Wolfgang Korsus
Dipl.Ing. NT , Astrophysiker
Klingenberg 40
25451 Quickborn
TEL.: +49 4106 69295
Handy: +49 162 5680456
Website : wolfgang.korsus.net
FIVE TIMES THE WORLD HAS ALREADY GONE DOWN…….always accompanied by mass extinction
When I look at life, I realize that it is not just a slowly progressing model development or a simple improvement of individual series. If you look specifically at individual moments in the history of the earth’s history, I notice that sudden impacts also occur quite suddenly. I’m moving away from the word „impacts“ and calling it more accurately „catastrophes in Earth’s history“.
These changed life on earth or even almost wiped it out. What could have happened? „Suddenly“ indicates immediately. It gives the impression of being „very short in time“.
Let’s let the geologists speak for themselves. You characterize events that take place over a period of a few tens or hundreds of thousands of years as sudden events. When I look at the course of the development of life so far, I realize that this biological evolution flows like a continuous stream of air over the planet Earth.
To put it rather matter-of-factly, the formation of the Earth goes back 4.6 billion years: chronologically, these dates and facts show how a ball of embers turned into a flourishing place of life.
To put it in more detail, I come to this remark:
The history of the earth spans billions of years and is characterized by profound changes in geology, climate and biology. From the formation of the first continents and oceans to the unfolding of life in its present diversity, each phase of the Earth’s history has unique characteristics and events. This long and fascinating history of development is divided into four main eras: the Earth’s primeval age, the Earth’s ancient age, the Earth’s middle age and the Earth’s new age.
Over the course of these eons, the appearance of the Earth has constantly changed. Continental shifts shaped the geographic structure, while climatic fluctuations and geologic activities such as volcanism and earthquakes shaped environmental conditions. In the course of these changes, numerous species of flora and fauna have emerged and disappeared. Major extinction events (catastrophes) followed by phases of recovery and diversification characterize the course of evolution.
If you look at the catastrophes, it seems as if the survivors consume the remaining resources all the more unrestrainedly and thus develop considerably faster than they were able to before, under the existing pressure of their fellow populations. So I ask again, what events can trigger a mass extinction? OK ! The first thing that comes to mind is, of course, the threat from outer space. Defencelessly at the mercy of others. This leads us „astros“ to speculate that a gamma-ray burst could have hit the Earth around 450 million years ago. Because the very hard gamma radiation could have changed the atmosphere to such an extent that many living creatures on Earth died miserably. Because gamma-ray bursts are caused by a „hypernova“, for example.
It is considerably more powerful than a supernova. As you probably already know, this is a star that collapses under its own gravitational load at the end of its life and then explodes.
A hypernova is therefore a particularly powerful supernova with an electromagnetically emitted energy of more than 10⁴⁵ joules.
I would like to point out that a gamma-ray burst can occur. Nothing more than a gamma-ray burst. However, it is not super short, it lasts a relatively long time and roasts practically everything in its path. The ozone layer is also permanently damaged in the process.
Furthermore, the next mass extinction will take place. It’s called the Permian Event and by extension is directly related to the emergence of a species called Homo sapiens. We now know that this „mass extinction“ was the most violent of all those that have been or will follow. A good 90% of all species were affected. It was actually a complete extinction of life. Who was the trigger? Answer: it was plate tectonics, because this ensured that several …existing continents had already grown together to form a single large supercontinent.
Now an explanation must be found for what happened….. attempt has been made.
Something had moved, and movement has something to do with mechanics. But first the following. Radioactive elements decayed in the Earth’s interior, releasing energy. On top of this, or rather in addition, the residual heat from the formation of the Earth also provides energy. Let us summarize. So both cause the earth’s mantle to be hot and liquid.
I’ll just say 2 words now: movement/mechanics !!!
As a result, hot material constantly rises, cools down and partially sinks again-and this corresponds to convection.The lithospheric plates (consisting of a mosaic of tectonic plates of different sizes) floating on top and already cooled down considerably, moved back and forth on the water practically like bone-dry pieces of paper and bumped into each other. The heavy oceanic crust, which was constantly being formed, also rolled under the lighter continental plates. At the beginning of the 20th century, Alfred Lothar Wegener (* Nov. 1 in Berlin; † Nov. 1930 on Greenland) was a German meteorologist and polar and geoscientist. He already suspected this and it was actually proven in the sixties.
So it was 250 million years ago that the plate tectonics mentioned above led to the individual plates being joined together to form a large supercontinent. And the whole thing was surrounded by a huge sea.
But what does this constellation have to do with life on planet Earth? …. A good question…..Now, the climate in the interior of such a giant continent is more than dry as dust. The scientist says: an extremely arid place. As a result, the large number of living creatures there no longer had any water; …..irstly, but secondly….es was followed by a general climate change. A change in climate often has something to do with heat, yes, the air gets warmer and so does the water. Of course, the giant continent was also given a name:
Pangaea was as a primordial continent that encompassed all the land masses of the earth present in the „Permian“.
Then I say, PANGAEA. THE SUPERCONTINENT
So when all the „pre“ continents are united to form a supercontinent, this naturally has an effect on the climate: I can imagine that there were probably fewer irrigated coastlines and more dry areas in the interior of the continent…..
