Geological Time Record

7/30/2019 Geological Time Record

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Dito tayo natapos last time. Pagdating dito sa Proterozoic, I ended up describing some pertinent species

of the type of biota that is prominent during the Proterozoic, represented by the Ediacaran fauna. Andaround that time nagsimula ang Precambrian which is Paleozoic wherein there is an assembling land

mass which is Rodinia (not yet Pangea). And as you can see, nagbrebreak pa siya, so we ended up here.

This was the super land mass being formed during the early time prior to the Cambrian. So, I want to go

on with this briefly, anyway, the general descriptions are given in the box.


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So at the start of Proterozoic, the Rodinia shown at the earlier slide was breaking apart at the beginning

of Paleozoic Era of which is the first period is the Cambrian. And one of the important characteristics of

Cambrian, as you can see, nagbreak apart ang Rodinia and these are the two major land masses for yourRodinia. So itong portion na ito, this will give rise to some major subcontinents or continents comprising

Asia, Europe and America. Ito naman, Africa plus Antartica, but red note is called Gondwana. These are

the two major break up regions of Rodinia during the start of your Paleozoic.

So it's Cambrian! During the Cambrian, with regards to its flora and fauna, well typically it is fauna which

undergone a great deal diversification on which in an adaptive radiation that we call the Cambrian

Explosion in which all the animal phyla are represented at that time, already, including Chordates. Nag-

exist na, during Cambrian. So those are the major points.

By the way, so most of the plate tectonics are moving the landmasses towards the equator. So you

would expect na ang temperature doon ay, as mentioned there, are ranging from tropical to subtropical

temperate. Not polar, because papuntang equator sila.


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Period Silurian. This is what I mean yan. Sa bandang taas dito, this is the Panthalasia. And dito, most of

the body of water found here is part of the Paleo-Tethys Ocean. Ito yung two large oceans formed

during the Paleozoic Era. So minor regions lamang ito, ____ and _____ these are the minor regions ofthe Paleo-tethys. So because prior to this, may Ice Age, so do you expect na may ice caps or ice sheets at

the start of this period. Ice sheets. Pero, at the middle of the Silurian Period, eventually, ang mga ice

sheets na yun, nagmelt and there is sort of warming in the climate occuring during the middle of the

Silurian. So, what kind of warming tended to isolate the glaciers at the high latitudinal areas, pwedeng

sa low latitudinal aread yung medyo warm ang mga landmasses mo of which there are many. Note,

merong mga landmasses pa rin, na at this point, meron. So those are where you would expect glaciers,

high latitudinal areas. But the low latitude areas were warm, and during this time, the major

appearances were sa mga dagat, coral reefs that are particularly abundant sa mga tropical regions and

ano pa. the first record of the vascular plants could have appeared here already sa Silurians. Much more

complex than your lichens and mosses. This is only a typical representation of the landscape would you

expect sa mga regions here in the equator. Relatively complex terrestrial systems could be found based

on the fossil record.


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Devonian. At this point, actually even before the Devonian nadidistinguish na ung two supercontinents,

the Gondwana and the Euamerica as mentioned kanina, un ang two major landmasses. Actually, as

shown by the arrows, they are being attracted to one another roughly around this time. There's also theEarth's surface covered by a vast ocean is still Panthalasia. Actually, yung inyong Paleo-tethys Ocean is

shrinking at this point. For the Paleozoic fauna, it is the height of the Paleozoic fauna. For the

vertebrates, dito dumarami ang mga fishes, kaya sinasabing ang Devonian Period is the Age of the

Fishes. So many many many many fishes at this point, as well as vascular plants and the arthropods are

the ones which comprise the terrestrial ecosystems. However, at the end of this period, me ron kang

second mass extinction. So it's the Devonian extinction and attributed to that, 70% of a lot of

invertebrates become extinct. Remember, this is massive geological plate tectonic movement and that

could have influenced the disappearance of many invertebrate sa dagat during this time at the end of

this period.

I think you have the copy of the file which mentions the five extinction events. And they are ordered from

the most recent to the oldest extinction event.


