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There are 3 different periods in the Mesozoic era, the Triassic period which was from 245-208 million years ago. The Jurassic period that was 208-144 million years ago. And lastly the Cretaceous period that is 144-66 million years ago

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There are many periods in the Palezoic era which contained the Cambrian, Ordoveion, Silurian, Devonian, Carboniferous, and Permian periods.

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The climate was hot and mostly dry. These conditions mostly ruled the center of the Pangaea (Pangaea is a super-continent, before the process of plate tectonics separated.

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North america separates from Africa and South Africa during the Jurassic period. During the Cretaceous period a widespread of volcanic activity occurs.

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During the Triassic the Pangaea hold together for much of the period. During the Jurassic period North america separates from Africa. During the Cretaceous period the continents start moving to their current positions. Also Africa and South Africa separate.

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During the Triassic period the age of reptiles begin, Dinosaurs start to appear and mammals that evolve from warm-blooded reptiles appear. Also crocodiles pop up. During the Jurassic period, the largest dinosaurs thrive such as the Stegosaurus, Diplodocus, and the Apatosaurus. The first birds appear. The first flying reptiles, pterosaurs appear. During the cretaceous period, Dinosaurs including the Tyrannosaurs Rex dominated. The first snakes appeared. The mass extinction that caused land and marine life to disappear happened at the end of the period.

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During the Triassic period conifers, palm-like trees, and ginkgo trees dominated the forest. During the cretaceous period, the first flowering plants appeared.

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-The Editors of Encyclopedia Britannica (2021) "Pangea Ancient super-continent" October 26, 2021 https://www.britannica.com/place/Pangea

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Table of Contents

How long ago did Pangea exist?

What is a supercontinent?

How did Pangea's formation affect life on Earth?

How did Pangea affect Earth's climate?

Pangea, also spelled Pangaea, in early geologic time, a supercontinent that incorporated almost all the landmasses on Earth. Pangea was surrounded by a global ocean called Panthalassa, and it was fully assembled by the Early Permian Epoch (some 299 million to about 273 million years ago). The supercontinent began to break apart about 200 million years ago, during the Early Jurassic Epoch (201 million to 174 million years ago), eventually forming the modern continents and the Atlantic and Indian oceans. Pangea's existence was first proposed in 1912 by German meteorologist Alfred Wegener as a part of his theory of continental drift. Its name is derived from the Greek pangaia, meaning "all the Earth."

Formation

The assembly of Pangea's component landmasses was well underway by the Devonian Period (419.2 million to 358.9 million years ago) as the paleocontinents Laurentia (a landmass made up of the North American craton-that is, the continent's stable interior portion) and Baltica (a landmass made up of the Eastern European craton) joined with several smaller microcontinents to form Euramerica. By the beginning of the Permian Period (298.9 million to 252.2 million years ago), the northwestern coastline of the ancient continent Gondwana (a paleocontinent that would eventually fragment to become South America, India, Africa, Australia, and Antarctica) collided with and joined the southern part of Euramerica (a paleocontinent made up of North America and southern Europe). With the fusion of the Angaran craton of Siberia to that combined landmass during the middle of the Early Permian, the assembly of Pangea was complete.

Geography

Pangea was C-shaped, with the bulk of its mass stretching between Earth's northern and southern polar regions. The curve of the eastern edge of the supercontinent contained an embayment called the Tethys Sea, or Tethys Ocean. The Paleo-Tethys Ocean took shape during Pangea's initial assembly phase. This ocean was slowly replaced by the Neo-Tethys Ocean after a strip of continental material known as the Cimmerian continent, or the Cimmerian superterrane, detached from northern Gondwana and rotated northward.

On the periphery of Pangea was Cathaysia, a smaller continent extending beyond the eastern edge of Angara and comprising the landmasses of both North and South China. Cathaysia lay within the western Panthalassic Ocean and at the eastern end of the Paleo-Tethys Ocean. Both oceans also contained scattered fragments of continental crust (microcontinents), basaltic volcanic island arcs, oceanic plateaus, and trenches. These island arcs and other isolated landmasses were later welded onto the margins of Pangea, forming accreted terranes (landmasses that collide with continents).