Biodiversity also declined drastically, because, as we know, warmer water can absorb less carbon dioxide!
Now, dear reader, your „CPU“ should surely be reporting something familiar!
The greenhouse effect
That’s right ! This greenhouse effect just described in the „Permian“ became stronger and stronger, which meant that it became even warmer.
Even less carbon dioxide was absorbed by the oceans and one more circumstance still drew attention to itself; these were the extreme, never-ending volcanic eruptions. They took place with gigantic liquid basalt flows. ….They poured over Siberia, India and Pakistan. All this meant that life on earth would have literally disappeared into oblivion by a „few millimeters“.
I consider this to be only a temporary phenomenon that took place 250 million years ago. But it should be noted: „Luck in misfortune“! There was still plate tectonics, because it ensured that this „giant supercontinent“ broke apart again. All the fracture plates became independent again, allowing new continents to form.
And these continents went, shall I say, completely their own way. I would like to take a closer look at just one of these „continental pieces of cloth“ that are on their way, and dear readers, please remain vigilant. Because this process turns out to have a meaning that I suspect some of you already know.
A continental plate, today we call it the Indian plate, what happened to it in the past? A curious question.
They were on the move at the time and with what an enormous „monkey-like“ speed. Speed. From a geological point of view, „monkey-like“ means that it sometimes moves several tens of centimeters per year and, of course, towards another plate. Now about the path? It raced through what is now called the Pacific and Indian Oceans. Now to the place, because the „where“ is also part of the lawn. I pick up the world map and recognize Eurasia.
I am pointing out this event for a good reason, because in the future it will be essential for the emergence of us, the species that is reading a few lines or even a whole book about the Anthropocene at this very moment. So please think a little longer about the Indian continental plate I mentioned.
Because I’m pointing in a very relaxed way to a „happening
far away, on the other side of the world“
➜ Yucatan in Mexico.
I’ll just say one word: „giant beasts“ ……. The dinosaurs dominate part of the earth, on water, on land and in the air. They are partly non-carnivores, omnivores and vegetarians. No one, or rather nothing, is safe from them.
But suddenly, as if out of the blue, there is a huge bang…….. and the next act in the spectacle of Earth’s history begins. Science has proven that 65 million years ago, an asteroid 10 to 15 kilometers in size crashed into the sea just off the coast of what is now Mexico, near the Yucatan Peninsula.
The speed of „it“, at a mere ten kilometers per second, many earth-threateners move like asteroids, but mostly – fortunately for us – past our earth.
But not this „bird“. It struck and released impact energies that far exceed our human imagination.
( Not even a large-caliber atomic bomb can compare with such a total destruction machine )
The asteroid impact I have just mentioned, it is hard to believe, has almost completely wiped out life, as is always the case when there has been a mass extinction in the history of the earth.
This was also the case here in Europe, in Asia, everywhere, globally. For a long time, efforts were made to investigate this. The dinosaurs, these enormous monsters or rather powerhouses, were even allowed to do without natural enemies. For this reason I emphasize that they were not all dead and gone in one day. In serious scientific terms, it will have taken a few hundred, probably even a few thousand years. How did they go about it? At first, people looked for traces of them in sediments.
Another of the many questions…….how do asteroid impacts show up in processed sediments after millions of years?
Answer:…….They reveal themselves through an extreme frequency of certain elements. Take iridium, for example. There is an iridium anomaly (irregularity, irregularity) that can be found all over the world in a thin, black layer of sediment and there, deep in the ground, are remnants of the special iridium. This only occurs in large quantities in asteroids. Is what has been said so far reasonably understandable? ….. If not, go on!
Sediment layers also contain a lot of soot and ash, but this is also found worldwide. What does this mean?
This means that parts of the earth’s surface are completely covered in dust and are cooling down.
A depressing scenario, some dust covers the ground and vast amounts of material have been thrown into the atmosphere. That means: goodbye sunbeams! They could no longer get through. A winter broke out. And it must have been exactly the same after the impact of the asteroid off Yucatan.
At the beginning, waves of detonations also ran over the earth with incredible pressure. They ironed down everything and everyone. But that wasn’t all, because there was also a 60-metre-high tsunami and fires everywhere. Summa Summarum……..If any living creature survived the (fire flood), it froze to death without a sound.
But that’s not all, food also became a big problem….At some point everything was eaten away, plants and prey alike.
I’m making myself something to eat at the moment. The thought of „eating“ makes me think of eggs!
Don’t laugh now, because when I think of eggs, it’s not just the edible chicken eggs………
……but dinosaur eggs. Yes, these are eggs that were used for the reproduction of this species. The reproduction of the dinosaurs was an egg thing, this reproduction also came to a standstill at that time (eggshells too thin)
I’m sure you can see from these facts that the cosmic impact and its consequences 65 million years ago marked a deep turning point in the history of life.
The „dinosaurs“ are among the biggest and best-known losers.
My final word is : They had left their last footprint !
Despite mass extinction, large (in the truest sense of the word) hunters have disappeared, but a „little animal dared to come out into the fresh air. It had been living on earth for several million years completely incognito.
