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Phanerozoic Eon

phanerozoic.htm

from Wikipedia: - https://en.wikipedia.org/wiki/Phanerozoic 180513

Downloaded and edited by U Kyaw Tun (UKT) (M.S., I.P.S.T., USA), and staff of Tun Institute of Learning (TIL) . Not for sale. No copyright. Free for everyone. Prepared for students and staff of TIL Research Station, Yangon, MYANMAR 
 - http://www.tuninst.net , www.romabama.blogspot.com

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geol-indx.htm

Contents of this page

UKT 180515: This folder deals with Eon > Era > Period

Introduction:

1.0. Proterozoic-Phanerozoic Eon boundary

2.0. Eras of the Phanerozoic Eon

2.1. Paleozoic Era
2.1.1. Cambrian Period
2.1.2. Ordovician Period
2.1.3. Silurian Period
2.1.4. Devonian Period
2.1.5. Carboniferous Period
2.1.6. Permian Period

2.2. Mesozoic Era
2.2.1. Triassic Period
2.2.2. Jurassic Period
2.2.3. Cretaceous Period

2.3. Cenozoic Era
2.3.1. Paleogene Period
2.3.2. Neogene Period
2.3.3. Quaternary Period

The following are still linked to Wikipedia:

• 3 Biodiversity
• 4 See also
• 5 Notes
• 6 References
• 7 External links

UKT notes
• Craton : Shield
• Siberia Paleocontinent

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Introduction

The Phanerozoic Eon [3] is the current geologic eon in the geologic time scale, and the one during which abundant animal [fauna] and plant life [flora] has existed. [UKT ¶]

UKT 180513: The English word "animal" is commonly understood in Bur-Myan as "one who knows only how to eat, to sleep, and to mate - without knowing what is morally good or bad" which excludes "humans". For clarification to the Bur-Myan audience, I've added the word "fauna".

Now, add the word "life", and the confusion is complete. "Life" to us is defined by the Buddhist Five Precepts "abstinence of killing" which excludes the "plant life". Going further, I usually ask: "does the chicken-egg , sold in present-day market in Myanmarpré, living or not".

You can go on arguing if you are Burmese Buddhist layman, who, at least on paper, keeps the Five Precepts.

I rest my argument by asking whether the chicken-egg can be hatched or not. If it can be hatched it has Life. However, the matter is clarified for the Buddhist monks and nuns, who are forbidden to eat seeds of plants because they can give rise to new plants.

It covers 541 Ma to the present, [4] and began with the Cambrian Period when diverse hard-shelled animals first appeared. Its name was derived from the Ancient Greek words φανερός  phanerós and ζωή zōḗ , 'visible life'. It was once believed that life began in the Cambrian Period, the first period of this eon. The time before the Phanerozoic Eon, called the Precambrian supereon, is now divided into the Hadean, Archaean and Proterozoic eons.

UKT 180513: The original Wikipedia statement "time before the Phanerozoic" without the "Eon", is a misleading statement. Without the "Eon" - the suffix I've added, has mislead me before this present study. The misleading statement continues by adding the "Precambrian" . It has mixed up the time-scales. Wikipedia should have said "time before the Phanerozoic Eon, is "Proterozoic Eon, the last eon of the Precambrian Supereon".

 The time span of the Phanerozoic starts with what appears to be the rapid emergence of a number of animal phyla; the evolution of those phyla into diverse forms; the emergence and development of complex plants; the evolution of fish; the emergence of insects and tetrapods; and the development of modern fauna. [UKT ¶]

UKT 180514: In Biology - plants and animals - are classified into:
  Life > Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
See Wikipedia: https://en.wikipedia.org/wiki/Taxonomy_(biology) 180515
"Taxonomy (from Ancient Greek τάξις (taxis) 'arrangement', and -νομία (-nomia) 'method' is the science of defining and naming groups of biological organisms on the basis of shared characteristics."

For Vascular plants, refer to the first book on Botany, thanks to my family friend the late U Maung Maung Pyone, that I've studied: Taxonomy of Vascular Plants, by G H M Lawrence, 1951, in Sec. 9,
  Paramedicine > taxon-indx.htm (link chk 180514)

Plant life on land appeared in the early Phanerozoic eon.  [UKT ¶]

UKT: See how Plants are defined - https://en.wikipedia.org/wiki/Plant 180514
" Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae."

During this time span, tectonic forces caused the continents to move and eventually collect into a single landmass known as Pangaea (the most recent supercontinent), which then separated into the current continental landmasses.

See downloaded VIDEOs in TIL HD-VIDEO and SD-VIDEO libraries in folder GEOLOGY ¤ 3. Continental drift
- ContinetDrift<Ô> / Bkp<Ô> (link chk 180306)

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1.0. Proterozoic-Phanerozoic Eon boundary

The Proterozoic Eon - Phanerozoic Eon boundary is at 541 Ma ago. [5]. [UKT¶]

In the 19th century, the boundary was set at time of appearance of the first abundant animal (metazoan) fossils but several hundred groups (taxa) of metazoa of the earlier Proterozoic era have been identified since the systematic study of those forms started in the 1950s. Most geologists and paleontologists would probably set the Proterozoic-Phanerozoic boundary either at the classic point where the first trilobites and reef-building animals (archaeocyatha) such as corals and others appear; at the first appearance of a complex feeding burrow called Treptichnus pedum; or at the first appearance of a group of small, generally disarticulated, armored forms termed 'the small shelly fauna'. The three different dividing points are within a few million years of each other.