The assembly of the various large landmasses into the supercontinent led to the development of extensive dry climates in the supercontinent's tropics during Permian times. As low-latitude seaways closed, warm surface ocean currents were deflected into much higher latitudes (areas closer to the poles), and cool-water upwelling developed along Pangea's west coast. Extensive mountain-building events (or orogenies) occurred where the continents collided with one another, and the newly created high mountain ranges strongly influenced local and regional terrestrial climates. East-west atmospheric flow in the temperate and higher latitudes was disrupted by two high mountain chains-one in the tropics oriented east-west and one running north-south-that diverted warm marine air into higher latitudes.

These developments may have contributed to the series of extinction events that took place near the end of the Permian Period. Paleoecologists have posited that continental collisions eliminated several shallow-water marine basins-the primary habitat of most marine invertebrates-and Pangea's north-south orientation, which drastically changed ocean circulation patterns, altered regional climates. In addition, by the end of the Permian Period, land largely prevented cooler waters near the poles from entering the Paleo-Tethys and Neo-Tethys basins, which may have raised water temperatures in shallow areas above the tolerance limits of corals and other organisms ( see also Permian extinction).

Breakup

The mechanism for the breakup of Pangea is now explained in terms of plate tectonics rather than Wegener's outmoded concept of continental drift, which simply stated that Earth's continents were once joined together into the supercontinent Pangea that lasted for most of geologic time. Plate tectonics states that Earth's outer shell, or lithosphere, consists of large rigid plates that move apart at oceanic ridges, come together at subduction zones, or slip past one another along fault lines. The pattern of seafloor spreading indicates that Pangea did not break apart all at once but rather fragmented in distinct stages. Plate tectonics also postulates that the continents joined with one another and broke apart several times in Earth's geologic history.

The first oceans formed from the breakup, some 180 million years ago, were the central Atlantic Ocean between northwestern Africa and North America and the southwestern Indian Ocean between Africa and Antarctica. The South Atlantic Ocean opened about 140 million years ago as Africa separated from South America. About the same time, India separated from Antarctica and Australia, forming the central Indian Ocean. Finally, about 80 million years ago, North America separated from Europe, Australia began to rift away from Antarctica, and India broke away from Madagascar. India eventually collided with Eurasia approximately 50 million years ago, forming the Himalayas.

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Pangea | Definition, Map, History, & Facts

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Pangea, also spelled Pangaea, in early geologic time, a supercontinent that incorporated almost all the landmasses on Earth. Pangea was surrounded by a global ocean called Panthalassa, and it was fully assembled by the Early Permian Epoch (some 299 million to about 273 million years ago).

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During this era, The climate was warm. It was warmer than usual at 20 Celsius (68 Fahrenheit). Wet lands began to grow dry and trees grew on land.

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Mountains formed when the first early continents collided with each other. The sea levels rose up and fell over current north america. The super continent Pangaea forms as all early continents join together.

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In the early stages of the Paleozoic era, the early continents were slightly spread apart with north america in the middle of the equator. Nearing the end of the era, the super continent pangaea started to form as the early continents start to colide with each other.

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There are 3 periods in the Precombrian period, first there was the Haden period which was abour 4600 to 4000 million years ago. Next there was the Archean period which was from 4000 to 2500 million years ago. Lastly there was the Proterozoic period which was 2500 to 542 million years ago.

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Climate during the Haden period was it was very hot and there were a lot of toxic gases. During the Proterozoic period was cold and glaicers started to form.

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During the Precambrian period Earth begins to form, Oceans cover a vast amount of space. Also the first sediment rocks begin to form

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At the beginning of the Paleozoic era, There were many sea creatures. That was when fishes were developing over time such as them obtaining jaws or getting bigger which lead to the shark. nearing the end of the Paleozoic era, The first reptiles and insects appeared and the reptiles became dominant on land. But then, a mass extinction took out many marine invertebrates, including trilobites.