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Carboniferous. Sa mga American geologists, they tend to divide the Carboniferous into two parts. So the

early part is the Mississipian and the later part is the Pennsylvanian, so named after the kind of geologic

materials they found in those particular areas. Corresponding sila. In any case, uniform warming.Nagkaroon ka ng warming at the end of glaciation during the Devonian up to the beginning of

Carboniferous. And the characteristic of the terrestrial ecosystem is something like this. Mga swampy,

marshy body ecosystems, which are warm. And these kinds of ecosystems are conducive to the

deposition of peat material which today is our global coal reserves. So ang mga coal na nakukuha natin

in coal mines, actually came from the peat forests of the Carboniferous. Sila ang mga remains ng mga

yun. Relatively warm pa ang general climate, so ang mga ecosystems resembled tropical forests.

There's the Panthalassic Ocean, over here, and ito, bordered by some of the landmasses that's the

Paleo-tethys Ocean. Later on, in some references, sabi daw kasi, yung northern part of this ocean is

Paleo-tethys Sea and the southern part is simply Tethys Sea. And eventually, ang matitira lamang is the

south portion. Mawawala na ito, kasi your continents will be moving towards one another. Dito hindi pa

sila fully nabuo.


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But here, ano na ang evident during the Permian period? Evident na ang Pangea. Remember, your

Gondwana and Euramerica, di ba they are approaching one another, and ito na po ang inyong Pangea.

So more or less, along the Permian, sya ay nabuo. With regard to the dominant fauna, in this case,tuladnito, mostly gymnosperms, conifers. Also, nakikita ninyo? Actually, in the previous period, the basal land

tetrapods have already evolved. These particular animals would be herbivores. So they would be the

dominant invertebrates inhabiting the land during this period. And diversification of insects, including

winged insects.

And Permian extinction, largest extinction and the end of the Paleozoic fauna. So, any Paleozoic fauna

that were still existing would have become extinct at the end of the Permian during this time. Do

remember, kasi kapag naform itong Pangea, later on, magbrebreak apart naman ito. So often, a lot of

extinction events are related to geological activity, including volcanism and earthquakes possibly.


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Mesozoic na po tayo. In the table was Mesozoic, the Age of Reptiles. You have the Jurassic, Triassic and

the Cretaceous. The first of these is the Triassic.

So ito po ung ibig kong sabihin. So the northern part is the Paleo-tethys, the southern part is the Tethys.

Nandyan pa rin ang Pangea, although ang Gondwana, part pa rin sya, magbrebreak apart din yan. Polar

ice caps were absent, so the general climatic conditions would be relatively warm, conducive to the rise

of forest ecosystems in which the dinosaurs became predominant. At this time, nagsisimula ng maging

dominant ang mga large dinosaurs. Of course the peak of dominance in terms of diversity would be on

the Jurassic. Note that there are no polar ice caps, so it was the relatively warm climate that was present

during this time. First dinosaurs appeared, wala pang birds. How about plants? The dominant are still

the gymnosperms.

By the end of the Triassic, we know na nabuo na ito in the previous period , by the end of the Triassic,

magbrebreak apart din yan. The different geologic events seemed to be marked by coming together and

breaking apart. Di ba? Occurrence of glaciation, occurrence of warming, for example.


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Next is the Jurassic. Around the Jurassic, nagbreak apart na ang Pangea into two major masses which are

Laurasia and Gondwana (and the Panthalasia). Because of the breaking apart of Laurasia, medyo na may

mga nagdidivert o nagswisweep away na mga landmasses coming from Laurasia such that the total landarea of the Panthalasic Ocean would be reduced and Pacific Ocean is born. Or roughly around this time,

meron ka ng Pacific Ocean during Jurassic. Here's your Tethys Ocean, mostly Tethys na yan, so most of

the models galing na yan sa ___, so Tethys Ocean na yan, hindi na sya Paleo-tethys.

And this would be the typical environment of your Jurassic. Again, predominant pa rin ang mga conifers.

Gymnosperms. Of course the large dinosaurs are present. Giant sauropods, which are essentially the

dinosaurs.

Any glaciation? Wala. So you don't expect na may polar ice caps.

