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BIO 3102 Study Guide - Mind Map, Anoxic Event, Clathrate Hydrate


Department
Biology
Course Code
BIO 3102
Professor
All

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Mind Map Phanerozoic
Extinctions:
Background extinction happen all the time one species is replaced by another or is
unable to adapt after surviving a mass extinction. Mass extinction must be more than
50%.
Causes for mass extinction in general:
Astroids impact – An asteroid hits the earth sending up huge amount of debris and
space dust
causing a change in temperature which caused extinction. Original
hypothesis
doesn’t work for all extinctions because the craters from these
impacts don’t
match up with the time periods of all the extinctions.
Elevated carbon – Global warming (associated with all 5)
-From volcanos increasing carbon dioxide in the atmosphere causing global
warming
-From flood basalts which a tears in the earth crust releasing large amount of
magma and carbon dioxide. This happens on hot spots where the mantle is thin
and usually occurs with continents shifting. This is much more likely as much
more CO2 is released.
-Gas hydrates – Methane producing bacteria that live in the bottom of the oceans.
As they create methane because of the pressure of the water at that altitude is
solidifies into liquid form could be used as a source of energy if brought up to the
surface in a containment unit. If water levels drop then the pressure on the
methane reduced turn into methane gas and released into atmosphere. Could
allow for huge amount of methane to get into the air which is much more potent
gas than carbon dioxide
Marine anoxia – A reduction in the amount of oxygen in the oceans. No oxygen no life
and
extinctions ensue.
Sea level changes – melting of polar ice caps mean more water in the oceans could
lead to
marine anoxia. Reduction of water results in gas hydrates
expelling huge
amount of methane.
Major extinctions (who died, who survived and why)
End Cryogenian (no fully considered an extinction could be reason for multicellular
coming when it did) – Snow ball/ slush ball earth ( 3 possibilities)
1. The land masses reflected the light of the sun without warming the plant.

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2. The continents erosion removed large amount of CO2 from the atmosphere in the
form of carbon salts which would cool the earth.
3. The primary productivity in the oceans was so high that it took up most of the
CO2 which would cause the plants to cool.
It poles froze over and extended across the planet getting to such a size that it was
maintained as the light reflected off the glaciers preventing the earth from warming up.
Earth did melt finally probably due to volcanic activity on a global scale putting large
amount of CO2 back into the atmosphere to levels over 300 fold higher than what we
see today causing the earth to warm up. The thawing of the earth furnishes the bottom
of the oceans with sediments high in mineral nutrients his along with the high amount of
CO2 created a time of high productivity and diversity.
End Cambrian
End Ordovician
Late Devoninan – Due to flush if nutrients from dead plants less oxygen in oceans less
co2 in atmosphere
End Permian – 90% lost in oceans froze diversity change on land.
End Triassic – favors reptile first to get their egg on land is favored
End Cretacious – asteroid crashed temperature dropped productivity and biodiversity
dinosaurs died. Out of control population that out used the bottom levels of their trophic
pyramid caused collapse marine anoxia dropped temperature
Thing that are resistant to mass extinction are generalist small and globally distributed.
Time line:
Paleozoic
Multicellular life before Cambrian evidence
1. The chemical processes required for fossilization only appear at this point in time
we wouldn’t see any animals prior to this. Could still have been some.
2. The use of molecular clock to look at rates of change in the homeotic genes tell
us that these homeotic genes first appeared millions of years before the
Cambrian!
3. The Edecarian fossils which appear immediately prior to the start of the
Cambrian the earliest experiments in multicellular life.
4. the Doushantuo fossils. These are really unusual because they are microfossils
that look like embryos of multicellular organisms.
Burgess Shale fossils In Yoho National Park. Here, the invertebrates of the
Cambrian were fossilized in layers of shale that formed in the ancient Cambrian seas.
Flattened between layers of fine sediment like leaves pressed in a book, the fossils in
the rocks were ultimately thrust to the peaks of the Canadian Rockies. Split the layers in
the shale and there are the impressions of this unusual community of invertebrate
animals that lived then, and who are in part the ancestors to many of the animals that
still exist on the planet today.

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Doushantuo fossils – Microfossils that look like embryos with it’s simple 2, 4, 8 cell
formation. Could be representative of multicellular life that did not fossilize because too
soft bodied. Resets the age of multicellular life to beginning Ediacaran
Ediacaran fossils Fossils that prove multicellular life was around before the
Cambrian. Merited the creation of a new period at the end of Phanerozoic first addition
in over 100 years. Fossils found in Mistaken point Newfoundland dated to be
Precambrian. Unknown line of dissent horizontal burrowers originally thought to be soft
corals. Ediacaran fossils are some of earliest experiments in multicellular life.
Cambrian & Ordovician – water multicellular life
Cambrian  burges shales
Snowball
Huge productivity In oceans
Porifera (sponges)
Asymmetric (not tissue non communicating)
Covered in choanocytes (cells with a collar of microvilli around the flagella) which create
a water current by pumping water trapping any food in the microvilli collars.
Contain an outer pinacoderm, an inner choanoderm and in the middle
gelatinous mesohyl containing spicules (skeleton) and amoeboids which transfer
nutrients between cells after taking what they need.
There is a division of labour between cells but all cells are totipotent and can become
any type of cell
For reproduction sponges have sex they releases sperm that developed from
choanocytes and it goes into another sponge nearby and they fertilize eggs in the
sponge. The zygote then goes into a swimming stage where is leave the sponge and
settles somewhere else.
Cnidaria (Polyp/Jellyfish) – cnidocytes (sting)
Cell to cell communication real tissue therefor radially symmetric. Two forms in life
cycle simple sessile polyp colonies similar to sponges with stinging tentacles
(carnivore) with longitudinal and circular musculature (reproduce asexually). Moving
form medusa better known as jellyfish responsible for sexual reproduction.
Diploblast has both an endoderm and ectoderm along with mesonglea in the middle jelly
like elastic middle allows for motion (hydrostatic skeleton).
Water enters through a big hole the circular muscles contracts releasing water through a
small whole propelling the animal forward. The mesoglea allow the bell to open up
again without longitudinal muscles.
Incomplete gut formed through invagination creating a gastrula and a blastopore which
could become a protostome of deuterstome depending on what it becomes.
Start of bilateral symmetry (proto/deuter digestive tract)Triploblastic
Body cavity
Full coelom  space with muscles around gut and body ball with mesenteries in
between.
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