terms of
biodiversity, ancestry, and the rates of
evolution.
• c. Explain how fossil and biochemical
evidence support the theory.
•
https://www.youtube.com/watch?v=dY
phAH2tKYE
–
David A. 10 min Video/Intro
History of Life on Earth
• Began approximately 4.6 billion years ago
• Current speculations on formation of Earth
– Cosmic debris collected and cooled
– Planet experienced constant volcanic and
geological upheaval
– Anaerobic (no oxygen)
– Finally began to cool and form liquid water
Origin of Life: Prokaryotes
• Most popular theory
– Life first appeared a few million years after formation of Earth
– First organisms prokaryotic
– Select prokaryotes began to create oxygen
• This created aerobic atmosphere
Origin of Life: Eukaryotes
Eukaryotic cells appeared approximately 1.8 billion years ago
•
Endo- symbiotic theory
• Ancestors of eukaryotic cells
lived in close proximity to
bacteria and algae cells
• The ancestral eukaryotes
formed a symbiotic
relationship and became
incorporated into the bacteria
and algae cells
Origin of Life: Eukaryotes cont.
• Eukaryotic organisms
continued to evolve
•
• Sexual reproduction
began
– Increased genetic
variation
– New organisms
developed
– Gave rise to multicellular life
Geological Time Scale
• Represents
the evolution
of biodiversity
• 4 eras:
Precambrian,
Paleozoic,
Mesozoic,
and Cenozoic
• Each era is
broken into
periods
Precambrian
•
•
•
•
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Earth formed and first life appeared
Emergence of autotrophic prokaryotes (cyanobacteria)
Appearance of simple eukaryotes
Sexual reproduction begins
Multi-cellular organisms appear
– Sponges, cnidarians, and annelids
• Note: All life is aquatic!!
Paleozoic Era
543 Million Years Ago
• Cambrian explosion
– relatively rapid
appearance, of most
major animal phyla
– Approximately 490-443 MYA,
life on land appeared
– Mass extinction occurred at
end of this era (252 MYA)
• Wiped out 90-95% of
aquatic life, 60-70%
terrestrial life
Mesozoic Era
248 Million Years Ago
• Mammals, dinosaurs, birds and
flowering plants appear
• Dinosaurs dominated
• End of era meteorite hit near
the north coast of the presentday Yucatan
– 75% of life goes extinct
– Nothing above 25kg (55lbs)
survive
Pangea
• Pangea was a supercontinent
• Plate tectonics helped to
change the environment.
• Caused drastic geological
changes throughout the
Mesozoic era into the Cenozoic
era
• Plates began to drift apart
• Allowed for new species and
environments to form
Cenozoic Era
65 Million Years Ago to Present Day
• After the mass extinction,
mammals began to diversify
into distinct groups
• 500,000 years ago Homo
sapiens and Neanderthals
lived
• 65,000 years ago
Neanderthals die out
Quick Recap
• https://www.youtube.com/watch?v=ZSt9tm
3RoUU
– Life in 1 minute
• https://www.youtube.com/watch?v=7PQU
Rsc2SYs
– Mr Parr Eras song
Fossils
• Study of fossils is called paleontology
• Fossils are the remains of once living
organisms found in the rock layers of earth
– Found in sedimentary rock
• Fossils are used to establish relationships
among extinct and existing organisms
Fossil Record
• Show evidence of
evolution by providing
“snap shots” of ancient
organisms
• Used to create
evolutionary charts to
show how modern day
organisms evolved
• Ancestry is the history
of an organisms
development
How Old Are Fossils?
Grand Canyon
Now for a song…
• https://www.youtube.com/watch?v=RNSrN
T-nIDE
– Mr Parr
• https://www.youtube.com/watch?v=ClJ5lwl
_wM0
– Fossils Rock Anthem