MESOZOIC ERA : THE AGE OF DINOSAURS
From the origin of the first life on Earth to the present day, the planet has already experienced several eras of development. One epoch replaced the other, and this was directly related to climate and crust changes. Today we want to tell you about an era called Mesozoic, or as it is called, the age of reptiles. In the evolutionary process of life on Earth, this era is ranked fourth in order.
That's the era of tectonic, climatic, and evolutionary activity. The basic contours of the modern continents are being formed and urban formation is taking place on the periphery of the Pacific, Atlantic, and Indian oceans; land division has contributed to species formation and other important evolutionary events. Mesozoic began 250 million years ago, and its duration is 183 million years.
What periods make up the Mesozoic Era?
Scientists tend to distinguish three main periods: Triassic, Jurassic, and Cretaceous.
- The Triassic period (Trias): The initial period of the Mesozoic era, which lasted 35 million years. At that time, the Atlantic Ocean was being formed. The single continent of Pangaea again began to break into two parts, Gondwana and Laurasia. Inland waters begin to actively dry up, in their place new mountains and volcanoes appear. A huge part of the land is still occupied by desert areas with weather conditions that are unsuitable for most species of living creatures. Salt levels in water bodies are rising. During that time, birds, mammals, and dinosaurs appear on the planet.
- The Jurassic period (Jura): This is the most famous period of the Mesozoic era. It is the average period of the Mesozoic era, which lasted about 69 million years. At this stage begins the formation of modern continents - Africa, America, Antarctica, and Australia. But they are not yet in the order we're used to. Deep bays and small seas separating the continents appear. The active formation of mountain ranges continues. The sea of the Arctic is flooding northern Laurasia. As a result, the climate is humidified and vegetation is formed in place of deserts.
(Interesting fact! - The Jurassic period was named after the sedimentary deposits of that time found in the Jura (European mountain ranges))
- The Cretaceous period: This is the final period of the Mesozoic era occupies a period of 79 million years. Covered seed plants appear in the Mesozoic period. As a result, the evolution of the fauna begins. The continents continue to move - Africa, America, India, and Australia are distant from each other. The continents of Laurasia and Gondwana are beginning to break up into continental blocks. Huge islands are forming in the south of the planet. The Atlantic Ocean is expanding. The Cretaceous period is a time when flora and fauna on land flourish. Due to the evolution of the plant world, fewer minerals get into the seas and oceans. There are fewer algae and bacteria in the aquatic world.
Where were the continents during the Mesozoic Era?
At the beginning of the Triassic period (240 million years ago) all the main landmasses were soldered into one super-continent - Pangaea, two parts of which - Laurasia in the North and Gondwana in the South - were washed by the waters of the huge Tethys Ocean.
Subsequently, in the Jurassic period, Pangaea began to disintegrate. A wide strait opened between the southern supercontinent Gondwana and the northern supercontinent Laurasia, part of which was flooded. Gondwana also split: South America and Africa were separated from India, Antarctica, and Australia. Both the North and South poles were in oceanic areas.
(Interesting fact! - In the Mesozoic era, the Tethys Ocean was experiencing a restless time. Its shores were lowered, sometimes submerged and then whole mountain systems rose again. These events were caused by the urban formation processes along the northern shores of the Tethys Ocean. They are known in Dobruja, the Crimea, the Caucasus, the Pamirs, and several other areas. Diving, which reached a large scale, was often carried out in Jurassic times.)
What was the climate like during the Mesozoic Era?
The climate of the Mesozoic era is characterized as relatively warm. The air temperature at the equator and the poles were kept at the same level. At the end of the first period of the Mesozoic era, drought prevailed for most of the year and was briefly replaced by rainy seasons. Deserts and semi-deserts covered Europe and North America. The regions of Siberia and Indochina had a more humid tropical and subtropical climate. As marine transgressions progressed, global climate conditions softened. The Jurassic period, which began 200 million years ago, was characterized by a warm climate around the globe. The average temperature has again reached 24.5 °C. Even in today's Arctic, it was warm. Water temperature in areas of modern Great Britain and Denmark reached +21 °С in the early Jurassic and late Jurassic it increased to +28 °С. No evidence of widespread glaciation in Jurassic times has been established. East Antarctica occupied the most northern position, so if there are traces of Jurassic glaciation, they should be sought in the territory now occupied by the Antarctic ice cover.
However, a warm climate was not present on the planet throughout this era.
At the end of the Mesozoic era, the climate became colder in the Cretaceous. All continents have their climate. Tree plants appear, which lose their leaves in the cold season. Snow begins to fall at the North Pole. Some species of reptiles are adapting to climate change and cold weather. From these species, mammals and birds will come later.
What lived during the Mesozoic Era?
In the Mesozoic era, tectonics and climate change caused the rapid development of flora and fauna. New species of living organisms and plants appeared and actively developed, replacing, and displacing older species.
At the beginning of the Mesozoic, the continents were reigning lycopodium, various ferns, the ancestors of modern palms, conifers and ginkgo trees. In the seas and oceans, the reef-forming algae dominated. The high humidity of the Jurassic climate led to the rapid formation of the planet's vegetation mass. Forests consisted of ferns, conifers, and cicadas. Thujas and araucarias were growing near water. Two belts of vegetation were formed in the middle of the Mesozoic era: The northern belt, dominated by herbaceous ferns and ginkgo trees; Southern. Tree fern and cicada trees reigned here. There were practically no differences in horsetails, lycopodium, Coniferous forest areas of this time interval are very similar to the modern ones. They include yews, firs, and cypresses. Some trees dump their leaves during the winter.
