Features of the Mesozoic era – The Mesozoic is the geological time interval from about 252 to 65 million years ago. The Mesozoic is also known as the Age of Reptiles. This is because this period was dominated by reptiles such as Iguanodon, Megalosaurus, Plesiosaurs and what is now called Pseudosuchia. The phrase was introduced in the 19th century by paleontologist Gideon Mantell.
Mesozoic meaning “middle life” comes from the Greek prefix meso for “between” and zoon meaning “animal” or “living thing”. The Mesozoic is one of the three geological eras of the Phanerozoic Eon, preceded by the Paleozoic and succeeded by the Cenozoic.
This era is divided into three main periods: Triassic, Jurassic, and Cretaceous, which are further divided into epochs and stages. This era began with the Permian-Triassic extinction event, the largest recorded mass extinction in Earth’s history, and ended with the Cretaceous-Paleogene extinction event.
Another mass extinction known for killing non-avian dinosaurs as well as other plant and animal species. The Mesozoic was a significant period of change in tectonics, climate and evolutionary activity. This era could witness the gradual split of the supercontinent Pangea into separate landmasses which would eventually move to their current positions.
The climate of the Mesozoic was varied, alternating warming and cooling periods. Overall, the Earth is hotter than it is today. Non-avian dinosaurs appeared in the Late Triassic and became the dominant land vertebrates early in the Jurassic Period, and remained in this position for about 135 million years until their extinction at the end of the Cretaceous.
It is known that the Mesozoic era has three designations, namely the age of the reptiles, the medieval age, and the secondary age. The Cretaceous is about 90 million years old, then the Jurassic is 140 years, and the Triassic is about 190 years.
Quoted from Just the Facts : Prehistoric Age by Dougal Dixon, the Triassic Age is the time when the dinosaurs began. Dinosaurs evolved at the end of the Triassic period. The dinosaurs ruled until the end of the Cretaceous. When the continents separated, new dinosaurs evolved on each continent. At the end of the Cretaceous, disasters wiped out the dinosaurs, pterosaurs, and marine reptiles. This catastrophe later became the start of the first mammals.
General characteristics of the Mesozoic Age
The Mesozoic Age has several characteristics, namely:
- The climate is warm and dry due to the growth and development of flora and fauna
- The emergence and development of various types of broadleaf plants, amphibians, fish, reptiles, and the first mammals
- Limited distribution of flora and fauna
- The development of a type of giant reptile
- Lasted from 252 million years ago to 66 million years ago
- Ends with the disappearance of the Dinosaurs
According to the Geography Student Guide , the Mesozoic era had the following characteristics:
- The climate is hot and wet due to the growth and development of flora and fauna
- Began to emerge and develop species of broadleaf plants, the first mammals, amphibians, fish, and reptiles
- Limited distribution of flora and fauna
Characteristics of the Mesozoic Age Based on Life Periods
1. Geological Period
The Mesozoic Era spans about 186 million years, from 252.17 to 66 million years ago when the Cenozoic Era began. The length of time is divided into three geological periods. From oldest to youngest. Triassic Period (252.17 to 201.3 million years ago). Jurassic Period (201.3 to 145 million years ago). Cretaceous Period (145 to 66 million years ago).
The lower (Triassic) boundary is marked by the Permian-Triassic extinction event. Which is about 90% to 96% of marine species and 70% of land vertebrates became extinct. It is also known as the “Great Dying” because it is considered the largest mass extinction in Earth’s history.
The (Cretaceous) upper bound was set at the Cretaceous-Tertiary (KT) extinction event which is now more properly called the Cretaceous-Paleogene extinction event which may have been caused by the impact that formed the Chicxulub Crater on the Yucatán Peninsula.
But the lead up to a major volcanic eruption in the Late Cretaceous Period is also believed to have contributed to the Cretaceous–Paleogene extinction event. About 50% of all genera became extinct, including all non-avian dinosaurs.
2. Triassic Period
The Triassic period occurred around 250 million-200 million years ago. The Triassic Period was an arid and desolate transitional state in earth’s history between the Permian-Triassic Extinction and the lush and fertile Jurassic Period, having three main epochs, namely the Early Triassic, Middle Triassic and Late Triassic. The Early Triassic period lasted between 250 million-247 million years ago and was dominated by deserts because Pangea had not yet been divided, so the interior landmasses were still arid.