Special mention. I mentioned about cephalopods dito. Remember the ammonites? These are the

example of? Ammonites started to exist during this time. Zone fossils or index fossils. Ammonites

started to exist during this period, as well as f lying vertebrates. Remember which is the major landmass

event going on here? The separation of your Pangea into Laurasia and Gondwana. Pacific Ocean is

established nearly during the end of the Triassic period. Around the end of the Jurassic, itong portion na

ito, lalong lalo na itong dalawang ito, Central Atlantic Ocean. This will widen, and you will have your

Atlantic Ocean. So itong landmasses dito, hihiwalay pa, magiging body of water, that will be formed as

the Atlantic. Kaya kapag naghiwalay ito, the Atlantic will become a major barrier to the dispersal of

species between these two landmasses.


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Cretaceous. Cretaceous is so named because the characteristics of the sediments are expanse.Maraming maraming chalk na fossils. Kaya it's called Cretaceous. Creta, ang base word nyan is chalk.

Why? Kasi ang Pangea nagbrebreak up, syempre dumami ang mga coastlines mo. Dumami ang mga

daanan ng tubig dagat as your major landmass ____ during breaking apart. One very important biotic

occurrence during this time, the first flowering plants started to appear. Angiosperms. Pero wala pa ring

ice, wala pa ring major glaciation na nangyayari dito. So this ended roughly 65MYA with another mass

extinction event. So at the end of Triassic period up to the beginning of Cretaceous is the fourth mass

extinction event. The fourth mass extinction event coincided with the breaking apart of Pangea. The

fifth would be at the end of Cretaceous; and it is attributed to bolide impacts. Remember the Chicxulub

Crater? Saan? One of the major bolide impacts on the Earth happended around this time sa Yucatan

Peninsula, Mexico. And the kind of the rock that you find is the KT. for Cretaceous, T for Triassic. T

happens to be the next period. But now it is called PT, where P is for Paleogene, for the next period. Kasi

after Cretaceous, the next era is the Cenozoic Era. Kasi kung mapapansin nyo dito sa mapa, nasaan ang

Pilipinas? Wala pa. Ang Pilipinas po ay lilitaw sa Cenozoic. The bolide impact is not just only one;

actually, it is several. The fifth mass extinction is not attributed to a single bolide impact. There are

several. Another is the Sheva crater. Kasi malapit sya sa India. So it is not just one, but more than one.

Breaking of Pangea releases tremendous release of CO2, so if there is tremendous release of CO2 prior

to the end of bolide impacts, least likely na magkakaroon ng ice sheets, because the amount of CO2 will

tend to contribute to global warming.


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Cenozoic. Is the Age of the Mammals because the mammalian class started to undergo rapid

diversification and evolution. So we have here three epochs described. Paleocene, Eocene, up to the

Miocene and Triocene. Yung susunod kasi na era is Quarternary.


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Cenozoic. Is the Age of the Mammals because the mammalian class started to undergo rapid

diversification and evolution. So we have here three epochs described. Paleocene, Eocene, up to the

Miocene and Triocene. Yung susunod kasi na era is Quarternary.

So what's going on? This is 50MYA, during the Paleocene. This one is Eocene. Both the Paleocene and

Eocene, combined sila, is Paleogene Period. So this is Early, this is Middle Paleogene. Kaya naalala nyo

ung K-PG boundary? That's Cretaceous-Paleogene. Paleogene meaning the period covered by these two

epochs. Epochs po ito. Period would be the bigger, larger scale.

In Paleocene. Paleocene is characterized by a lot of mountain building in the process called orogeny.

And specifically, what kind of mountains were being built here? Yung nasa taas o, ung Alps in Europe.

Massive orogeny going on, which is continuing even up to Late Eocene. Himalayan pala, being built

during the days. Meron pa ring plate tectonics, pushing against another landmass, kaya upward.

Tumataas, kaya nagkakaroon ng mountain building.

In the Paleocene, sabi naman natin, wala pang masyandong glaciation na nag-ooccur, so you don't

expect na may polar ice caps around this epoch. There is a lot of orogeny going on. Also, land bridges are

prominent. What's land bridge? It is a landmass connecting continents. Continents are being connected

by a land bridge. How about South America and Antarctica? They don't have a land bridge because they

are connected to one another around the Paleocene.


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While at the end of this period, released methane from seafloor sediments. You have the release of this

methane conceived to our sediments implying that there is a lot of seafloor spreading going on. Kaya a

lot of seafloor sediments are in release kaya may global warming at the end of this period.