In the older literature, the term Phanerozoic is generally used as a label for the time period of interest to paleontologists, but that use of the term seems to be falling into disuse in more modern literature.

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2.0. Eras of the Phanerozoic Eon

The Phanerozoic Eon is divided into three eras and 12 periods
#1. Paleozoic Era :
  Cambrian Period, Ordovician Period, Silurian Period, Devonian Period, Carboniferous Period, Permian Period
#2. Mesozoic Era :
  Trassic Period, Jurassic Period, Cretaceous Period
#3. Cenozoic Era :
  Paleogene Period, Neogene Period, Quaternary Period
- a total of 12 periods [UKT ¶] 

The Paleozoic Era features the rise of fish, amphibians and reptiles.
The Mesozoic Era is ruled by the reptiles, and features the evolution of mammals, birds and more famously, dinosaurs.
The Cenozoic Era is the time of the mammals, and more recently, humans.

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2.1. Paleozoic Era : 541-250 Ma ago

The Paleozoic Era is a time in Earth's history when complex life forms evolved, took their first breath of oxygen on dry land, and when the forerunners of all life on Earth began to diversify. There are six periods in the Paleozoic era  [6]:
#1. Cambrian Period
#2. Ordovician Period
#3. Silurian Period
#4. Devonian Period
#5. Carboniferous Period 
#6. Permian Period

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2.1.1. Cambrian Period : 541-485 Ma ago

UKT 180515: Don't be mislead by the term Precambrian, which stands for a Supereon.

The Period before the Cambrian Period is Ediacaran Period spanning between 635-543 Ma ago.
See: https://courses.lumenlearning.com/boundless-biology/chapter/the-evolutionary-history-of-the-animal-kingdom/ 180515

See also Wikipedia: https://en.wikipedia.org/wiki/Ediacaran 180515
"The Ediacaran Period, spans 94 Ma from the end of the Cryogenian Period 635 Ma ago, to the beginning of the Cambrian Period 541 Ma ago. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia."

The Cambrian Period is the first period of the Paleozoic Era spans 541-485 Ma ago. [UKT ¶]

The Cambrian Period sparked a rapid expansion in evolution in an event known as the Cambrian Explosion during which the greatest number of creatures evolved in a single period in the history of Earth. [UKT ¶]

UKT 180513: Cambrian Explosion
- https://en.wikipedia.org/wiki/Cambrian_explosion 180513
The Wikipedia does not have anything relating to temperature which should be a factor that caused the rapid expansion in evolution. I do not accept everything that I read in Wikipedia or any other sources. I'm just an informed reader, opinionated maybe, but never dogmatic. The following is an article relating temperature change to the onset of Cambrian explosion.

Plants detonated Cambrian explosion : Global cooling may have allowed complex animals to flourish.
- John Whitfield, https://www.nature.com/news/2003/031001/full/news030929-4.html 180513
"The first land plants might have triggered a rush of animal evolution. German researchers are proposing a controversial theory that the plants cooled Earth, making it conducive to complex life [footnote 1].
   The idea is a new twist on the Gaia hypothesis that living things influence the global environment. "During the evolution of the Earth there was a decrease in temperature, and higher life forms have lower temperature limits," says Werner von Bloh of the Potsdam Institute for Climate Impact Research.
   Many researchers think that rising, not falling, temperatures lit the fuse for the Cambrian explosion, the biological Big Bang 540 million years ago when most modern animal groups appear in the fossil record.
  There is genetic evidence that simple plants, such as algae and lichens, colonized the land 800 Ma ago. But no plant fossils from this time have been found.
  It's also unclear whether there was a slump in temperatures, and whether such a drop would have favoured complex life. Says palaeontologist Robert Riding of Cardiff University, UK: "Nobody knows what's right or wrong, but it sounds odd to me".
  But the link between temperature and life deserves further investigation, argues geochemist David Schwartzman of Howard University in Washington DC. "The global emergence of certain types of organism could be tied to their optimum temperature," he says. ..."
footnote 1. von Bloh, W., Bounama, C. & Franck, S. Cambrian explosion triggered by geosphere-biosphere feedbacks. Geophysical Research Letters, 30, 1963, doi:10.1029/2003GL017928, (2003)

Plants like algae evolved, and the fauna was dominated by armored arthropods, such as trilobites. Almost all marine phyla evolved in this period. During this time, the super-continent Pannotia began to break up, most of which later recombined into the super-continent Gondwana. [7]

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2.1.2. Ordovician Period : 485-440 Ma ago

The Ordovician Period spans from 485 Ma to 440 Ma ago. [UKT ¶]

The Ordovician was a time in Earth's history in which many species still prevalent today evolved, such as primitive fish, cephalopods, and coral. [UKT ¶]