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During the Hadean period the earths crust was not formed. For most of the period, earth was under water. Since Earth was under water that means North America was under water.

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During the Precambrian era, bacteria appeared about 3.5 billion years ago. Soft bodied multicellular organsm developed in the late Precambrian. Also a mass extinction probably occurs near the end of the era.

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During the Precambrian era most of earth was under water. Becuase Earth was under water most of the plants were sea plants. One plant is called the Sea Pen.

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-Global Climate (2021) "Precambrian Era" October 28, 2021 https://www.climate-policy-watcher.org/global-climate-2/precambrian-era.html

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The precambrian era, or Supereon, refers to the geological time comprising the eons that came before the Phanerozoic eon. This time spans from the formation of Earth around 4.5 billion years ago to the evolution of abundant macroscopic hard-shelled animals, which marked the beginning of the Cambrian era, the first period of the first era of the Phanerozoic eon. The Precambrian era encompasses 86 percent of the Earth's history, however very little is known about this time period. In fact, the few fossil discoveries from this period were recently made in the late 20th century. Precambrian time can be further divided into three large eons, the Hadean, Archean, and Proterozoic eons.

The Precambrian's oldest eon, the Hadean (4.5 to 3.9 billion years ago), predates most of the geologic record. During the Hadean, the solar system formed out of gas and dust, the sun began to emit light and heat, and Earth took shape. Meteors and other galactic debris showered the planet over the first half-billion years, making it entirely uninhabitable. Planet Earth was very hot during its initial formation. As the earth began to cool and its mass increased, its gravitational field strengthened. This attracted meteorites and other debris, which continued to bombard the planet for at least another 500 million years, producing enough energy and heat to vaporize any water or melt any rock that may be present. Iron continued to sink to form the Earth's core, while silicon, magnesium, and aluminum gradually rose toward the surface. Gases released from magma inside the Earth escaped through cracks in the surface and began to collect in the early atmosphere. The likely presence of methane and ammonia among the gases made for conditions that would be highly toxic to life as we know it. Because there was little to no free oxygen, no protective ozone layers existed and damaging ultraviolet rays showered the Earth at full strength. As the meteorite bombardment finally slowed, Earth was able to cool, and its surface harden as a crust, rocks and continental plates began to form. Water began to condense in the atmosphere, resulting in torrential rainfall. After several hundred million years of falling rain, great oceans were formed. By about 3,900 billion years ago, Earth's environment had been transformed from a highly unstable state into a more hospitable place. This marked the beginning of the Archean eon (3.9 to 2.5 billion years ago). It was early in the Archaean eon that life first appeared on Earth.

Highlighted in light areas are Precambrian rocks. They formed between 560 million years and 2.6 billion years ago.

The climate of the late Precambrian time, the Pro-terozoic eon (2.5 billion years ago to 543 million years ago) was typically cold with glaciations spreading over much of the earth. One of the most important events of the Proterozoic was the gathering of oxygen in the Earth's atmosphere. Though oxygen was undoubtedly released by photosynthesis well back in Archean times, it could not build up to any significant degree until chemical sinks unoxidized sulfur and iron had been filled. The first advanced single-celled and multicellular life roughly coincides with the oxygen accumulation. It was also during this period that the first symbiotic relationships between mitochondria and chloroplasts and their hosts evolved. At this time the continents were bunched up in to a single supercontinent known as Rodinia. It broke up starting around 750 million years ago, and as continental fragments reached the North and South poles they likely contributed to the great Ice Ages. In the latest Proterozoic era a new supercontinent called Pannotia came together. A number of glacial periods have been identified going as far back as the Huronian epoch, roughly 2,200 million years ago. The best studied is the Sturtian-Varangian glaciation, around 600 million years ago, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth". This theory states that the continents and oceans were covered in ice approximately 600 million years ago. The Earth may have remained in this frozen form, but it was rescued by the release of volcanic gases. While the Earth was in a deep freeze, chemical cycles were halted; as a result, carbon dioxide accumulated in the atmosphere causing an extreme greenhouse effect. After 10 million years of deep freeze, the Earth thawed in only a few hundred years. These dramatic events may have caused the explosion of life-forms seen in Cambrian fossils.