Earth just witnessed a major extinction event in which 95% of all life became extinct. The most common life on Earth were Lystrosaurus, Labyrinthodont, and Euparkeria along with many other creatures that managed to survive. Middle Triassic covers 247 million-237 million years ago.
The Middle Triassic is the time when Pangea broke up, and the Tethys Sea. The ecosystem has recovered from the destruction. Phytoplankton, coral, and crustaceans have recovered, and the reptiles are getting bigger and bigger. Aquatic reptiles such as Ichthyosaurus and Nothosaurus were just evolving.
Meanwhile, on land, pine forests thrive, along with mosquitoes and fruit flies. The first ancient crocodiles evolved, which sparked a competition with the large amphibians that have ruled the freshwater world since.
Unfortunately, the Triassic period had to end due to a mass extinction. The mass extinction occurred when the supercontinent Pangea split into Laurasia and Gondwana. Thus, there was an increase in eruption activity and global climate change which led to mass extinctions.
The Late Triassic covers 237 million – 200 million years ago. After the Middle Triassic, the Late Triassic is characterized by frequent heat waves, as well as moderate rainfall (250-500 mm per year). The final warming led to a boom in the evolution of land reptiles and the first true dinosaurs to evolve, as well as pterosaurs.
All of these climatic changes, resulted in the major extinction event known as the Triassic-Jurassic extinction event, in which all archosaurs, most of the synapsids, and almost all amphibians were wiped out, as well as 34% of marine life in the world’s fourth mass extinction event.
3. Jurassic Period
The Jurassic period spanned from 200 million years to 145 million years ago and contained 3 main epochs: the Early Jurassic, Middle Jurassic, and Late Jurassic. Time of the Early Jurassic Period from 200 million to 175 million years ago. The climate is much more humid than the Triassic, so the world is very tropical.
In the oceans, plesiosaurs, ichthyosaurs and ammonites filled the waters as the dominant races of the sea. On land, dinosaurs and other reptiles share their claim as the dominant land race, with species such as Dilophosaurus at the top.
During the early Jurassic period, the supercontinent Pangea broke up into the supercontinents Laurasia and Gondwana. The Gulf of Mexico was opened due to a rift with North America, until now known as the Yucatán Peninsula in Mexico.
The North Atlantic Ocean is relatively narrow, whereas the South Atlantic Ocean did not open until the Cretaceous when Gondwana split. The Tethys Sea closed, and the Neo Tethys Valley appeared. The climate is getting warm and there is evidence of glaciers appearing. As in the Triassic, there appears to have been no land at either pole, and no extensive ice sheets.
Geological records of the Jurassic period in western Europe, in which extensive oceanic sequences indicate a time when most of the future landmass was submerged under shallow tropical seas; notable areas include the Jurassic Coast World Heritage Site in southern England and the famous Jura lagerstätten due to the late discovery of Holzminden and Solnhofen in Germany.
While records of the Jurassic period in North America are very few. Although the epicontinental Sundance Sea left marine deposits on the northern plains of the United States and Canada during the Late Jurassic, the most exposed sediments from this period are the continents themselves.
Several large batholiths in the North American Cordillera beginning in the mid-Jurassic period, mark the Nevadan orogeny. Important discoveries about the Jurassic period were also found in Russia, India, South America, Japan, Australia and England.
In Africa, the Early Jurassic strata are distributed similarly to the Late Triassic strata, with outcrops being more common in the south and less common fossil beds being dominated by a northerly pathway.
As the Jurassic period continued, larger and more iconic dinosaur groups such as the Sauropods and Ornithopods flourished in Africa. Middle Jurassic strata are not well represented or well studied in Africa.
Late Jurassic strata are also underrepresented apart from the spectacular Tendaguru Formation in Tanzania. Late Jurassic life is very similar to that found in western North America’s Morrison Formation.
The first true crocodiles evolved, pushing the large amphibians out to near extinction. Reptiles rise to rule the world. Meanwhile, the first true mammals evolved, but remained relatively small in size. The Middle Jurassic period covers 175,000,000-163,000,000 years ago.