➜ ➜ The triumphal march of the mammals began ➔ ➔
I have taken the liberty of mentioning the word mass extinction very often in my last posts and also explaining it ! For this reason, I will dwell on this subject a little.
In particular, it was always about the very sudden extinction of many, many species. It is actually the destruction of biodiversity through cosmic processes such as gamma radiation or the impact of large asteroids, through geological processes such as continental drift and volcanic activity. But every time something changes in the atmosphere, i.e. when important cycles are disrupted and thus collapse, i.e. when the „greenhouse effect“ becomes too strong or too weak, then the aforementioned mass extinction of many species occurs.
9I find it difficult, but it is necessary to inform you, dear readers, that we and our world are once again in the middle of an age of mass extinction. Because, as I have often said, it is we humans who shape an entire era. That is why the age named after us, the Anthropocene, hits the nail on the head.
This, our earth age, is also extremely characterized by mass extinction. Anyone who is well informed in the relevant media will hear and see every day that humans are currently destroying entire species in large numbers, in some cases even species that we have only just discovered or that we do not even know yet. If you look at the whole thing closely, you will notice that it is happening so quickly that you can even compare it to an asteroid impact in terms of its resounding effect. We humans are nothing other than a brain-burning social impact factor with an enormous potential for destruction that cannot be ignored.
When listing many striking dates, always remember the following:
Humans had not yet arrived, and there were no facts to indicate that they would make their appearance in the near future. Earth’s history speaks of other events.
So if we look at the BIG MASS ERADICATIONS that occurred about 2.4 billion years ago, it was the Great Oxygen Catastrophe triggered by cyanobacteria. It was precisely this that led to what was probably the most far-reaching mass extinction of the Precambrian. Most anaerobic life forms were wiped out. (In anaerobic energy metabolism, the body draws its power exclusively from carbohydrate reserves, without oxygen)
I’ll continue with a rather bored list:
Let’s go back down the road to where the past lies. The first station is 485 million years away, it is the end of the Cambrian. 80% of animal and plant species became extinct.
The reason for this was probably some sea level fluctuations.
Moving on, in the period about 450 million years ago, about 50 percent of all species disappeared in the Upper Ordovician. Here we can guess the probable cause of the first land plants that sprouted during this time, because they removed large amounts of carbon dioxide from the atmosphere and this resulted in a cooling of the global climate by about 5 ° C.
Some colleagues and I believe that a near-Earth hypernova and the resulting gamma-ray bursts destroyed life on Earth at the same time. It goes on to say that around 360 million years ago, 50 percent of all species became extinct in the Upper Devonian, including fish and trilobites (an extinct class of sea-dwelling arthropods), many reef-building cnidarian species also disappeared and with them numerous coral reefs. Scientists assume that only the oxygen content in the water dropped sharply (the oceanic anoxic event) and that only those animal species survived that were able to absorb oxygen outside the water. This means :
„The time of the amphibians had dawned“.
Then, about 250 million years ago, there was a period of 200,000 years during which the Permian mass extinction occurred:
Who or what died out ? I must or may ask this question. It is always very interesting to find out when another mass extinction took place. So let’s take a look :
About 95 percent of all species were in the oceans, plus more than 65 percent of all land dwellers (e.g. reptiles and amphibians). The question of who was responsible follows, and science probably points to the Siberian Trapp. This is a large igneous region formed from flood basalts. This was caused by huge volcanic eruptions and the release of large quantities of CO2.
All this together led to serious climate changes and the latest findings indicate that the Permian mass extinction can be divided into three phases.
The first phase, let’s call it the land phase, was caused by the Siberian Trapp, because it caused extreme climate change.
The result, the atmosphere warmed by about 5 ° C.
A little time passed and the warming also contributed to an increase in the temperature of the oceans. Very understandable, isn’t it?
Yes, marine life was severely shaken. A study published in 2015 revealed that ocean acidification may have played a significant role in the extinction of marine species. This is because the oceans absorb large quantities of atmospheric CO², which lowers their pH value. Which in turn means they become more acidic. A drop in the pH value of 0.6 to 0.7 is suspected, the result of the enormous CO² concentration.
These changes meant that marine organisms that build their shells or skeletons from calcium carbonate could no longer survive in the highly acidic environment.The rise in temperature in the oceans was not the only major „influencer“ on previous „planetary life“. No, its influence extends much further, even to chemical processes at the bottom of the oceans. It is highly probable that the rise in temperature has even broken down the chemical structure of the methane hydrate bound in the depths of the sea floor.
It is assumed that the methane trapped in the water molecules was released and rose naturally as a gas into the atmosphere, where it became more effective. This is about 20 times more effective than CO ². It made it even warmer (another 5°C). This was the „gong“ for the start of the third phase of species extinction.
Who else can I mention about the only known mass extinction of insects in the history of the earth?…..ja, it is a third of all insect species! If you compare all the mass extinctions of the Phanerozoic, the Permian was the largest.