The most common forms of life, however, were trilobites, snails and shellfish. More importantly, the first arthropods crept ashore to colonize Gondwana, a continent empty of animal life. By the end of the Ordovician, Gondwana had moved from the equator to the South Pole, and Laurentia had collided with Baltica, closing the Iapetus Ocean. The glaciation of Gondwana resulted in a major drop in sea level, killing off all life that had established along its coast. Glaciation caused a snowball Earth, leading to the Ordovician-Silurian extinction, during which 60% of marine invertebrates and 25% of families became extinct. This is considered the first mass extinction and the second deadliest in the history of Earth. [8]

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2.1.3. Silurian Period : 440-415 Ma ago

The Silurian Period spans from 440 Ma to 415 Ma ago [UKT ¶]

The Silurian Period saw a warming from Snowball Earth. [UKT ¶]

This period also saw the mass evolution of fish, as jaw-less fish became more numerous, jawed fish evolved, and the first freshwater fish evolved, though arthropods, such as sea scorpions, remained the apex predators. [UKT ¶]

Fully terrestrial life (both animals and plants) evolved, which included early arachnids, fungi, and centipedes. The evolution of vascular plants ( Cooksonia) allowed plants to gain a foothold on land. These early terrestrial plants are the forerunners of all plant life on land. [UKT ¶]

UKT 180517: Aquatic animals - both marine and fresh water - need diatomic oxygen for their metabolism. They must have special apparatus such as gills to extract oxygen from water. However, for the terrestrial animals they must absorb atmospheric O₂ with lungs.

During this time, there were four continents:

UKT 180516: Wikipedia's use of "continents" is misleading. When I dated the "continents", I found them to be supercontinents or something else. Wikipedia does not tell us about how these four "continents" were formed, nor how they compare to supercontinent Pangaea?

#1. Gondwana supercontinent : 550-320 Ma ago
  (Africa, South America, Australia, Antarctica, India): See https://en.wikipedia.org/wiki/Gondwana 180516

#2. Laurentia continental craton :
  (North America with parts of Europe): See https://en.wikipedia.org/wiki/Laurentia 180516

"Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of the North American continent. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America".
See my note on craton .

#3. Baltica paleocontinent :
  (the rest of Europe): See https://en.wikipedia.org/wiki/Baltica 180516

"Baltica is a paleocontinent that formed in the Paleoproterozoic , and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, is more than 3 Ga old and formed part of the Rodinia supercontinent at c. 1 Ga ago. [1]

#4. Siberia paleocontinent
  (Northern Asia).  [UKT ¶] : See Siberia paleocontinent in my notes.

The recent rise in sea levels provided new habitats for many new species. [9]

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2.1.4. Devonian Period : 415-360 Ma ago

The Devonian Period spans from 415 Ma to 360 Ma ago. Also known as the "Age of the Fish", the Devonian features a huge diversification in fish, including armored fish like Dunkleosteus and lobe-finned fish which eventually evolved into the first tetrapods. [UKT ¶]

UKT 180519: Always associate the Devonian Period with two big events:
1. Devonian Explosion - https://creativeandevolution.wordpress.com/2013/05/27/plants-and-the-devonian-explosion/ 180519
   "Plants took off during the Devonian period to such an extent it was called the Devonian explosion.  As the Devonian period proceeded the plants were causing their own demise as the amount of carbon dioxide was decreasing.  The plants reacted to this by making more stomata and started to make webbing on the leaves to increase the surface area to take in even more carbon dioxide. ..."
2. Late Devonian extinction - https://en.wikipedia.org/wiki/Late_Devonian_extinction 180519
   "The Late Devonian extinction was one of five major extinction events in the history of the Earth's biota."

Note: The pix which Wikipedia gives with the paragraph is misleading. Eogyrinus (an amphibian) of the Carboniferous Period, which I've moved to its proper paragraph below. See: https://en.wikipedia.org/wiki/Eogyrinidae 180519
"Eogyrinidae is an extinct family of large, long-bodied tetrapods that lived in the rivers of the Late Carboniferous period."
See also: https://en.wikipedia.org/wiki/Eogyrinus 180519
"Eogyrinus attheyi (from Greek eos, meaning "dawn", and gyrinos, meaning "tadpole") was one of the largest Carboniferous tetrapods, and perhaps one of the largest of its family, Eogyrinidae, at 4.6 metres (15 ft) in length. [1]"
See also: https://en.wikipedia.org/wiki/Diplovertebron 180519
"Diplovertebron is an extinct genus of Anthracosauria (labyrinthodont) that lived in the Late Carboniferous period (Moscovian) (310 Ma  ago). Diplovertebron was a medium-sized animal, 60 cm in length.

