Mesozoic Era – Definition, Facts, Timeline, Plants, Animals, And How It Ended

Mesozoic Era Facts
Source: ND Geological Survey

The Mesozoic Era was a collection of three geological time periods when life on earth – especially in the Animal Kingdom and the Plant Kingdom – saw a drastic change, wherein more powerful, efficient, and complex animals such as dinosaurs (who once ruled the world), birds, and reptiles who could swim, walk, and fly evolved.

A collection of Triassic, Jurassic, and Cretaceous geological time periods, the Mesozoic Era was a huge era of diversified life forms, interesting extinction cases, and a pivotal moment for evolution. The era was home to various species that marked the gap between older and primitive animals and modern complex animals, thus being the “middle animals”. In this article, we will talk about everything related to the Mesozoic Era- Mesozoic era facts, definition, timeline, plants, animals and even how the Mesozoic era came to an end. So keep reading. 

Mesozoic Era Definition

The meaning of the word “Mesozoic” can be better understood by splitting it. “Meso” means “middle” or “intermediate” and “zoic” is a word used in relation to animals. Therefore, “Mesozoic” means “middle animals” or “intermediate animals.” Further, the word “era” means a long and distinct time period in history. Hence, “Mesozoic Era” stands for an extended period in history wherein intermediate animal species were ubiquitous. Pretty simple!

Mesozoic Era Timeline

You must be thinking about how long did the Mesozoic Era last. Set in an extended time period from 250 million years ago to 60 million years ago, the approximately 190 million years of the Mesozoic Era largely encompasses three different time periods. The first is Triassic (250 to 200 million years ago), followed by Jurassic (200 to 145 million years ago), and finally the Cretaceous (145 to 60 million years ago). These time periods are also called Geologic Periods.

Triassic Geological Period

The Triassic Geological Period, which started after the Permian-Triassic extinction event – known as the “Great Dying” as in this time period, approximately 96% marine species and 70% vertebrates became extinct or severely endangered. The loss of species was so severe, it led to the evolution of more than a hundred thousand entirely new and different species in each kingdom. These new species mark the beginning of the Triassic Geological Period.

Jurassic Geological Period

Perhaps your favorite, the Jurassic period is famously known for the prominent presence and dominance of dinosaurs, who are claimed to have “ruled the earth” during the Jurassic Era like humans do today. Although dinosaurs started evolving in the Triassic Geologic Period, the Jurassic saw many more and efficient species of dinosaurs which were the strongest species that existed at their time. In fact, dinosaurs got so diversified that many of them could swim and/or fly. The tragic end of the Jurassic Geological Period, however, is famously marked by “The Great Extinction” though scientists are not sure what exactly caused this extinction. It is believed that there was excessive plant decay, though there has been no solid proof to date.

Cretaceous Geological Period

The final time period of the Mesozoic Era, the Cretaceous Geological Period is the longest time period ranging for over 80 million years. During this period, the huge landmasses (known as continents today) had significantly separated farther away from each other. Due to this expansion of seaways, the Cretaceous period led to the extinction of almost all dinosaur species (such as sauropods). However, it also led to the evolution of various new species of dinosaurs that could switch between closely located islands. The Cretaceous Geological Period also led to the formation of various new marine species, including multiple species of flying fish. It was a period of warm climate, which gave rise to the universal symbol of beauty – flowers. It is known that flowering plants started evolving during the Cretaceous period. Note that the dinosaurs still pretty much ruled the earth during the Cretaceous Geological Period. The end of the Cretaceous period (along with the Mesozoic Era itself) was marked by what it is known as “Cretaceous-Tertiary extinction”. This is when an asteroid struck harshly on the earth’s surface, resulting in destroying three-fourths of entire species of any kind on earth, including most of the dinosaurs too.

Mesozoic Era Animals

Mesozoic Era is home to the organisms which evolved from primitive animals and led to the formation of modern complex animals. Due to their key role in the transition between primitive to complex animals, they are often called “middle animals.” They are also referred to as “Beta animals”, which is a computer science term referring to anything that is being tested, thus indicating that the animals in the Mesozoic Era were god’s “test” which led to the formation of modern complex animals.

The mass extinction of almost all species at the beginning of the Triassic Geological Period allowed for the formation of many new species and groups of species. During the Triassic Period, various interesting species such as cynodonts and dicynodonts appeared. Dinosaurs also started to evolve during the Triassic era and took full charge by the time Jurassic Era started. The first birds and eutherian mammals (mammals similar to rats) started appearing in the Jurassic period too. During most of the Mesozoic Era, animal life was dominated by archosaurs, dinosaurs, and Pterosaurs (flying reptiles). Indeed, reptiles saw their towering period in the Mesozoic Era which gradually decreased after the Mesozoic era when mammals showed higher signs of strength and intelligence.

Although biodiversity at the beginning of the Mesozoic era was minimal, by the mid-Triassic Period, the biodiversity actually grew larger than ever before, the food web became extremely complex, and the evolution of animals started becoming even more specialized.

Mesozoic Era Plants

However, it was not only the animals that had evolved during the Mesozoic Era. It is a long established fact that there is no existence of animals without plants, due to the balanced gas exchange cycle that the two kingdoms have. Therefore, when animal species go through severe change, it is often found that plant species themselves have a huge impact on the same.