And the bad news continues: a mere 200 million years ago, at the end of the Triassic, 50 to 80 percent of all species came to an end, including almost all terrestrial vertebrates. Again, this could be explained, the assumption is: the enormous magma releases before the break-up of Pangaea, as well as the poisoning of the shallow, warm marginal seas by large amounts of hydrogen sulphide because huge volcanic eruptions release large amounts of carbon dioxide and sulphur dioxide. We are now approaching the transition from the Mesozoic Era to the Modern Era (around 65 million years ago), when around 50 percent of all animal species died out again, including the dinosaurs with the exception of birds.
Again, a cause was suspected, but this time it was two events:
The impact of a meteorite near the Yucatan Peninsula and the continental eruption of a plume ( refers to a proposed upwelling structure for convection in the Earth’s mantle.
It took place in the Deccan Trapp (The Deccan Trapp in the Deccan region of western India is one of the largest regions on earth characterized by volcanism. It consists of a staircase-like I formation (Trapp) of flood basalt and today extends over an area of more than 500,000 square kilometers) in the Near East.
As far as the geological dates are concerned, we are working our way closer to the time in which we recognize ourselves as humans, according to …..?
The topic of cooling – something different. 34 million years ago there was a cooling of the global climate and again the associated „extinction of species“ reaches us. An even shorter time ago, around 50,000-12,000 years ago, a large part of the megafauna of America, Eurasia and Australia died out in the course of an extinction wave. A little less severe in its way, this mass extinction affected relatively few species. However, it still occupies scientists to this day, as many large, unusual and well-known animal species were involved, dear readers, I’m sure you’ve heard of it before
⏩ The mammoth, ⏩ the woolly rhinoceros and ⏩ the sabre-toothed tiger. The reasons for this wave of extinction, which occurred at different times on the individual continents, are highly controversial. Some assume that humans wiped out these large mammals through excessive hunting (overkill hypothesis). Other scientists, however, doubt this theory. They focus on the climate changes at the end of the ice age and consider these to be more likely causes. They assume that a reduction to human influences alone is rejected by large parts of the scientific community today. The latest evidence points to the impact of a meteorite, which is said to have reduced the number of large mammals to almost zero around 13,000 years ago. With regard to large mammals, reference should also be made to North America. There is a layer of earth called the „black mat“ in which there are no more deposits above the animals mentioned.
But now to the present, because this current wave of extinction is caused by humans and it began around 8,000 years ago in the Holocene and, listen up, hard-working readers, it continues to this day and is simply accelerating dramatically.
The hopefully well-known International Union for Conservation of Nature (IUCN) even assumes that the current extinction rate is 1,000 to 10,000 times higher than the so-called „normal“ rate.
Hear…hear !
I simply ask, can we actually compare the mass extinction that is now taking place with the previously mentioned events in past geological history? I consistently say
„NO“ …..denn completely different causes are responsible for „today“. Only we humans are responsible for this decline in biodiversity; the geological past has nothing to do with it. In the ‚Living Planet Report 2016‘, which I am sure you are familiar with, the environmental foundation World Wide Fund For Nature (WWF) speaks of a sometimes dramatic increase in the deterioration of the situation of many living species. It says: „For the period from 1970 to 2012, the global LPI (the Living Planet Index records the state of biodiversity on Earth) determined a decline in the population sizes of vertebrate species of an incredible 58 percent. The populations of vertebrate species have more than halved on average in around 42 years. The data show an average decline of 2.5 percent per year. The fact that there is absolutely no sign of this decline slowing down is purely appalling.
The LPI for species living specifically on land shows that populations have declined by a total of 42 percent between 1970 and 2029.
Let’s move on to the planet’s oceans, where populations have declined by 38 percent over the same period.
The loss of populations among animal species is dramatically high. For those living in freshwater, it is 83 percent for the period from 1970 to 2020. If we look specifically at the extinction rate of species then, as always, the alarm bell is ringing the loudest.
„Humans, who else, are causing and are responsible for the greatest global extinction of species since the disappearance of the dinosaurs, says Eberhard Brandes, WWF Germany. More than 23,000 species threatened with extinction have been on the WWF’s red list since the end of 2015. According to the organization, this is due to increasing poaching by mentally ill and money-hungry people. But far more serious are the changes to landscapes caused by humans. Not only animals and plants are disappearing, but entire ecosystems. It should also be noted that each of the species is „completely unique and therefore a value in itself“. The Red List always reports tragic data on species, but these have never before been listed and reported in their magnitude.
If, dear reader, the above seems a little too specific, complicated or boring for you, here’s everything in a nutshell for you to read and a little simpler in our CPU to refuel.
….also the repetition…. looks like this. ∰
Our planet „Earth“ was formed about 4.56 billion years ago. In its history on earth, it has gone through extremely different „epochs“.
A true marathon, because the history of the earth spans billions of years and is characterized by profound changes. These take place in geology, climate and biology. It began with the formation of the first continents and oceans and continued with the development of life in its current, „constantly choked“ diversity. Each phase of the Earth’s history has its own unique characteristics and events. Today, this enormously long and fascinating history of development is divided into four main eras: the primeval period, the Palaeozoic era, the Mesozoic era and the New Era.
In the course of these eons, the appearance of the earth has constantly changed. There were „continental drifts“, which shaped the geographical structure, while very influential climatic fluctuations and geological activities such as volcanism and earthquakes shaped the environmental conditions. We know that numerous species of flora and fauna emerged and disappeared in the course of these changes. Major extinction events followed by phases of recovery and diversification characterize the course of evolution.
