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Mesozoic era (245 to 65 ma)

The main events that occurred in the Mesozoic were:

  • At the time of the Mesozoic Era, the climate was extremely arid, but as the fragmentation of Pangea occurred, it changed to a humid tropical climate. There was a warm climate, without glaciations in this Era.
  • Due to the rise in sea level, a large part of the continents were flooded, depositing limestone and creating oil deposits .
  • Today's oceans and continents arose in the Mesozoic.
  • In the Mesozoic, dinosaurs and other reptiles appeared, which were the dominant ones of the Age.
  • Birds and mammals emerged.
  • Angiosperm plants appeared.
  • The impact of a meteorite caused a great extinction in the Cretaceous.
Evolución de los continentes en el Mesozoico
P-97 En el proceso de su evolución, cuando los vertebrados poblaron el ambiente terrestre .... - Banco de Preguntas de Biología. (s. f.). Recuperado 25 de abril de 2016, a partir de

The Mesozoic Era is divided into:

Triassic Period (245-208 my)

In the Triassic, Pangea begins to fragment into the continents that we know today.

Different groups of animals appeared, such as dinosaurs (230 my), ammonoids (225 my) and Pterosaurs (205 my).

At the end of the Triassic there was extinction of some living beings.

Paisaje del Triásico
By Ghedoghedo (Own work) [CC BY-SA 4.0], via Wikimedia Commons

Jurassic period (208 to 146 ma)

  • The fracturing and separation of continents that originates the Atlantic Ocean begins.
  • The separation of Antarctica and Australia from Africa occurs.
  • Appearance of the first bony fishmammals and birds.
  • The first animals with a placenta appear.


By Gerhard Boeggemann (File was sent by Gerhard Boeggemann. Gallery) [CC BY-SA 2.5], via Wikimedia Commons

Life in the Mesozoic

Among the most characteristic fossils of the Mesozoic, the ammonites and belemnitesmarine cephalopod mollusks, stand out.

In the Mesozoic, dinosaurs and other great reptiles appeared, which will dominate the Earth during this Era, both seas and continents.

Birds and mammals emerged.

Angiosperms appeared, flowering plants.

Asteroceras BW
De Nobu Tamura ( - Trabajo propio, CC BY 3.0,

Ammonites, marine cephalopod mollusk with external spiral shell, internally divided into chambers.

Belemnoidea fossil characters

By Antonov - Own work, Public Domain,

Belemnites, marine cephalopod mollusk with elongated and solid internal shell.


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.