During this epoch, reptiles flourished as large herds of sauropods, such as Brachiosaurus and Diplodocus, filled with the fern grasslands of the Middle Jurassic Period. Many other predators went up too, such as Allosaurus. Coniferous forests comprise most of the forest. In the oceans, plesiosaurs were quite common, and ichthyosaurs were thriving. This age is the pinnacle of reptile life.
The Late Jurassic period took place from 163 million to 145 million years ago. The end of the Jurassic period saw the mass extinction of sauropods and ichthyosaurs as a result of the split of Pangea into Laurasia and Gondwana in an event known as the Jurassic-Cretaceous extinction event. Rising sea levels destroyed the fern meadows and created shallows after them.
Ichthyosaurs became extinct, while sauropods did not die out entirely in the Jurassic Period; in fact, some species, such as Titanosaurus, lived until the KT extinction. Rising sea levels opened up Atlantic sea passages that would continue to widen over time. The divided world will provide an opportunity for new diversification of dinosaurs.
During the Jurassic period, about four or five of the 12 clades of planktonic organisms that exist in the fossil record either underwent major evolution or for the first time. Among the plankton species, foraminifera and coccolithophores are two new groups that are rapidly developing and spreading.
Some experts ascribe diatoms to the Late Jurassic and spread during the Cretaceous. Prior to the mosque dispersal of skeletal planktonic organisms, carbonates were mostly deposited in shallow water such as nearshore environments. During the Jurassic period, many dinosaurs were found, both herbivorous, omnivorous and carnivorous dinosaurs.
4. Cretaceous Period
The Cretaceous period is the longest period in the Mesozoic, but this period only has two epochs, namely the Early Cretaceous and the Late Cretaceous. The Early Cretaceous lasted from 145 million-100 million years ago. The Early Cretaceous saw the expansion of sea lanes, and resulted in the decline and extinction of the sauropods. The Cretaceous period saw many coastal shoals, and that caused the ichthyosaurs to become extinct.
The Cretaceous period, also known as the Cretaceous, is one of the periods on the geological time scale that began at the end of the Jurassic period and took place in the early Paleocene, or around 145.5 ± 4.0 to 65.5 ± 0.3 million years ago, from the small extinction event that closed the Jurassic Period to the extinction event. Cretaceous-Paleogene.
This period is the longest geological period and covers almost half of the Mesozoic era. The end of this period marks the boundary between the Mesozoic and Cenozoic.
The Mosasaurus evolved to replace them as the apex marine predators. Some island-hopping dinosaurs, such as Eustreptospondylus, evolved to live on the coastal shoals and islets of ancient Europe. Other dinosaurs rose to fill the void that the Jurassic-Cretaceous extinction event had created, such as Carcharodontosaurus and Spinosaurus.
The most successful dinosaurs, later became Iguanodon which spread to every continent. The seasons returned and the poles cooled down, but dinosaurs still inhabited the area, such as Leaellynasaura, which inhabited the arctic forests all year round, and many dinosaurs migrated there during the summer, such as Muttaburrasaurus.
Too cold for crocodiles, the area is a last line of defense for large amphibians, such as the Koolasuchus. Pterosaurs got bigger as species like Tapejara and Ornithocheirus developed.
The Late Cretaceous lasted 100 million-65 million years ago. The Late Cretaceous displayed a cooling trend that would continue into the Cenozoic. Finally, the tropics are limited to the equator and areas outside the tropics have extreme seasonal changes.
Dinosaurs are still developing as new species such as Tyrannosaurus, Ankylosaurus, Triceratops and Hadrosaur dominate the food chain. In the seas, mosasaurs ruled the seas, replacing ichthyosaurs, and large plesiosaurs, such as Elasmosaurus, evolved.
At the end of the Cretaceous, Deccan and other volcanic eruptions poisoned the atmosphere. It is thought that a large meteor crashed into Earth, creating the Chicxulub Crater in the event known as the KT Extinction, the fifth and final mass extinction event, in which 75% of life on Earth became extinct, including all non-avian dinosaurs. Everything that was over 10 kilograms went extinct. The age of the dinosaurs is over.
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Author: Yufi Cantika Sukma Divine
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