Download Chapter 14 The History of Life

Chapter 19
The History of Life
Chapter 19: History of Life
Early History of Earth
-The Earth is 4.1- 4.2 billion years old
-Life originated in Earth’s oceans
between 3.4 - 3.9 billion years ago
History in Rocks
Fossils:
Clues to the
past;
A fossil is
evidence of an
organism that
lived long ago
History in Rocks
Fossil formation:
- For fossils to form, organisms usually have to be
buried in mud, sand, or clay soon after they die.
- These particles are compressed over time and
harden into a type of rock called sedimentary rock.
History in Rocks
Trace fossil:
Foot prints,
nests/dens, or
fossilized feces
(poop)
Tell scientists about
the activities going
on at that time
History in Rocks
Mold:
Organism dies in soft
mold and leaves an
imprint of it’s body
History in Rocks
Cast:
Starts as a mold, but
over time a mixture of
water and minerals fill
in the mold
Makes a 3D model of
the organism
History in Rocks
Petrified/
Permineralized
fossil:
Minerals invade and
replace organism’s
parts as it dies
Makes very detailed
skeletons
Body is turned to
stone
History in Rocks
Amber-preserved
fossil:
-Organism lands on
a tree and gets stuck
in the tree sap
-Over time the sap
changes to Amber
stone
-Organism is often
perfectly preserved
History in Rocks
Relative dating:
-As layers of sediment
rock build on top of
each other, the fossils
in the deepest layers of
rock most be older than
those above them.
General age of fossil,
cannot be exact
-
History in Rocks
Radiometric dating:
Using radioactive
isotopes to age
fossils
Carbon-14
Potassium-40
Chlorine-36
-
A Trip Through Geologic Time
The geologic time scale
- The Precambrian
- The Paleozoic Era
- The Mesozoic Era
- The Cenozoic Era
Each era is subdivided into periods
Geological Calendar:
All of Time in just 1 year!
Formation of the Earth is
00:00 on 1/1
Geological Time Line Homework:
Create your own representation of the Geological Time
- Work in Groups of 3
- Must show the ratio used
- Must show all events listed on p. 454 and add
some your own
- Creative designs can get bonus points
- You will present your time line next class
- SHARE the work!
A Trip Through Geologic Time
The Precambrian Era
4570 – 542 million year ago
1)Life Begins
2)Prokaryotes form
3)Eukaryotes form
4)Invertebrates appear
-complex organisms
with no backbones
Geological Calendar:
2/25- 11/18
A Trip Through Geologic Time
Life during the Precambrian
Unicellular prokaryote appear
(4000- 3400 million years ago)
A Trip Through Geologic Time
Life during the Precambrian
More complex eukaryotic organism
appeared (2500 – 2100 million years ago)
A Trip Through Geologic Time
Life during the Precambrian
Multicellular eukaryotes, such as
sponges and jellyfishes, and
invertebrates diversified and
filled the oceans (543 million
years ago)
A Trip Through Geologic Time
The Paleozoic Era:
542-251 million years ago
-First Vertebrates
-First Fish
-First Land Plants
-First Amphibians
-First Reptiles
-First Trees
Geological Calendar:
11/18- 12/12
A Trip Through Geologic Time
Cambrian explosion
(535 to 525 million
years ago)
Dramatic increase in
number of species
Permian extinction
“The Great Dying”
-End of the Paleozoic Era
96% of Marine species
70% of vertebrates
83% of Insect species
-Caused by climate
change
-Hotter temperatures
-volcano activity
-Ice Age
-Dust reflects
sunlight
A Trip Through Geologic Time
The Mesozoic Era:
200-65 million years ago
-First dinosaurs
-First mammals
-First flowers
-First birds
Geological Calendar:
12/12 – 12/26
Mesozoic Mass Extinction:
Second largest extinction
Caused by an asteroid impact and
increased volcanic activity
Known as the K-T Extinction
Changing Earth’s Surface
Continental Drift
Movement of tectonic
plates
A Trip Through Geologic Time
The Cenozoic Era:
65 million years ago
– Present day
-Domination of
mammals
-Evolution of
Humans
-Modern Society
Geological Calendar:
12/26 – 12/31
P 390
Types of Evolution
Gradualism:
species originate through a
gradual change; small
changes over a long time
Punctuated equilibrium:
speciation occurs relatively
quickly, in rapid bursts, with
long periods of genetic
equilibrium
Patterns of Evolution
Divergent evolution:
species that once were similar to
an ancestral species diverge, or
become increasingly distinct.
Adaptive Radiation:
Ancestral species evolves into
many species to fit a number of
diverse habitats
Convergent evolution:
distantly related organisms evolve
similar traits
Origins: The Early Ideas
Spontaneous generation
The idea that nonliving material can
produce life
Origins: The Early Ideas
Spontaneous generation is
disproved by Francesco Redi:
• Maggots only grow
on meat exposed to
flies
• What about
microbes?
• There are bacteria
everywhere?! How
they must appear
from a life force in
the air…
Origins: The Early Ideas
Louis Pasteur:
• French Scientist
• One of the creators of Microbiology
and did experiments that supported
Germ Theory
1) Germs cause disease
2) Germs do not spontaneous
generate
• Biogenesis
•
The idea that living organisms
come only from other living
organisms
Origins: The Modern Ideas
Simple organic molecules formed
In the 1930s, a Russian scientist, Alexander
Oparin, hypothesized that life began in the
oceans that formed on early Earth.
Origins: The Modern Ideas
Simple organic molecules formed
In 1953, two American scientists, Stanley Miller
and Harold Urey, tested Oparin’s hypothesis by
simulating the conditions of early Earth in the
laboratory.
Origins: The Modern Ideas
The formation of protocells
A protocell(原细胞) is a large, ordered
structure, enclosed by a membrane, that
carries out some life activities, such as growth
and division.
Early Life Forms
Archaebacteria:
• First forms of complex
life; Can only survive in
extreme environments
• Used abundant organic
molecules for food
• Evolved to produce
glucose through
chemo-synthesis
Origins: The Modern Ideas
Photosynthesizing prokaryotes
Origins: The Modern Ideas
Death By Oxygen!
• Most species up to this
point were anaerobic
prokaryotes
• Creation of an oxygen rich
atmosphere changed
environment
• Dramatic shift in microbe
evolution
Origins: The Modern Ideas
The Endosymbiont Theory:
Eukaryotes evolved through a symbiotic
relationship between ancient prokaryotes.
Origins: The Modern Ideas
Experimental evidence shows:
-
Chloroplasts/Mitochondria
contain DNA that is similar
to the DNA in prokaryotes
Chloroplasts/Mitochondria
have their own ribosomes
Chloroplasts/Mitochondria
reproduce independently
That’s all