The Precambrian laid the foundations for life on Earth, with the first simple life forms emerging. With the beginning of the Phanerozoic, which starts with the Cambrian, biological diversity increased dramatically. The following periods of the Palaeozoic, such as the Ordovician, Silurian, Devonian, Carboniferous and Permian, were characterized by the development of complex life forms, both in the sea and on land.
The Mesozoic era, comprising the Triassic, Jurassic and Cretaceous periods, was the era of the dinosaurs, which ultimately ended in one of the greatest mass extinction events in the history of the Earth. The Tertiary period of the Neozoic witnessed the rapid development of mammals and the emergence of the first hominids, while the Quaternary is characterized by the spread of man, his culture and civilization as well as dramatic climate change, including the ice ages.
The Earth’s history is thus a continuous narrative of change and adaptation, constantly shaping and reshaping the planet and its inhabitants. The ongoing scientific study of this past not only helps us to understand the complexity of life on Earth, but also offers insights into possible futures in a changing world.The Precambrian
The Precambrian marks the beginning of the Earth’s history and stretches from the formation of the Earth around 4.56 billion years ago to the beginning of the Cambrian around 541 million years ago. This extended period covers several eons: the Hadean, the Archean and the Proterozoic, the latter extending to the transition to the Phanerozoic.
During the Hadean period, the Earth and its first solid crust were formed. Life as we know it today did not yet exist in this phase. The beginnings of life can be seen in the following Archaic period, where the first simple life forms such as bacteria appeared. These microorganisms formed the basis for the further development of life on Earth. However, the origin and evolution of life remains an area of intense research and debate, with hypotheses such as the first life forms emerging from a „primordial soup“ or through panspermia being proposed .
The Proterozoic is characterized by significant geological, atmospheric and biological changes, including the appearance of the first multicellular organisms towards the end of this eon. Particularly noteworthy are the Ediacara fauna and the various glaciation periods known as „Snowball Earth“. These global glaciations and the subsequent warmer climate paved the way for the Cambrian explosion, a period in which a multitude of new life forms emerged within a relatively short period of time.
In order to stratify and examine the Precambrian more precisely, a division into different eons, eras and periods is proposed, which are defined on the basis of geological markers. These subdivisions range from the Hadean through the Archean with its various phases to the detailed Proterozoic, which is subdivided into the Paleoproterozoic, Mesoproterozoic and Neoproterozoic, each with its own characteristic features.
Studying the Precambrian remains a challenge, as fossils from this period are scarce and often provide only indirect evidence of the earliest life forms and their evolution. Nevertheless, the available geological and paleontological data provide a fascinating insight into the complexity and dynamics of the earliest history of the Earth and the beginnings of life on our planet.
The Cambrian
The Cambrian, a significant period in Earth’s history, extended from about 541 to 485.4 million years ago. This period is particularly known for the „Cambrian explosion“, a phase of explosive diversification of multicellular animal species in the sea, which led to the emergence of a large number of animal groups characterized by extraordinary morphological diversity, including many that still exist today.
Geologically, the Cambrian was characterized by the division of the supercontinent Pannotia into smaller continents, including Gondwana, Laurentia, Siberia and Baltica. These tectonic changes led to significant shifts in the continents and thus influenced the marine fauna by creating new ecological niches.
The climate of the Cambrian was warmer than today, with no ice at the poles, due to a high concentration of carbon dioxide in the atmosphere and a higher sea level. These conditions favored marine life and made the Cambrian explosion possible.
During the Cambrian, several mass extinctions occurred that caused significant changes in the biosphere. These extinction events led to the disappearance of a considerable number of species and had a profound impact on the evolutionary development of life on Earth.
The Cambrian period was characterized by a diversity of marine life, including early forms of sponges, cnidarians, arthropods and the first molluscs. This fauna formed the basis for the further evolutionary development of marine life. Despite the rich fossil evidence from the Cambrian, which documents an extraordinary diversity of life, the exact cause of the Cambrian explosion remains a subject of scientific research and debate.
The Cambrian was therefore a time of profound changes in the Earth’s history, which had a lasting impact on both the climate and the development of life on Earth and laid the foundations for the later development of biodiversity.
The Ordovician
The Ordovician, an epoch of the Palaeozoic, extended from about 485.4 to 443.4 million years ago and followed the Cambrian. It was characterized by significant geological, climatic and biological changes. The paleogeographic situation showed a continued drift of the continents. In particular, Avalonia drifted away from the northern edge of Gondwana and moved northwards, resulting in its own faunal province. Towards the end of the Ordovician, a large part of Gondwana froze over during the Hirnantian Ice Age, which also had an impact on the biodiversity of the time.
The climate of the Ordovician began with a CO₂ between 4000 and 5000 ppm, resulting in a warm or very mild climate. However, a global cooling, the Hirnantian Ice Age, led to the glaciation of large parts of the southern hemisphere, especially on Gondwana. These climate changes had a profound effect on the flora and fauna of the time.
