The Mesozoic era it was the second era of the Phanerozoic Aeon. It began approximately 542 million years ago and ended 66 million years ago. It has been studied in depth by paleontologists, since it was in this era that the best-known animals of antiquity lived: dinosaurs.
Likewise, this era holds a mystery, the causes of which specialists have not yet been able to unravel: the mass extinction of the dinosaurs. During the Mesozoic Era, the planet became more habitable, both for plants and animals, even having characteristics similar to those it has today..
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The Mesozoic Era had an approximate duration of 185 million years distributed in three periods.
During this era the tectonic plates were very active. So much so that the supercontinent Pangea began to separate and form the different continents that are known today. Because of this the current oceans were formed.
The dinosaurs appeared and diversified, which had hegemony throughout the time that the era lasted. Here appeared the great herbivorous dinosaurs and the fearsome predators such as the Tyrannosaurus rex and the velociraptor. The dinosaurs dominated both the land and the water and the air.
At the end of the last period of the Mesozoic Era, a mass extinction process took place in which the dinosaurs disappeared.
According to specialists, the causes of this could have been several. The two most likely causes were the fall of a meteorite on the site where the Yucatan Peninsula is today and the intense volcanic activity..
There are many who believe that both could happen simultaneously. What is certain is that the climatic conditions of the planet changed significantly at the end of the Cretaceous period, which caused that very few species of living beings that existed could adapt.
The Mesozoic Era was found divided into three periods: Triassic, Jurassic and Cretaceous..
It was the first division of the era. It lasted approximately 50 million years. In turn, it was divided into three epochs: early, middle and late Triassic. Here the first dinosaurs appeared and the earth's surface was forming a single mass known as Pangea.
The second division of the era became known as the age of the dinosaurs. It lasted approximately 56 million years. It was divided into three epochs: early, middle and late. Here the great dinosaurs appeared and at a geological level the separation of the Pangea began.
Last period of the Mesozoic Era. It spanned approximately 79 million years, distributed in two epochs: Lower Cretaceous and Upper Cretaceous.
It was the time when great land predators such as the famous Tyrannosaurus rex existed. Likewise, the separation of the Pangea continued here. It culminated in the most well-known mass extinction process on the planet, in which the dinosaurs became extinct.
During the Mesozoic Era there were a lot of changes at the geological level. The activity of the tectonic plates was very intense, which caused the collision and separation of some of them. This in turn caused a rearrangement of the water masses that existed at that time..
At the beginning of the Mesozoic Era, all the supercontinents that had existed in later eras were forming a single land mass, which specialists called Pangea. Despite being a united mass, in the Pangea two well differentiated areas were distinguished:
This is how the earth's crust was at the beginning of the era. However, as time progressed and as a result of the friction of the tectonic plates, the supercontinent Pangea began to separate. This separation began during the first period of this era, the Triassic, and was further accentuated during the Jurassic.
As a result of this first fractionation of the Pangea, the two supercontinents mentioned above separated: Gondwana to the south and Laurasia to the north..
The most intense tectonic activity was recorded during the last period of the era, the Cretaceous. It was in this period that Laurasia and Gondwana separated in such a way that the resulting chunks of land closely resemble the continents that exist today..
Among the changes that the Gondwana supercontinent underwent at the end of the period, the following can be mentioned: South America separated from the African continent, Australia separated from Antarctica and began to move further north, India separated from Madagascar and moved further north. moved north towards the Asian continent.
During this period, from the orogenic point of view, there were no relevant episodes, except perhaps the formation of the Andes mountain range on the South American continent, caused by the tectonic activity of the South American and Nazca plates..
At the beginning of the period, there were only 2 oceans on the planet: the Panthalassa, which was the largest and surrounded the entire Pangea, and the incipient ocean Tetis, which occupied a small gulf at the eastern end of the Pangea..
Later, during the Jurassic period, the first signs of the formation of the Atlantic Ocean were seen. By the end of the era, the Pacific Ocean had already formed, which was what it is today, the largest ocean on the planet. The Indian Ocean also had its genesis in the Mesozoic Era.
At the end of the Mesozoic Era, the planet had a configuration very similar to the one it has today, in terms of oceans and land masses.
At the end of the Mesozoic Era, intense volcanic activity was recorded, specifically in the Cretaceous period, which was the last.
According to the fossil records and the analysis of specialists, it was in the area known as the Deccan plateau, in India, that this activity took place. There are lava flows from those eruptions.
Likewise, according to the information collected, the magnitude of these volcanic eruptions was such that even the lava in certain places could reach 1 mile thick. It is also estimated that it could have traveled distances as long as 200 thousand square kilometers.
These large-scale eruptions brought catastrophic consequences for the planet, so much so that they are even mentioned as one of the possible causes of the extinction process that occurred at the end of the Cretaceous period and the beginning of the Paleocene (Cenozoic Era)..
The volcanic activity that occurred in this era caused a large amount of gases, such as carbon dioxide (CO2), to be emitted into the atmosphere, as well as a lot of dust, ash and debris.
This type of material, which was kept in the atmosphere for a long time, is capable of reflecting sunlight. Because of this, the sun's rays could not reach the earth's surface..
This resulted in a considerable decrease in the temperature of the planet, which ceased to have the warmth and humidity that it enjoyed during the Triassic, Jurassic and much of the Cretaceous..
The planet became an inhospitable place that made it very difficult for the species that existed, especially the dinosaurs, to survive..