On land, plant groups diversified incredibly in an event known as the Devonian Explosion during which the first trees evolved, as well as seeds. This event also allowed the diversification of arthropod life as they took advantage of the new habitat. The first amphibians also evolved, and the fish were now at the top of the food chain. [UKT ¶]

Near the end of the Devonian Period, 70% of all species became extinct in an event known as the Late Devonian extinction, which is the second mass extinction known to have happened. [10]

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2.1.5. Carboniferous Period : 360-300 Ma ago

  The Carboniferous spans from 360 Ma to 300 Ma ago. During this period, average global temperatures were exceedingly high: the early Carboniferous averaged at about 20 degrees Celsius (but cooled to 10 degrees during the Middle Carboniferous). [11] [UKT ¶]

UKT 180519: The two pix show giant amphibians. Eogyrinus is a giant tadpole, which changes into a giant four-legged amphibian.

Tropical swamps dominated the Earth, and the large amounts of trees created much of the carbon that became coal deposits (hence the name Carboniferous). The high oxygen levels caused by these swamps allowed massive arthropods, normally limited in size by their respiratory systems, to proliferate. Perhaps the most important evolutionary development of the time was the evolution of amniotic eggs, which allowed amphibians to move farther inland and remain the dominant vertebrates throughout the period. Also, the first reptiles and synapsids evolved in the swamps. Throughout the Carboniferous, there was a cooling pattern, which eventually led to the glaciation of Gondwana supercontinent (550-320 Ma ago) as much of it was situated around the South Pole, in an event known as the Permo-Carboniferous glaciation or the Carboniferous Rainforest Collapse. [12].

UKT 180517: Whenever you come across the word "Pole" make sure whether it is the geographic or magnetic.

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2.1.6. Permian Period : 300-250 Ma ago

The Permian Period spans from 300 Ma to 250 Ma ago and was the last period of the Paleozoic Era. At its beginning, all continents came together to form the super-continent Pangaea, surrounded by one ocean called Panthalassa. [UKT ¶]

UKT 180517: Note: My views may change from time to time as my knowledge increases.
My main interest is in the Geology of Myanmarpré. Why is my native-country so rich in natural resources ?

See a video in section on Geology in TIL HD-VIDEO and SD-VIDEO libraries
¤ Types of rocks : Science video for kids
- Types of Rocks<Ô> / Bkp<Ô> (link chk 180517)

Because of the visible coast-line of Burma in the map of the Pangaea super-continent I am interested in this particular supercontinent, which is surrounded by Panthalassa ocean and Thethys ocean. Heavy metals like gold, silver, copper, tungsten either as pure metal or compounds had settled to bottom of the ocean -- Paleo-Thethys. It is this ancient mineral wealth that we in Myanmarpré are enjoying today.

We are rich in natural gas, but coal deposits are scarce. Even the coal is the soft kind not valuable as a fuel. Availability of petroleum oil is moderate, but our oil is "sweet" unlike the Arabian oil which is "sour" with a high sulphur content.

Our oil is deficient in low boiling components - the gasoline fraction, but rich in kerosene fraction. Our wax is of best quality. My answer to these questions undoubted lies in the Pangaea supercontinent and the Thethys Ocean.

UKT 180518: For more information about Petroleum deposits, you should refer to Petroleum systems of the Tethyan region, by F. Berra and L. Angiolini, in AAPG Memoir -
- http://wiki.aapg.org/Phanerozoic_Tethys_region 180518
"The distribution of giant oil and gas fields in North Africa, Arabia, and the Middle East is the result of the interplay between the paleogeography of oceanic and continental areas, which favored the creation of source rocks, and the geodynamic evolution of Pangea and the Tethys Oceans during the Phanerozoic Eon. ... Early Permian (about 290 Ma): The late Paleozoic was a period of major plate tectonic reconfiguration (Figure 5) [UKT: I've left out Fig.5]. The Variscan orogeny led to the assembly of Gondwana and Laurasia into one supercontinent, ..."

 

The Earth was very dry during this time, with harsh seasons, as the climate of the interior of Pangaea wasn't regulated by large bodies of water. Reptiles and synapsids flourished in the new dry climate. Creatures such as Dimetrodon and Edaphosaurus ruled the new continent. The first conifers evolved, then dominated the terrestrial landscape. Nearing the end of the period, Scutosaurus and gorgonopsids filled the empty desert. Eventually, they disappeared, along with 95% of all life on Earth in an event simply known as "the Great Dying", the world's third mass extinction event and the largest in its history. [13] [14]

From: http://www.ucmp.berkeley.edu/permian/permian.php 180515

The Permian period lasted from 299-251 Ma ago* and was the last period of the Paleozoic Era. [UKT ¶]

The distinction between the Paleozoic Era and the Mesozoic

is made at the end of the Permian in recognition of the largest mass extinction recorded in the history of life on Earth. It affected many groups of organisms in many different environments, but it affected marine communities the most by far, causing the extinction of most of the marine invertebrates of the time. Some groups survived the Permian mass extinction in greatly diminished numbers, but they never again reached the ecological dominance they once had, clearing the way for another group of sea life. [UKT ¶]

On land, a relatively smaller extinction of diapsids and synapsids cleared the way for other forms to dominate, and led to what has been called the "Age of Dinosaurs." Also, the great forests of fern-like plants shifted to gymnosperms, plants with their offspring enclosed within seeds. Modern conifers, the most familiar gymnosperms of today, first appear in the fossil record of the Permian. The Permian was a time of great changes and life on Earth was never the same again. ...