Hence the beginning of your Eocene. Because may mga methane gases proliferating at the start of

Eocene Epoch. And again, however, what is attributed to this warming? Methane released. Somewhat

similar to our carbon footprint ngayon na lumalaki.

If you want to read on the predominant fauna, anyway, they are described here. For example, the first

cetaceans appeare.. The first ungulates appeared. These are of course, they present the diversification

of mammals.

Oligocene. Mas more developed na yung Alps Himalayan mountain range in the Oligocene, which is the

result of your orogeny in the previous epochs. And what happened to your Tethys at this time?

Nagshrink na sya. And what is Tethys today? It is your Mediterranean Sea. So the Mediterranean Sea is a

remnant of your Tethys Ocean. And more of the body of water around here is the Indian Ocean. Indian

Ocean, kasi ang Indian Plate gumagalaw na doon. The sea plate in that ocean is mostly Indian Plate.

Meron din kasing bolide impact event that happened in Oligocene, and it was this one. Popigai Crater in

Siberia. Its not recent; it's Oligocene. Kaya in Siberia daw, dahil may bolide impact event dyan, is a

diamond mine.

This is Paleo, and this is Eo.. Look at the temperature. Nagdrop yung temperature. This is implying that

during Oligocene and the remaining epochs until today, relatively malamig ang temperature globally


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compared to all the epochs and periods preceding. So around this time, nagkakaroon na ng regular

glaciation events. Most particularly starting this period,Eocene Oligocene Period. So nagkakaroon ng

series of glaciation events which are said to be occuring until now. It was said that our current period is

an interglacial period. Which means that in the future, there will be another glaciation event. Because it

seems na that from this point onwards, they occur regularly in every 10-25,000 years.

Miocene and Pliocene. Still part of the previous period prior to the Quarternary. Ang Quarternary is the

period we are in right now. These are the epochs: Pleistocene and Holocene. Just refer to the geological

time record. I do not have the descriptions in the slides.


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Miocene. You have the Atlantic Ocean getting wider until achieving its size that it has now today during

the Miocene. There is what you call Great Faunal Interchange. Between Asia and North America, may

land bridge. And upon that land bridge, meron silang interchange. Ibig sabihin, some animals from Asiamigrated to North America, and some animals from North America migrated to Asia that occurred

around this period. And the bridge is called the Bering land bridge, which does not exist ngayon which is

____ by Atlantic Ocean.

Pliocene. The first hominids existed during the Pliocene. And there's another major land bridge. Panama.

Kung ang Bering land bridge is between Asia and North America, ang Panama land bridge is between

North and South America. So may faunal interchange between North and South America. The earliest

hominids existed during the Pliocene. Human-like. So meron pang Neanderthals dito and ancient Homo

sapiens. So ito pala yun, the Bering land bridge between Asia and North America.


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This is Early Miocene. 20MYA. So somewhere here. The Bering land bridge. This is representative of the

Quarternary period that we have now, in the present time. They are Pleistocene and Holocene. Some

other references refer to this as recent sa geological time record. More or less, during the Pleistocenethat's where you have major regularized occurrence of glaciation events and Homo sapiens became the

predominant Homo species, dahil they killed of the Neanderthals. At most during the Pleistocene, at the

height of glaciation, 30% is covered with ice. Dahil in the Pleistocene, dahil meron ka ng Homo sapiens,

meron ka ng tinatawag na megafaunal extinction. Ano itong megafaunal extinction na ito? Yung mga

animals that are representatives of the Ice Age like the mammoth, saber-toothed tiger, yung mga

malalaking animals, they were the animals na megafauna that were supposedly hunted to extinction by

humans kasi masyadong madaling mag____ ang humans. And then of course ..

Holocene. That is the recent. It is in the Holocene that we have the last glaciation event which is roughly

15,000-20,000 years ago. So right now, we have interglacial periods, and it estimated that another 10 -

15,000 before, we have prediction, another glaciation event. Kaya meron tayong global warming now,

kasi regular yung mga sparses ng glaciation event. Also, during the Holocene, civilizations started. Yan

yung mga Stone Age, Bronze Age, Iron Age, etc. Cultures of humans.

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