At this point, at the start of the Cambrian period, Earth had taken on its current form in the life-filled oceans and oxygenated atmosphere. Coevolution of biosphere and lithosphere over billions of years led to this point. Anaerobes and oxygen-breathers had evolved complementary chemical cycles, and bio-genic carbonates entered the plate- tectonic cycle of the crust and upper mantle with new efficiency.

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Precambrian era - Global Climate - Climate Policy Watcher

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The precambrian era, or Supereon, refers to the geological time comprising the eons that came before the Phanerozoic eon. This time spans from the formation of Earth around 4.5 billion years ago to the evolution of abundant macroscopic hard-shelled animals, which marked the beginning of the Cambrian era, the first period of the first era of the Phanerozoic eon.

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In the early stages of the Paleozoic era, the plants grew under water. started off as sponges and progressed into psilophytes that later on grew into forests on land that started close to the end of the era.

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-Kheper Site(2002) "The Paleozoic" October 29, 2021 http://palaeos.com/paleozoic/paleozoic.html#:~:text=The%20early%20Paleozoic%20saw%20many,Baltica%20converging%20in%20the%20tropics.

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The Paleozoic Era of the Phanerozoic Eon: 542 to 251 million years ago

The Paleozoic (also spelt "Palaeozoic") era lasted from about 540 to 250 million years ago, and is divided into six periods The 320-odd million years of the Paleozoic era saw many important events, including the development of most invertebrate groups, life's conquest of land, the evolution of fish, reptiles, insects, and vascular plants, the formation of the supercontinent of Pangea, and no less than two distinct ice ages. The earth rotated faster than it does today so days were shorter, and the nearer moon meant stronger tides.

MAK

Since the continental cratons all move with respect to each other, we need to pick an East-West point of reference to keep things straight. Paleozoic paleocartographers have somehow fallen into the habit of placing this reference longitude slightly east of Greenland. For most of the Paleozoic, Greenland remained close to the equator and, after Baltica sutured to Laurentia North America plus Greenland) during the Silurian, this longitude came to correspond quite closely to the longitude of the future Greenwich, England, which defines the present conventional 0° longitude line. We will adopt this convention, although it is important to understand that it's just a convention. We have no absolute measures of East-West continental drift, and must be content with noting movements relative to some arbitrary geographical point.

The early Paleozoic saw many of the continents clustered around the equator, with Gondwana representing the bulk of old Rodinia) slowly drifting south across the South poles, and Siberia, Laurentia North America plus Greenland) and Baltica converging in the tropics. There was a large ocean between Laurentia and Eastern Gondwanaland.

It seems that Gondwanaland underwent a large clockwise rotation around an axis close to Australia during the Early Paleozoic. Laurentia underwent a large eastward movement, as well as a northward drift.

Baltica joined with Laurentia during the Silurian, drifting from a moderate southern hemisphere position in Cambro-Ordovician time to an equatorial position in Silurian-Devonian time. The combined continent is sometimes referred to as Euramerica, Laurasia, or Laurussia. Siberia, and possibly the Kazakhstan terranes, drifted across the equator to the northeast. All the East and Southeast Asian terranes, as well as the microcontinents which later formed Mexico, the east coast of North America, and southern Europe, were still part of the north coast (India-Australia margin) of Gondwana during the Early Palaeozoic.

During the middle and late Paleozoic ( Devonian to Permian), about a third of the Gondwanan mass was torn into small pieces and moved rapidly to equatorial regions. Most of these blocks were assembled by a series of plate collisions into the supercontinent of Euramerica by the Devonian, which by addition of further landmasses became Laurasia by the late Carboniferous. Most of western Gondwana (South America and Africa), then rotated clockwise and moved northward to collide with Laurasia. By Permian time, Siberia and the Kazakhstan terranes were sutured to Euramerica (Laurussia) and the Chinese blocks started accreting to them. The result was the supercontinent Pangaea. MAK, revised ATW050810.