The flora and fauna of the Ordovician comprised a wide variety of creatures, including the first land-dwelling plants and fungi. The sea was dominated by green algae, corals, sea urchins, mussels, arthropods, cephalopods and other echinoderms. Ordovician radiation led to the diversification and spread of these species. Conodonts, a group of early jaw-bearing animals, played a significant role in the marine fauna .
The Ordovician ended with one of the five largest mass extinctions in Earth’s history. Glaciation on Gondwana and the resulting cooling and sea level changes contributed significantly to this event. Despite hypotheses about possible triggers, such as near-Earth gamma-ray bursts, the rapid drop in temperature due to reduced volcanism and persistently high rates of weathering are considered to be the probable cause.
The recovery of biodiversity at the beginning of the Silurian marks the end of these massive environmental changes and the start of a new era of geological and biological development.
Silurian
The Silurian, a geological age that lasted from about 443 million years ago to 419 million years ago, marks a significant period in the Earth’s history, characterized by significant developments in flora and fauna as well as climatic changes.
During this period, the oxygen concentration in the atmosphere increased to around 14 percent for the first time, while the carbon dioxide concentration fell to below 4000 ppm towards the end of the Silurian. The climate was generally warm and temperate, with a global average of around 17°C, and the Earth was largely ice-free, resulting in high sea levels and the spread of shallow seas along the continental margins. These conditions favored the development of low-latitude reefs .
In the Silurian, biological diversity experienced a recovery and further development after the mass extinction of the Ordovician. Significant is the evolution of the first jaw-bearing vertebrates as well as the Placodermi and the first bony fishes. Sea scorpions reached a remarkable diversity and size during this period. Corals developed larger reef structures and blastoid echinoderms appeared for the first time.
Significant development also began on land. The first vascular plants, such as Cooksonia and Baragwanathia, appeared in the Middle Silurian, marking a turning point in the colonization of the mainland. These early land plants were characterized by a simple structure without differentiated roots, stems or leaves and reproduced via spores. In addition, the first recorded lichens, which represent a symbiotic relationship between algae and fungi, are known from the Silurian.
Geologically, the arrangement of the land masses remained similar to the Ordovician, with the supercontinent Gondwana slowly drifting over the South Pole and other continents moving towards their present-day positions. The Silurian was characterized by large-scale limestone deposits, especially in the later developing mountainous regions of Scotland, Sweden and Norway.
In summary, the Silurian was a time of climatic transition and biological diversification, laying the foundations for further evolutionary development and reflecting the increasing complexity of life on Earth.
The Devonian
The Devonian, which spans a period from about 419.2 million years ago to about 358.9 million years ago, was a period of profound evolutionary, geological and climatic change . This era, also known as the „Age of Fishes“, saw the development of an enormous diversity of fish species, including armored fish (Placodermi), spiny sharks (Acanthodii), coelacanths and lungfish, which are considered the precursors of later vertebrates. Dunkleosteus, a predatory armored fish, stood out as one of the largest known sea creatures of its time .
In addition to marine biodiversity, the Devonian marked important advances in the colonization of the mainland. The first recorded land vertebrates (tetrapods) such as Ichthyostega and Acanthostega, which had an amphibious lifestyle, made their appearance. These developments suggest that the ancestors of Devonian tetrapods may have evolved from coelacanths .The Devonian flora also underwent significant expansion and diversification. The first vascular plants, including Rhynia and other ancient ferns and lycopods, spread and laid the foundations for the formation of the world’s first forests. This plant expansion had a significant influence on the atmospheric composition, especially on the oxygen content, which rose to around 35 percent in the Carboniferous.
Geologically, the Devonian was characterized by the collision of Gondwana with Laurussia, which led to the closure of the Rheic Ocean and formed the basis for the Variscan orogeny. These tectonic activities helped to shape the paleogeographic and climatic conditions that characterized the Devonian. The Devonian climate was generally warm and dry, with higher sea levels and smaller temperature differences between the poles and the equator compared to today.
The end of the Devonian was marked by several mass extinction events, including the Kellwasser and Hangenberg events, which greatly reduced marine biodiversity and caused profound changes in ecosystems. These events formed the transition to the next geological period, the Carboniferous .
The Carboniferous
The Carboniferous, a geological period of the Paleozoic, extended from about 358.9 to 298.9 million years ago. This epoch follows the Devonian and is succeeded by the Permian. The Carboniferous is particularly known for its rich coal deposits, which were formed by extensive forests and marshlands. This vegetation played a major role in lowering the concentration of carbon dioxide in the atmosphere and contributed to a significant increase in oxygen levels, reaching local concentrations of up to 40 percent at peak times .
The palaeogeographic situation was characterized by the progressive convergence and collision of the Laurentia and Gondwana continents, which eventually led to the formation of the supercontinent Pangaea. These plate tectonic movements triggered the Variscan orogeny, which led to the formation of large mountain ranges in Europe and the closure of the Rhine Ocean.
The climate in the Carboniferous was initially characterized by a warm climate, but this changed over time into a Permo-Carboniferous ice age, characterized by glaciations in the land masses of Gondwana south of the Arctic Circle. These climate changes had profound effects on the environment and the biosphere, including a marked alternation of warm and cold periods.