The current stratigraphy divides the Permian into three series or epochs:
- the Cisuralian Epoch (299 to 270.6 Ma),
- Guadalupian Epoch (270.6 to 260.4 Mya)
- Lopingian Epoch (260.4 to 251 Ma).*
  * Dates from the International Commission on Stratigraphy's International Stratigraphic Chart, 2009.

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2.2. Mesozoic Era : 252-66 Ma ago

The Mesozoic ranges from 252-66 Ma ago. Also known as "the Age of the dinosaurs", the Mesozoic features the rise of reptiles on their 150 million year conquest of the Earth on the land, in the seas, and in the air. There are three periods in the Mesozoic:
#1. Triassic Period
#2. Jurassic Period
#3. Cretaceous Period.

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2.2.1. Triassic Period

The Triassic Period ranges from 250 Ma to 200 Ma ago. The Triassic Period is a desolate transitional time in Earth's history between the Permian Extinction and the lush Jurassic Period. It has three major epochs: [15]
#1. Early Triassic Epoch
#2. Middle Triassic Epoch
#3. Late Triassic Epoch.

The Early Triassic Epoch lasted between 250 Ma to 247 Ma ago, and was dominated by deserts as Pangaea had not yet broken up, thus the interior was arid. The Earth had just witnessed a massive die-off in which 95% of all life became extinct. The most common life on Earth were Lystrosaurus, labyrinthodonts, and Euparkeria along with many other creatures that managed to survive the Great Dying. Temnospondyli evolved during this time and would be the dominant predator for much of the Triassic Period. [16]

The Middle Triassic spans from 247 Ma to 237 Ma ago. The Middle Triassic Epoch featured the beginnings of the breakup of Pangaea, and the beginning of the Tethys Sea. The ecosystem had recovered from the devastation of the Great Dying. Phytoplankton, coral, and crustaceans all had recovered, and the reptiles began increasing in size. New aquatic reptiles, such as ichthyosaurs and nothosaurs, evolved. Meanwhile, on land, pine forests flourished, as well as mosquitoes and fruit flies. The first ancient crocodilians evolved, which sparked competition with the large amphibians that had long ruled the freshwater world. [17]

The Late Triassic Epoch spans from 237 Ma to 200 Ma ago. Following the bloom of the Middle Triassic Epoch, the Late Triassic featured frequent rises of temperature, as well as moderate precipitation (10-20 inches per year). The recent warming led to a boom of reptilian evolution on land as the first true dinosaurs evolved, as well as pterosaurs. The climactic change, however, resulted in a large die-out known as the Triassic-Jurassic extinction event, in which all archosaurs (excluding ancient crocodiles), synapsids, and almost all large amphibians became extinct, as well as 34% of marine life in the fourth mass extinction event. The extinction's cause is debated. [18] [19]

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2.2.2. Jurassic Period

The Jurassic Period ranges from 200-145 Ma ago, and features three major epochs [20]:
#1. Early Jurassic Epoch
#2. Middle Jurassic Epoch
#3. Late Jurassic Epoch

The Early Jurassic Epoch spans from 200-175 Ma ago. [20] [UKT ¶ ]

The climate was much more humid than the Triassic Period, and as a result, the world was very tropical. In the oceans, plesiosaurs, ichthyosaurs and ammonites dominated the seas. On land, dinosaurs and other reptiles dominated the land, with species such as Dilophosaurus at the apex. The first true crocodiles evolved, pushing the large amphibians to near extinction. The reptiles rose to rule the world. Meanwhile, the first true mammals evolved, but never exceeded the height of a shrew. [21]

The Middle Jurassic Epoch spans from 175-163 Ma ago. [20] [UKT ¶ ]

During this epoch, reptiles flourished as huge herds of sauropods, such as Brachiosaurus and Diplodicus, filled the fern prairies of the Middle Jurassic. Many other predators rose as well, such as Allosaurus. Conifer forests made up a large portion of the world's forests. In the oceans, plesiosaurs were quite common, and ichthyosaurs were flourishing. This epoch was the peak of the reptiles. [22]

The Late Jurassic Epoch spans from 163-145 Ma ago. [20] [UKT ¶ ]

The Late Jurassic featured a massive extinction of sauropods and ichthyosaurs due to the separation of Pangaea into Laurasia and Gondwana in an extinction known as the Jurassic-Cretaceous extinction. Sea levels rose, destroying fern prairies and creating shallows. Ichthyosaurs became extinct whereas sauropods, as a whole, did not; in fact, some species, like Titanosaurus, lived until the K-T extinction. [23] The increase in sea-levels opened up the Atlantic sea way which would continue to get larger over time. The divided world would give opportunity for the diversification of new dinosaurs.