Thus, due to the extreme diversification or animal species, the plant species saw extremely large speciation during the Mesozoic Era. Land plant species were dominated by vascular, non-flowering, cone-framed plants called gymnosperms. A prominent example is conifers (which are present today as well) that did not produce bare seeds (which do not have any coating) though they have evolved so that today they do have coated seeds. Moreover, flowers – the undebated universal symbol of beauty and peace – first formed in late the Mesozoic Era. Imagine a world without flowers! So sad dinosaurs didn’t have a chance to see them.

Fun Fact: Grass – which today is considered nothing but normal and omnipresent since the beginning of earth – first became widespread during the Cretaceous period and rarely existed before that.

Mesozoic Era Tectonics

At the beginning of the Mesozoic Era, the landmasses were in the form of a huge mother mainland, called the Pangaea. It was in the Jurassic geological period that Pangaea starting splitting into separate landmasses, also known as continents. Initially, Pangaea broke up into two large lands known as Laurasia and Gondwana, at which time the Atlantic Ocean started to develop. Laurasia then split into the landmasses of North America and Eurasia. Gondwana turned into South America, Africa, Australia, Antarctica, and the Indian subcontinent. The Indian Continent, after the Mesozoic Era, slammed into Eurasia shaping a chain of tremendously tall mountains known as the Himalayas. In fact, this slam was so harsh that it formed the tallest mountain on the planet: the famous Mount Everest. Furthermore, since the Indian tectonic plate is different from the Asian plate, the collision point between the two plates often leads to earthquakes near the northern Indian and southern China region.

Mesozoic Era
Source: ND Geological Survey

Mesozoic Era Environment

The environmental temperature was surprisingly warm during the Mesozoic Era. Moreover, icy places and polar ice tops did not yet exist or were in a limited mass during the Mesozoic Era. This had an extensive impact in advancement and is a key factor behind the prospering and dominance of the dinosaurs, who went on to rule the world during the Mesozoic Era.

In the Triassic time frame, the atmosphere was usually dry, which then changed close to the Jurassic time frame as seas ascended due to the mounting of layers of magma that covered the ocean bed. Thus, flooding overwhelmed numerous parts of the uncovered land in the motherland continent – Pangaea.

This resulting in the atmosphere changing with the expansion of moistness and it proceeded with that level of moistness even into the Cretaceous geological time period. Contrastingly though, the atmosphere started to become cooler in the Cretaceous geological period while there was no particular reason for a Cretaceous time period to have weather much different than the other time periods during the Mesozoic Era. Scientists are still searching on what led to this drop in temperature, while currently, they claim that the temperature reduced because the main motherland – Pangaea – which started splitting into 7 broad continents also distributed the gross heat, resulting in an overall drop of temperature.

How Did The Mesozoic Era End?

The end of the Mesozoic Era is a famous tale, but perhaps one of the most dangerous and harsh extinctions of the five major extinctions on the planet. This is the same story as the end of the dinosaurs which you well must have heard. At the end of the Mesozoic Era, more than 60 million years ago from today, the Cretaceous-Paleogene extinction event took place, also known as the “Cretaceous-Tertiary (K-T) extinction.” This was a sudden mass extinction that led to the end of more than three-fourths of all the world’s species. There existed more than a hundred thousand species of tetrapod species. However, after the attack except for a few lucky species such as turtles and crocodiles, no tetrapod species survived the massive attack. Such was the impact and extent of extinction which resulted at the end of the Mesozoic Era.

Scientists believe that the sudden extinction took place because an asteroid – no less than 10 to 15 kilometers in diameter – crashed on the surface of our planet. The crater of this asteroid is known as the Chicxulub Crater, which is 112 miles wide. It is present in the Gulf of Mexico. It was found in the 1990s, which means the crater has been on earth for more than 190 million years.

This very asteroid led to the extinction of almost all dinosaur species, any other type of species, ended the Cretaceous Geological Period, the Mesozoic Era itself, and started the Cenozoic Era (which is still going on).

Mesozoic Era Facts

  1. The Mesozoic era was filled with crazy things like dinosaurs and single landmass and asteroid collisions. Now that you have got some background information about the Mesozoic Era, it’s time for some fun facts!
  2. The Mesozoic Era lasted for more than 190 million years.
  3. The Mesozoic Era ended when a huge asteroid crashed on earth.
  4. Dinosaurs ruled the world during the Mesozoic Era.
  5. The first flowers started forming in the Mesozoic Era.
  6. Birds evolved during the Mesozoic Era.
  7. In the starting and during the middle Mesozoic Era, there was only one continent – the Pangaea.
  8. By the end of the Mesozoic Era, the Pangaea split into 7 different landmasses, which exist as the 7 continents today.
  9. Mesozoic Era is known for its warm and desert-like environment.
  10. The sea levels during the Mesozoic Era were the lowest in world history.
  11. At the beginning of the Mesozoic Era, nearly all life forms were extinct. Likewise, by the end of the Mesozoic era, the mass extinction killed nearly 98% of all species.

Clearly, the Mesozoic Era was a large Geological Era spanning over 190 million years inclusive of three geological time periods, which encompassed so many interesting events and things such as the presence and obvious dominance of dinosaurs, the splitting of a single landmass into today’s seven continents, the start and evolution of various bird and flower species, and a phenomenal end with the collision of an asteroid. Now, certainly, this Era sounds too entertaining.

Alrighty young nerds, hope you enjoyed reading this article on Mesozoic Era. Nerdy Caterpillar makes sure you get information on the highest and nerdiest quality. Stay tuned with us to receive more informative and nerdy articles!


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