MAK

The Cambrian climate was probably moderate at first, becoming warmer over the course of the period, as the second-greatest sustained sea level rise in the Phanerozoic got under way. However, as if to offset this trend, Gondwana moved south with considerable speed, so that, in Ordovician time, Most of West Gondwana (Africa and South America) lay directly over the South Pole. The Early Paleozoic climate was also strongly zonal, with the result that the "climate", in an abstract sense became warmer, but the living space of most organisms of the time -- the continental shelf marine environment -- became steadily colder. However, Baltica (Northern Europe and Russia) and Laurentia (eastern North America and Greenland) remained in the tropical zone, while China and Australia lay in waters which were at least temperate. The Early Paleozoic ended, rather abruptly, with the short, but apparently severe, Late Ordovician Ice Age. This cold spell caused the second-greatest mass extinction of Phanerozoic time.

The Middle Paleozoic was a time of considerable stability.Sea levels had dropped coincident with the Ice Age, but slowly recovered over the course of the Silurian and Devonian. The slow merger of Baltica and Laurentia, and the northward movement of bits and pieces of Gondwana created numerous new regions of relatively warm, shallow sea floor. As plants took hold on the continental margins, oxygen levels increased and carbon dioxide dropped, although much less dramatically. The north-south temperature gradient also seems to have moderated, or metazoan life simply became hardier, or both. At any event, the far southern continental margins of Antarctica and West Gondwana became increasingly less barren. The Devonian ended with a series of turnover pulses which killed off much of Middle Paleozoic vertebrate life, without noticeably reducing species diversity overall.

The Late Paleozoic was a time which has left us a good many unanswered questions. The Mississippian Epoch began with a spike in atmospheric oxygen, while carbon dioxide plummeted to unheard-of lows. This destabilized the climate and led to one, and perhaps two, ice ages during the Carboniferous. These were far more severe than the brief Late Ordovician Ice; but, this time, the effects on world biota were inconsequential. By the Cisuralian, both oxygen and carbon dioxide had recovered to more normal levels. On the other hand, the assembly of Pangea created huge arid inland areas subject to temperature extremes. The Lopingian is associated with falling sea levels, increased carbon dioxide and general climatic deterioration, culminating in the devastation of the end-Permian extinction.

Image: Devonian sea floor scene from the OTS Heavy Oil Science Center.

ATW041218. Text public domain. No rights reserved.

As one might expect from such a vast interval of time, there are a great many Paleozoic sites to choose from. Rather than attempt the impossible task of describing the scars left by 300 My of geological time, we thought we would briefly summarize the ten Paleozoic sites which, in our judgment, had left the greatest mark on paleontology. That, at least, is what we thought. As it turned out, after going through the agonizing job of paring down the list, we found that we could not get much below twelve or fifteen sites. Rather than make some kind of difficult, rational choice, we have simply hacked off the Permian and about half the Carboniferous, as well as randomly discarding some of the many Devonian sites. So you will not see anything from Isheevo or the Karoo, the red beds of Texas, Mazon Creek, Bear Gulch or even Canowindra. Some of these sites are covered in detail elsewhere on this site (which is, of course, one of the ten indispensible sites of Holocene time). Accordingly, without wasting a single electron or pixel more on vain regrets:

1) Chengjiang: Terreneuvian of South China. This site is discussed at Chenjiang. The English spellings are somewhat variable, "Chenjiang" being another popular variant. The correct spelling seems to be 澄江. It might be better to referred to as the Maotianshan Shale. This is less accurate (it is more properly the Qiongzhusi Formation), but seems least likely to be misspelled by ignorant foreigners, such as ourselves. The Chengjiang fossils are dated at 525-520 Mya, or perhaps a bit younger, corresponding most nearly to the Botomian Age in our system [1]. Outcrops of the Qiongzhusi occur in scattered locations south of Kunming in eastern Yunnan Province, Chengjiang County, near the towns of Chengjiang and Ercai. Additional sites have now been opened further south. Of all the sites mentioned here, Chengjiang is geologically the oldest and historically the youngest. The fossil potential of the region was discovered by Dr. Hou Xianguang in 1984. Many of the fossils have been recovered -- and many lost forever -- in connection with phosphate mines in the area. The incredible soft-tissue preservation of the fossils here seems to have resulted from rapid burial, complete sediment anoxia, and replacement of organic remains with pyrite or phosphates -- nothing magical, except the absolutely unreasonable number of such sites, of varying ages, in Yunnan Province.