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2.2.3. Cretaceous Period

The Cretaceous Period is the longest period in the Mesozoic, spans from 145-66 Ma ago, and is divided into two epochs [24]:
#1. Early Cretaceous Epoch
#2. Late Cretaceous Epoch 

The Early Cretaceous Epoch spans from 145-100 Ma ago. [24] [UKT ¶]

The Early Cretaceous saw the expansion of seaways, and as a result, the decline and extinction of sauropods (except in South America). Many coastal shallows were created, and that caused ichthyosaurs to die out. Mosasaurs evolved to replace them as apex species of the seas. Some island-hopping dinosaurs, like Eustreptospondylus, evolved to cope with the coastal shallows and small islands of ancient Europe. Other dinosaurs, such as Carcharodontosaurus and Spinosaurus, rose to fill the empty space that the Jurassic-Cretaceous extinction had created. Of the most successful would be the Iguanodon which spread to every continent. Seasons came back into effect and the poles grew seasonally colder. Dinosaurs such as the Leaellynasaura inhabited the polar forests year-round, while many dinosaurs, such as the Muttaburrasaurus, migrated there during summer . Since it was too cold for crocodiles, it was the last stronghold for large amphibians, such as the Koolasuchus. Pterosaurs grew larger as species like Tapejara and Ornithocheirus evolved. More importantly, the first true birds evolved sparking competition between them and the pterosaurs.

UKT 180520: Much of the Irrawaddy basin would have been under shallow sea water, and the sizable land would have been the Shan Plateau. Arakan Yoma would have been there and foothills of Himalayas further north-west and we would have our own share of giant lizards the 'dinosaurs', one being Siamosuarus - of Early Cretaceous Epoch - which might have reached a length of about 9.1 meters (30 ft). However there might have been large mammals - large enough to hunt smaller dinosaurs.

From: Large mammals once dined on dinosaurs, by J. Hecht, 2005Jan12, daily news - https://www.newscientist.com/article/dn6874-large-mammals-once-dined-on-dinosaurs/ 180520

"When the dinosaurs ruled the world, the mammals hid in the shadows, daring to grow no bigger than shrew-like insectivores that hunted at night. Or so we thought.

"Two stunning new fossils from China have overturned this preconception. Not only did large mammals live alongside their giant reptilian cousins, but some were big and bold enough to go dinosaur hunting.

"Named Repenomamus giganticus and Repenomamus robustus, the sturdily built mammals lived in China about 130 Ma ago, around 65 million years before we thought their kind inherited the Earth. At 1 metre long, R. giganticus was big enough to hunt small dinosaurs, and a newly discovered fossil of its smaller cousin, R. robustus, died with its belly full of young dinosaur.

"This totally overturns the notion of dinosaur-age mammals as tiny and nocturnal, says vertebrate palaeontologist Hans-Dieter Sues of the Smithsonian Institution in Washington DC, US. “Apparently some mammals could grow much larger than anyone had thought was possible.”

The Early Cretaceous Epoch spans from 145 million to 100 million years ago. [24] [UKT ¶ ]

The Early Cretaceous saw the expansion of seaways, and as a result, the decline and extinction of sauropods (except in South America). Many coastal shallows were created, and that caused ichthyosaurs to die out. Mosasaurs evolved to replace them as apex species of the seas. Some island-hopping dinosaurs, like Eustreptospondylus, evolved to cope with the coastal shallows and small islands of ancient Europe. Other dinosaurs, such as Carcharodontosaurus and Spinosaurus, rose to fill the empty space that the Jurassic-Cretaceous extinction had created. Of the most successful would be the Iguanodon which spread to every continent. Seasons came back into effect and the poles grew seasonally colder. Dinosaurs such as the Leaellynasaura inhabited the polar forests year-round, while many dinosaurs, such as the Muttaburrasaurus, migrated there during summer . Since it was too cold for crocodiles, it was the last stronghold for large amphibians, such as the Koolasuchus. Pterosaurs grew larger as species like Tapejara and Ornithocheirus evolved. More importantly, the first true birds evolved sparking competition between them and the pterosaurs.

The Late Cretaceous Epoch spans from 100-65 Ma ago. [24] The Late Cretaceous featured a cooling trend that would continue into the Cenozoic Era. Eventually, tropical ecology was restricted to the equator and areas beyond the tropic lines featured extreme seasonal changes of weather. Dinosaurs still thrived as new species such as Tyrannosaurus, Ankylosaurus, Triceratops and Hadrosaurs dominated the food web. Pterosaurs, however, were going into a decline as birds took to the skies. The last pterosaur to die off was Quetzalcoatlus. Marsupials evolved within the large conifer forests as scavengers. In the oceans, Mosasaurs ruled the seas to fill the role of the ichthyosaurs, and huge plesiosaurs, such as Elasmosaurus, evolved. Also, the first flowering plants evolved. [UKT ¶]

At the end of the Cretaceous, the Deccan Traps and other volcanic eruptions were poisoning the atmosphere. As this was continued, it is thought that a large meteor smashed into Earth, creating the Chicxulub Crater creating the event known as the K-T Extinction, the fifth and most recent mass extinction event, during which 75% of life on Earth became extinct, including all non-avian dinosaurs. Every living thing with a body mass over 10 kilograms became extinct, and the age of the dinosaurs came to an end. [25] [26]

The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India (17°–24°N, 73°–74°E) and are one of the largest volcanic features on Earth. - https://en.wikipedia.org/wiki/Deccan_Traps 180520
"The term "trap" has been used in geology since 1785–1795 for such rock formations. It is derived from the Scandinavian word for stairs ("trappa") and refers to the step-like hills forming the landscape of the region.^[4]
UKT 180520: These Deccan Traps and other volcanic eruptions would surely killed our giant lizards - Good riddance!