The Cretaceous period is characterized by the appearance of plants with flowers. In this connection, butterflies and bees appeared among the insects, thanks to which flowering plants were able to spread quickly on the planet. And, as these plants can adapt to any weather conditions and develop rapidly, it allowed them to spread throughout the Earth in a short time. Their variety of species and shapes have also reached the modern world - eucalyptus, magnolias, quince, oleanders, nut trees, oaks, birches, willows, and beeches.
As for the animal world of Mesozoic...
The most widespread was the Mesozoic reptiles, which became a truly dominant class in this era. In the process of evolution, a variety of species and kinds of reptiles appeared, from small - the size of a chicken, to giant - up to 30 meters long and weighing several tens of tons.
During the Triassic period, many new groups of reptiles emerged. These are turtles and well adapted to life in the sea Ichthyosaurs, externally resembling dolphins, Placodontias, and Plesiosaurs living in the sea.
During the Jurassic Plesiosaurs and Ichthyosaurs, they reached their golden days. Both groups remained very numerous even in the early Cretaceous period, being extremely characteristic predators of the Mesozoic seas. From an evolutionary point of view, one of the most important groups of Mesozoic reptiles was the Thecodontia, small predatory reptiles of the Triassic period, which gave rise to almost all groups of terrestrial reptiles of the Mesozoic era: crocodiles, dinosaurs, flying lizards and, finally, birds. The most unique group of Mesozoic reptiles were well-known dinosaurs. They developed out of Thecodontia and immediately identified their leading positions. Dinosaurs evolved and developed throughout the Mesozoic era, and each period was characterized by its outstanding dinosaur species (which we will talk about in the next articles).
The Mesozoic era was also represented by an abundance of other reptiles, besides dinosaurs. For example, the first crocodiles that appeared in the Triassic period (Steneosaurus, etc.). In the Jurassic period, flying lizards appeared - Pterosaurs (Pterosaurid), also derived from Thecodontia. Among the flying lizards in the Jurassic, the most famous are Ramphorhynchus and Pterodactylus, the relatively large Pteranodon is the most interesting of the Cretaceous forms. Flying lizards extinct by the end of this period.
In the Cretaceous Seas, giant predatory lizards, Mosasaurs, exceeding 10 m in length, have become widespread. Among modern lizards, they are the closest to varans, but differ from them, in particular, the finned limbs. By the end of the Cretaceous, there were also the first snakes (Ophidia).
The aquatic fauna was also rich. For example, there existed the ancient cephalopods from which modern squid and octopus evolved. The Mesozoic representatives of this group included ammonites with a shell wrapped in a "sheep's horn" and belemnites, the inner shell of which had a cigar-shaped shape and grew into a body pulp - a mantle. It was in Mesozoic that ammonites reached their highest diversity. Only in Triassic, there were over 400 new births of ammonites. Among the brightest representatives are individuals from the groups Phylloceratida, Baculites, and Heteroceras. But their blossom only lasted until the end of Mesozoic. After that, they were all extinct. Mesozoic was also the golden age of marine life such as clams, fish, and sharks. Amphibians and the ancestors of modern frogs existed and developed between land and water. Simultaneously with them, the first birds appeared - perhaps the most famous to science first bird is Archaeopteryx. Later two more species appeared: Ichthyornis and Hesperornis.
It is noteworthy that at this time the first mammals, small animals, many of them not exceeding the size of a mouse also appear. Throughout the Mesozoic, they remained small and by the end of the era, the original births were mostly extinct.
(Interesting fact! - First mammals and birds appeared exactly during the Mesozoic era)
The Mesozoic era is associated with a large number of natural resources deposits. These are sulfur, phosphorites, poly metals, building, and combustible materials, oil, and natural gas.
In Asia, due to active volcanic processes, a Pacific belt was formed, which gave the world large deposits of gold, lead, zinc, tin, arsenic, and other rare metals. In terms of coal reserves, the Mesozoic era is considerably inferior to the Paleozoic era, but even during this period, several large deposits of brown and hard coal were formed - the Kansk basin, the Bureinskoye, and Lena basins.
The Mesozoic oil and gas deposits are located in the Urals, Siberia, Yakutia, and the Sahara.
Why is the Mesozoic Era important?
Although living organisms actively developing in this epoch died out as a result of the global cataclysm, still, the Mesozoic era left a trace in the history of life on Earth, as well as a legacy for subsequent evolution. The Mesozoic exodus proved itself in the following:
- Firstly, in Mesozoic, the vast continents of Gondwana and Laurasia began to split into separate landmasses. By the end of the Mesozoic, the formed continents had shapes similar to those of today.
- Secondly, there were two major changes in vegetation during this era. In the Triassic, the ancient flora was replaced by the domination of saline and advanced fern. In the Cretaceous period, flowering plants appeared, which by the end of this period became practically dominant on Earth.
- And finally, thirdly, by the end of the Cretaceous period, the climate had changed, climate zones had appeared, there was a significant cooling and it was no longer uniformly arid throughout the Earth.
What comes after the Mesozoic Era?
Powerful tectonic processes of alpine folding, which raised new mountain ranges and changed the shape of the continents, fundamentally changed geographic and climatic conditions. Nearly all Mesozoic groups The animal and plant kingdoms are retreating, dying out, disappearing; on the ruins of the old world, a new world emerges, the Cenozoic era, in which life gets a new boost to development and, eventually, living organisms are forming which will later evolve into the ones that live in present days. There are many theories of the death of giant reptiles, the most popular of which is the fall of a giant meteorite. There are others, such as natural processes that have changed the Earth's climate, the degeneration of outdated species, and others. But anyway, the ancient giants have died out for one reason or another. They were replaced by the new life of the newborn Cenozoic.