The fauna of the Carboniferous underwent significant developments, particularly with the landfall of vertebrates. Tetrapods, including the first amphibians and reptiles that no longer relied on aquatic habitats for reproduction, played a central role in this process. These developments enabled an increasing diversification and complexity of terrestrial ecosystems .
Also noteworthy is the size of some arthropods during the Carboniferous, which reached gigantic proportions in the oxygen-rich atmosphere, such as dragonflies with wingspans of up to one meter and large scorpions.
In the oceans, sharks dominated the top of the food chain, while spiny sharks played an important role in freshwater systems. The development of marine fauna was also reflected in the diversification of ammonoids and an increase in foraminifera.
The Carboniferous also marks a crucial phase in the evolution of flora with the strong radiation of horsetails, ferns and later the first gymnosperms. These plants formed the first extensive forests that shaped the Earth and led to increased oxygen production .
An outstanding event at the end of the Carboniferous was the Carboniferous Rainforest Collapse (CRC), a dramatic extinction event that caused the large primeval forests and parts of their fauna to disappear and led to a decline in global biodiversity .
The Permian
The Permian, the last geological period of the Palaeozoic, stretched from around 298.9 million years ago to 251.9 million years ago and resulted in the largest known mass extinction in the history of the earth. This epoch marked a time of profound environmental change, evolutionary development and ended with a dramatic event that nearly wiped out life on Earth.
Climatically, the Permian was characterized by persistent glaciation phases of the southern continents, which lasted well into the Permian and resulted in a dry and sometimes cool climate in many areas. Only after the retreat of the glaciers did a warm climate stabilize. Nevertheless, the period was characterized by extreme climatic fluctuations and the formation of the richest salt deposits in the Earth’s history.The flora adapted to the cooler climatic conditions, with an advance of Glossopteris flora in the southern latitudes, while the vast desert areas of Pangaea posed a challenge for vegetation. Towards the end of the Permian, gymnosperms dominated the landscape and increasingly replaced the previously dominant ferns and lycopods.
On the faunistic side, the Permian was dominated by the amniotes, which include both the early reptiles and the precursors of today’s mammals, the therapsids. These groups benefited from their independence from aquatic reproduction methods and colonized new habitats on land. Synapsids in particular flourished and rose to become dominant predators before being severely decimated at the end of the Permian .
The end of the Permian was initiated by volcanic activity in what is now Siberia and the associated catastrophic climate changes. The mass extinction at the transition to the Triassic decimated around 96 percent of all marine life and around 75 percent of land creatures. This event left behind a world that took millions of years to recover from the devastation.
Overall, the Permian is a period of change and contrasts, characterized by climatic extremes and biological diversity, culminating in one of the most dramatic mass extinctions in Earth’s history.
The Triassic
The Triassic marks the beginning of the Mesozoic era, some 252 million years ago, and lasted around 50 million years. During this epoch, the supercontinent Pangaea united almost all land masses, which had a profound impact on climate, ocean currents and the distribution of flora and fauna. One of the most remarkable developments of this period was the emergence of the first dinosaurs, which were characterized by their initially small size and completely carnivorous diet. By the end of the Triassic, the dinosaurs had diversified and dominated the planet as vertebrates.
Geologically, the Triassic was characterized by the existence of Pangaea, which led to the formation of enormous desert areas inland. The late Triassic was characterized by the beginning of the breakup of this supercontinent, which eventually led to the formation of Laurasia and Gondwana. The beginning of these tectonic shifts gave rise to new ocean currents and led to a slight rise in sea level.
The Triassic climate was generally warm and dry. The extensive land masses of Pangaea favored the development of large desert regions and a continental climate with extreme temperature fluctuations. This in turn had an influence on the vegetation and the animal world. In the polar regions, despite the high temperatures, there were wetlands with a temperate climate, which encouraged the spread of reptiles.
The Triassic flora and fauna were characterized by a significant recovery and diversification after the massive extinction at the end of the Permian. The plants were dominated by seed ferns and the first gymnosperms, while the animals were dominated by dicynodonts, a group of therapsid herbivores, and various archosaurs, including the first dinosaurs. At the end of the Triassic, however, there was another mass extinction that brought many of these developments to an abrupt end and paved the way for the dominance of the dinosaurs in the following Jurassic.
The stratigraphic structure of the Triassic is based primarily on ammonoids and other key fossils such as conodonts and shells, which provide important insights into the biological and geological changes of this era. This period of upheaval and new developments formed a decisive phase in the history of the earth, the consequences of which extended into the Jurassic and had a significant influence on evolution on our planet.
The Jurassic
During the Jurassic period, which lasted from about 201.3 to 145 million years before our era, the Earth experienced a phase of extensive tectonic activity and biological development. The Jurassic period is known for the dominance of dinosaurs, which evolved into a great diversity and adaptability during this time. Prosauropods evolved into the giant sauropods, while theropods such as Allosaurus and the first birds, including the famous Archaeopteryx, emerged.