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2.3. Cenozoic Era

The Cenozoic Era featured the rise of mammals as the dominant class of animals, as the end of the age of the dinosaurs left significant evolutionary vacuums. There are three divisions of the Cenozoic:
#1. Paleogene Period
#2. Neogene Period 
#3. Quaternary Period

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2.3.1. Paleogene Period

The Paleogene Period spans from the extinction of the dinosaurs, some 66 Ma ago, to the dawn of the Neogene 23 Ma ago. It features three epochs:
#1. Paleocene Epoch
#2. Eocene Epoch
#3. Oligocene Epoch

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2.3.2. Neogene Period

The Neogene spans from 23.03-2.58 Ma ago. It features 2 epochs [32]:
#1. Miocene Epoch
#2. Pliocene Epoch

The Miocene Epoch spans from 23.03-5.333 Ma ago and is a period in which grass spread further across, effectively dominating a large portion of the world, diminishing forests in the process. [UKT ¶]

[In the sea,] Kelp forests evolved, leading to the evolution of new species, such as sea otters. [UKT ¶]

UKT 180521: Don't be misled by the term "Kelp forests". They are not terrestrial aka "land" forests. "Kelp forests" are marine forests of  giant sea-weeds. Birds fly between trees in land forests, but fishes swim among the giant sea-weeds. Land forests are lively in the daytime with songs of birds, whereas kelp forests are just gloomy worlds with nary a song of a bird!
See Wikipedia: https://en.wikipedia.org/wiki/Kelp_forest 180521

[On land,] During this time, perissodactyla thrived, and evolved into many different varieties. [UKT ¶]

UKT 180521: For perissodactyla , see Wikipedia: https://en.wikipedia.org/wiki/Odd-toed_ungulate 180521

Alongside them were the apes, which evolved into a 30 species. Overall, arid and mountainous land dominated most of the world, as did grazers. The Tethys Sea finally closed with the creation of the Arabian Peninsula and in its wake left the Black, Red, Mediterranean and Caspian Seas. This only increased aridity. Many new plants evolved, and 95% of modern seed plants evolved in the mid-Miocene. [33]

The Pliocene Epoch lasted from 5.333-2.58 Ma ago. [UKT ¶]

The Pliocene Epoch featured dramatic climactic changes, which ultimately led to modern species and plants. The Mediterranean Sea dried up for several million years. Along with these major geological events, Australopithecus evolved in Africa, beginning the human branch. The isthmus of Panama formed, and animals migrated between North and South America, wreaking havoc on the local ecology. Climatic changes brought savannas that are still continuing to spread across the world, Indian monsoons, deserts in East Asia, and the beginnings of the Sahara desert. [UKT ¶]

UKT 180521: On Indian monsoons, see Asian Monsoon and Cenozoic [Era] Tectonic History: Report of the Detailed Planning Group, May 2008, in TIL HD-PDF and SD-PDF libraries
- IodpOrganization-AsianMonsoonCenozoic<Ô> / Bkp<Ô> (link chk 180521)
UKT note: It is probable that uplift of the Tibetan Plateau and the Asian Monsoon are linked.

- https://www.nature.com/articles/s41598-017-16915-z
"The uplift of the Tibetan Plateau during the late Cenozoic [Erahad significant effects on both regional and global climate. They included the strengthening of monsoon systems, ..."

The Earth's continents and seas moved into their present shapes. The world map has not changed much since, save for changes brought about by the glaciations of the Quaternary, such as the Great Lakes. [34] [35]

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2.3.3. Quaternary Period

The Quaternary Period spans from 2.58 Ma ago to present day, and is the shortest geological period in the Phanerozoic Eon. It features modern animals, and dramatic changes in the climate. It is divided into two epochs:
#1. Pleistocene Epoch
#2. Holocene Epoch - 11.6 Ka ago to present

The Pleistocene Epoch lasted from 2.58 Ma (2580 Ka) to 11.7 Ka (11,700 years) ago. This epoch was marked by ice ages as a result of the cooling trend that started in the Mid-Eocene. [UKT ¶]

There were at least four separate glaciation periods marked by the advance of ice caps as far south as 40 degrees N latitude in mountainous areas. Meanwhile, Africa experienced a trend of desiccation which resulted in the creation of the Sahara, Namib, and Kalahari deserts. Many animals evolved including mammoths, giant ground sloths, dire wolves, saber-toothed cats, and most famously Homo sapiens. 100 Ka (100,000 years) ago marked the end of one of the worst droughts of Africa, and led to the expansion of primitive man. As the Pleistocene drew to a close, a major extinction wiped out much of the world's megafauna, including some of the hominid species, such as Neanderthals. All the continents were affected, but Africa to a lesser extent. That continent retains many large animals, such as hippos. [36]

The Holocene Epoch began 11.7 Ka (11,700 years ago) and lasts until to present day. [UKT ¶]

UKT 180521: I am interested in using Ka (thousands of years), is because the time of the Gautama Buddha - 2.5 Ka (ago). It is probable that a few of the giant animals such as giant birds might have remained, and the myths of Roc (of Sinbad the Sailor legend), Garuda and Naga of Indian legends might have been based on facts.

