BIO 1130 Lecture Notes - Lecture 12: National Bureau Of Economic Research, Protist, Doushantuo Formation
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Why in a short period in a few hundred million do we have this huge diversity. This goes completely
contract to how evolutionary biologist thinks that biodiverisy come are so important. The most diverse
assembly of large of animals appeared at the beginning of multicellular life. EVerthing else is depleteing.
Conntraty to thought the multilcular animals apppeard at the beginning of life. This led to a lot of
discussion.Maybe we weren’t seeing everything in the correct light.
Snowball Earth – at the very end of the proteriozoic the culmination of(before phanerzoic) protist life
. The position of the continents a large block of land. There is no green and no animls. Because this is
bear rock this is on the kind of material that holds on to heat very well. They rock gets warm but it
absorbs it and most of the heat gets reflected. That means the planete starts to cool. The ear rock is a
PRoblem: it Most of the heat is being reflected back up onto the planet. It is eroding. The water run off
is loading huge amounts of calcium and silica, minerals of rocks. Once we get vegetation =no more
erosion. We have mineralization. CO2 Cycle – Carbon dioxie in the water and atmosphere is in
equilibrium. How much CO2 is in the water. It forms sediments. Wat is happening- giant pulse of
minerals that is going into the ocean pulling ht ebicarbonate cycle causing minerlizaation. CO2 out of
the air (that is our earth blanket). We lose the insulation also we lose methan blacket. The methane is
a green house gas is deplteing as well. WE are losing heat because the loss of the two major gasing
depleting.. there is an ice mass that is created. They al replfect back the light. The radianat heating is
depleting. The continenetal land mass reflects.
IT hit a cricitcal point and it kept the earth frozen.
It froze multicellular life. There is stil life beneath the oceans. There is debate about snowball earth. The
earth hit a critical point. The whole planete was completely covered in ice. What is would say – we had
multicellular life deveiliping.
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Sulshball earth –arternative hypothesis. around the areas at the equataor there was still life that
continued around the hot zones.Snow ball earth is a rest point as the int hebiodivisy of the planets. This
is i=an dimpocation in the diversification of hte planet. All of the diversity stops. There is geothermal
veniting and outclassing nad v0lvanos.They it startsto warm the earth back up .
Cambrian :The evolution of multicellular life was onhold this was the snowball effect\If we look at the
CRYOGENENIAN- they are 2 set fossibls predante the Cambrian =-
they are very small. They are 1/10 of a milliteri in the fossil.
Doushantuo fossils look like emybros, they are very small. They
are the embryos of complex fossils. There is a different type of cell
division. 600 millioni years ago, there must have been something
o long ago. This indicated the multicellular life occurred even
earlier. embryos of fossilized org. There is a weird cell
Ediacarna fossils is found in NFLD. They date back to 580 million
years. There is a flatted organisms. They say that there were
complex forms of life there that have a complex structure. Inside
are impressions. Is it something that sat on the substrate What we
end up with – something that wasgoing on before the cabran
FRACTO – onbranch has other brances. They all predate the
Cambrian. There is another suggestion2nd piece of evidence.There
are little brances.They predate the Cambrian
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