The faunal list from Chengjiang is a virtually complete census of the major metazoan taxa of the time, and includes our personal favorite of all early chordates, Haikouella. There seems to be little selectivity. There are now Chengjinag fossil images all over the web. However, many of the Chengjiang organisms remain undescribed, simply for lack of competent describers, and new specimens are being discovered at an extraordinary rate.

2) The Burgess Shale: Middle Cambrian of Canada. The Burgess Shale is slightly younger than Chengjiang. The Shale is located near the town of Field, in southeastern British Columbia, high in the Canadian Rockies. The closest major town is Banff, about 90 km to the east. The site was discovered by Charles Walcott of the Smithsonian Institution in 1909, and the Walcott Quarry is named after him. The deposits are deepwater, benthic sediments, but the fauna probably represent a reef community swept off the reef and buried in an anoxic bottom by a mudslide. The Burgess is actually far less spectacular than Chengjiang, but it attained great fame (ironically, just at the time that Chengjiang was starting to produce large quantities of fossils) due in part to Jay Gould's book, Wonderful Life.

The Burgess Shale's influence on paleontology has been, in part, due to the fact that Gould chose this book to set out some of his most interesting and controversial ideas about evolution, and in a manner readable by almost everyone. Gould argued that the end results of evolution were essentially random because the process was chaotic [2]. Thus even the tiniest change in Proterozoic conditions might have resulted in an entirely different modern fauna. His proof was the diversity of phyla in the Shale, hinting at an enormous initial diversity in the Cambrian Explosion which was quickly pruned away, largely by happenstance. As it has turned out, Gould was certainly wrong about the Burgess Shale. Chengjiang -- and closer examination of the Burgess fauna -- have shown that Walcott was more correct than Gould. The great majority of Burgess animals can now be assigned with confidence to well-known phyla. However, his ideas about evolution may well be correct, if the pruning process actually occurred in the lower Early Cambrian or even before metazoans became morphologically recognizable.
Continued on Next Page

page uploaded on Kheper Site on 28 May 1998, page uploaded on Palaeos Site 9 April 2002,
checked ATW020714, last modified ATW041219

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The Paleozoic (also spelt "Palaeozoic") era lasted from about 540 to 250 million years ago, and is divided into six periods The 320-odd million years of the Paleozoic era saw many important events, including the development of most invertebrate groups, life's conquest of land, the evolution of fish, reptiles, insects, and vascular plants, the formation of the supercontinent of Pangea, and no less than two distinct ice ages.

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There are two periods in this era, the Tertiary period which was 66 million years ago and the Quaternary period which is 1.8 million years to the present.

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The climate is normally warm and moist, but it became cool and dry. There was also an ice age during the era.

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The rocky mountains and Himalayas form. Thick glaciers advance and retreat over much of North America and Europe parts.

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Continents continue to move into present day positions. Continental glaciers cover Antarctica. Continents continued the separation that had begun at the end of the Mesozoic Era.

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Age of Mammals begin. Modern groups such as horses, elephants, bears, rodents, and primates appear. Mammals and insects dominate the land. Giant mammals go extinct when the Ice Age ends.

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Flowering plants thrive. First grasses appear. Flowering plants dominate the land. Trees, grasses, shrubs, and other plants dominate many of Earth's biomes.

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Berggren, W. A. (2020, November 16). Cenozoic Era. Encyclopedia Britannica. https://www.britannica.com/science/Cenozoic-Era