The climate during the Mesozoic Era varied in each of the periods that made it up. Despite this, it can be said that during almost the entirety of the era the climate was warm, with high temperatures.
At the beginning of the Mesozoic Era, the climate in the interior of the Pangea was quite arid and dry. This was so thanks to the immense size of this supercontinent, which caused much of its land to be far from the sea. It is known that in the areas near the sea the climate was somewhat milder than in the interior.
With the advance of time and the entrance to the Jurassic period, the level of the seas rose, which caused a change in climatic conditions. The climate became humid and warm, which favored the diversification of plants, causing a large number of jungles and forests to develop in this period in the interior of the Pangea..
During the late Cretaceous period the climate continued to be quite warm. So much so that, according to fossil records, the poles were not covered with ice. This indicates that temperatures across the planet must have been more or less uniform..
These conditions remained so until the end of the era. At the end of the Cretaceous period, the planet's temperatures dropped considerably, an average of 10 degrees. Scientists have several hypotheses as to why this happened.
One of these theories states that the intense volcanic activity surrounded the planet with a layer of gases and ash that prevented the penetration of the sun's rays..
The Mesozoic Era was characterized by several milestones regarding the development of life: in the botanical part, the first angiosperms (flowering plants) appeared, and in the zoological part, the diversification and predominance of dinosaurs.
Plant life forms were greatly diversified during the Mesozoic Era. During most of the era, the type of plants that dominated the landscape were ferns, which were quite abundant (especially in humid places), and gymnosperms, which are vascular plants (with conductive vessels: xylem and phloem) and are also seed producers.
At the end of the era, specifically in the Cretaceous period, flowering plants, known as angiosperms, made their appearance..
They represent the most evolved plants. Today they are the ones with the largest number of species. However, when they appeared in the Cretaceous period, they were found to a much lesser extent than gymnosperms..
The main characteristic of these plants is that their seeds are enclosed in a structure known as an ovary. This allows that seed to develop protected from external agents that can damage it. This simple fact constitutes a huge evolutionary advantage in reference to gymnosperms..
In the Mesozoic Era they were represented by three groups: the conifers, the benettitales and the cycads.
This type of plant is characterized because its seeds are stored in structures known as cones. Most of these are monoecious, that is, they present the male and female reproductive structures in the same individual..
Its trunks are woody and have evergreen leaves. Many of the forests that populated the planet were made up of conifers.
This group of plants are characterized by having woody trunks that do not have branches. Its leaves are located at the terminal end and can reach up to 3 meters in length..
They are dioecious plants, which means that there were individuals that possessed female reproductive structures and individuals that possessed male reproductive structures. Its seeds, covered by a material with a fleshy texture, were oval.
They were a group of plants that abounded during the Jurassic period of the Mesozoic Era. They became extinct at the end of the Cretaceous.
Two main genera are identified from this type of plant, the Cycadeoidea and the Williamsonnia. The former were small plants, without ramifications, while the specimens of the genus Williamsonnia were tall (2 meters on average) and did present ramifications. They were plants that closely resembled the cycads, so until recently it was considered that they belonged to this genus.
The fauna of the Mesozoic era was dominated by reptiles, mainly from the Jurassic period, and until the extinction of the late Cretaceous, dinosaurs were the dominant group.
Not only in the terrestrial habitat, but in the marine and the aerial one. Likewise, in the Jurassic the first birds and the first placental mammals appeared.
The skies of the Mesozoic Era were crossed by a large number of representatives of the reptilian group. They were able to acquire the ability to fly thanks to the fact that they developed a kind of membrane that stretched between the fingers of their front or rear limbs..
They ruled the skies throughout the Mesozoic Era. They appeared in the Triassic period and became extinct in the mass extinction process of the late Cretaceous.
Its main characteristic was its wings, which were a membrane that extended from the trunk to the fingers. This allowed them to plan and then learn to fly..
They were oviparous organisms, that is, they reproduced through eggs that developed outside the mother's body. Likewise, contrary to what might be thought, his body was covered with hair.
Its size could vary; There were them as small as a sparrow, even very large as the Quetzalcoatlus (whose wings had a wingspan of approximately 15 meters)
In terms of their eating habits, they were carnivores. They fed on other smaller animals, such as insects or even fish.
In terrestrial habitats, the predominant animals were dinosaurs. There were so small that they did not reach the meter of height, until the immense herbivores of the Jurassic. Likewise, some were carnivores, while others fed on plants.
In each of the periods that made up the Mesozoic Era there were characteristic and dominant dinosaurs.
Among the dinosaurs that dominated this period can be mentioned:
During this period the large herbivorous and carnivorous dinosaurs predominated, which have become so famous through dinosaur cartoons and movies. Some of them were:
The dinosaurs that existed here have also been highly recognized thanks to their appearance in movies and cartoons. Here are a few:
Life in the seas was also quite diverse during the Mesozoic Era. During the Triassic there were not as many vertebrates as in the Jurassic or Cretaceous. Here are some of them:
The invertebrate animal group also experienced some diversification during the Mesozoic Era. Among the phyla that stood out the most, we can mention the mollusks, being represented by gastropods, cephalopods and bivalves. There are abundant fossil records of the existence of these.
Likewise, in marine environments the group of echinoderms was also another edge that prospered, especially stars and sea urchins..
On the other hand, arthropods also had their representation in this era. There were some crustaceans, especially crabs, as well as butterflies, grasshoppers, and wasps.
Here it is important to mention that the emergence and development of angiosperm plants was linked to the development of certain arthropods that, as is well known, have an important role in the pollination process..
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