The palaeogeographical configuration was characterized by the supercontinent Pangaea, which gradually began to separate into Laurasia and Gondwana. This tectonic dynamic led to the formation of new marine and terrestrial ecosystems and the diversification of fauna and flora. Significant sea level fluctuations and volcanic activity, particularly due to the Karoo-Farrar magma outflows, characterized the era. The climate in the Jurassic was on average warmer than today, with temperatures of around 16.5 degrees Celsius and an oxygen content in the atmosphere that was about a third higher than today’s norm.
The flora was dominated by gymnosperms such as conifers and ginkgo trees, while dinosaurs played a central role in the fauna. The mammals, including Castorocauda, resembled beavers and show the progressive evolution of this group during the Jurassic. The Jurassic period ended with a smooth transition into the Cretaceous period, characterized by a further phase of biological and geological changes.
The Cretaceous
The Cretaceous period, the last period of the Mesozoic era, lasted from around 145 million to 66 million years before present and ended with one of the most dramatic mass extinctions in Earth’s history. During this era, a significant evolution of fauna and flora took place, with dinosaurs as the dominant land dwellers and the emergence of the first flowering plants.
Palaeogeography was characterized by the progressive disintegration of the supercontinent Gondwana, which led to a reshaping of the continental arrangement and the formation of new oceans. Europe was dominated by shallow seas, some of which were exposed again by tectonic activity and uplift processes during the Cretaceous period. Significant volcanic events, such as the formation of the Deccan Trapps, contributed to the mass extinction at the end of the Cretaceous period.
The climate in the Cretaceous period was generally warm and experienced a peak in global temperatures, which led to ice-free poles, among other things. Sea levels were high, which favored the formation of extensive shallow marine zones. Nevertheless, towards the end of the Cretaceous there was a cooling phase that led to a marked regression.
The flora experienced a revolution with the emergence of angiosperms. These flowering plants spread rapidly and became the dominant plant group. In addition to flowering plants, tree ferns, ginkgos, conifers and the first grasses also shaped the landscapes of the Cretaceous period. This development of the plant world in turn had an influence on the diet and ecosystem of the dinosaurs and other creatures.
In the fauna, dinosaurs continued to dominate the terrestrial ecosystems. In addition to the well-known groups of spinosaurs and carcharodontosaurs, tyrannosaurs also developed into important predators. The sea was home to mosasaurs and other marine reptiles. Cretaceous mammals began to develop greater ecological diversity, but remained in the shadow of the dinosaurs until the mass extinction at the end of the Cretaceous, which paved the way for the dominance of mammals in the Cenozoic.
The end of the Cretaceous was marked by the mass extinction triggered by the Chicxulub meteorite impact, which resulted in the demise of the dinosaurs and many other species. This event heralded the transition to the Cenozoic, the age of mammals.
The +Tertiary
The Tertiary, a geological period that began around 65 million years ago and lasted until around 2.6 million years ago, marks a significant section of the Earth’s modern history. It covers the Paleogene and Neogene periods and follows the mass extinction at the end of the Cretaceous, which led to the disappearance of the dinosaurs. This event opened up new evolutionary possibilities for mammals, including the first ancestors of humans.
During the Tertiary, major mountain ranges such as the Alps, the Andes and the Himalayas were formed by the collision of tectonic plates. These geological changes had far-reaching effects on the climate and the distribution of flora and fauna. The shifting of the continents led to a gradual reshaping of the geographical landscape that would shape the modern world.
The Tertiary climate was characterized by an initial warming that provided ideal conditions for the evolution of mammals. Over time, however, cooling occurred, which eventually led to the glaciation of the northern continents. The flora and fauna of the Tertiary period developed in a variety of ways against this background. In addition to the first flowering plants that spread around the world, new species of mammals emerged that took on dominant roles both on land and in the water. Predators, primates, ungulates and many other mammalian groups diversified during this period.
The emergence and development of the first human-like ancestors, including genera such as Proconsul and Australopithecus, is another outstanding feature of the Tertiary period. These early hominids laid the foundation for the later development of modern humans. The Tertiary ended with the transition to the Quaternary, which was characterized by the continuation of cooling and the spread of ice sheets.
Quaternary
The Quaternary, the most recent period in the Earth’s history, began around 2.6 million years ago and continues to the present day. This period is particularly characterized by the presence of humans and their evolutionary development, as well as by pronounced climatic fluctuations that led to several ice ages.
The Quaternary is divided into two main phases: the Pleistocene, which began around 2.58 million years ago and lasted until around 11,700 years ago, and the Holocene, which has continued since then until today. The Pleistocene is characterized above all by the ice ages, while the Holocene is a phase of relative climatic stability and warmth.
The development of humans, beginning with the appearance of Homo habilis and progressing through Homo erectus to modern Homo sapiens, represents one of the most significant aspects of the Quaternary period. These developments include physical evolution as well as the beginning of tool production and cultural development.
In addition to human development, the fauna experienced significant changes that were influenced by the climatic fluctuations of the Quaternary. Many species migrated, adapted to new conditions or became extinct. The flora also underwent adaptations, with the spread of grasses and the development of forests rich in ash, beech, elm and fir trees.
The Quaternary is also characterized by significant geological changes, including the shaping of today’s continental and oceanic landscapes and the formation and retreat of large ice masses. These changes had a profound impact on living conditions on Earth and shaped the natural environment in which human civilization emerged and evolved.