The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations: [13]
• Preboreal (10–9 Ka ago)
• Boreal (9–8 Ka ago)
• Atlantic (8–5 Ka ago)
• Subboreal (5–2.5 Ka)
• Subatlantic (2.5 Ka ago –present)

 

 

 

 

The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations:^[13]

 

 

All recorded history and "the history of the world" lies within the boundaries of the Holocene epoch.^[37] Human activity is blamed for a mass extinction that began roughly 10,000 years ago, though the species becoming extinct have only been recorded since the Industrial Revolution. This is sometimes referred to as the "Sixth Extinction". More than 322 species have become extinct due to human activity since the Industrial Revolution.^[38][39]

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UKT notes

Craton : Shield

- UKT 180517: Quote from Google: "The term craton is used to distinguish the stable portion of the continental crust from regions that are more geologically active and unstable. Cratons can be described as shields, in which the basement rock crops out at the surface, and platforms, in which the basement is overlaid by sediments and sedimentary rock."

From: https://en.wikipedia.org/wiki/Craton 180517

A craton, [1] [2] [3] from Greek: κράτος kratos 'strength', is an old and stable part of the continental lithosphere, where the lithosphere consists of the Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by younger sedimentary rock. They have a thick crust and deep lithospheric roots that extend as much as several hundred kilometres into the Earth's mantle.

The term craton is used to distinguish the stable portion of the continental crust from regions that are more geologically active and unstable. Cratons can be described as shields, in which the basement rock crops out at the surface, and platforms, in which the basement is overlaid by sediments and sedimentary rock.

The word craton was first proposed by the Austrian geologist Leopold Kober in 1921 as Kratogen, referring to stable continental platforms, and orogen as a term for mountain or orogenic belts. Later Hans Stille shortened the former term to kraton from which craton derives. [4]

Examples of cratons are the North China Craton, the Sarmatian Craton in Russia and Ukraine, the Amazonia Craton in South America, the Kaapvaal Craton in South Africa, the North American or Laurentia Craton, and the Gawler Craton in South Australia

From: https://en.wikipedia.org/wiki/Shield_(geology) 180517

A shield is generally a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. [1] In all cases, the age of these rocks is greater than 570 million years and sometimes dates back 2-3.5 Ga. [2] They have been little affected by tectonic events following the end of the Precambrian, and are relatively flat regions where mountain building, faulting, and other tectonic processes are greatly diminished compared with the activity that occurs at the margins of the shields and the boundaries between tectonic plates.

The term shield, used to describe this type of geographic region, appears in the 1901 English translation of Eduard Suess's Face of Earth by H. B. C. Sollas, and comes from the shape "not unlike a flat shield" [3] of the Canadian Shield which has an outline that "suggests the shape of the shields carried by soldiers in the days of hand-to-hand combat." [4]

Shields occur on all continents.

Go back Craton-note-b

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Siberia Paleocontinent

UKT 180516: Siberia is a part of Russia today. I've never known it to be a "continent" or "ancient continent (paleocontinent)".

From https://www.britannica.com/topic/Siberia-paleocontinent 180516

In Paleozoic Era: Paleozoic geography, Siberia, essentially the large Asian portion of present-day Russia, was a separate continent during the early and middle Paleozoic, when it moved from equatorial to northern temperate latitudes. Baltica moved across the paleoequator from southern cool temperate latitudes into northern warm latitudes during the Paleozoic.…  READ MORE

Paleozoic Era, also spelled Palaeozoic, major interval of geologic time that began 541 Ma ago with the Cambrian explosion, an extraordinary diversification of marine animals, and ended about 252 Ma ago with the end-Permian extinction, the greatest extinction event in Earth history. The major divisions of the Paleozoic Era, from oldest to youngest, are:
- Cambrian Period: 541-485.4 Ma ago
- Ordovician Period: 485.4-443.8 Ma ago
- Silurian Period: 443.8-419.2 Ma ago
- Devonian Period: 419.2-358.9 Ma ago
- Carboniferous Period: 358.9-298.9 Ma ago
- Permian Period: 298.9-252.2 Ma ago.
The Paleozoic takes its name from the Greek word for ancient life.

From: https://en.wikipedia.org/wiki/Siberia_(continent) 180518

Siberia, also known as Angaraland (or simply Angara) and Angarida, [1] is an ancient craton located in the heart of Siberia. Today forming the Central Siberian Plateau, it formed an independent continent before the Permian period.

Angaraland was named in the 1880s by Austrian geologist Eduard Suess who erroneously believed that in the Paleozoic Era there were two large continents in the Northern Hemisphere: "Atlantis", North America connected to Europe by a peninsula (= Greenland and Iceland); and "Angara-land", eastern Asia, named after the Angara River in Siberia. [2]

Go back Siberia-Paleo-note-b

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