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Mesozoic Era

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The Mesozoic Era might well be called the ‘Age of the Dinosaurs’ because this is when they existed and ruled the earth.  250 million years ago to 65 million years ago

A General Outline

The Mesozoic started 251.4 million years ago (although I found one source to say 245 million years ago), right after the Paleozoic Era and lasted more than 180 million years.  It started with the Permian-Triassic extinction, also called the ‘Great Dying’, since more than 98% of ocean species and 70% of land vertebrate species were killed.

It took about 30 million yearsfor the Earth to recover from this extinction.  Because of this extinction, it was quite easy for the new species to take over since there was not much competition; that is exaclty what the dinosaurs did.  By the end of the Cretaceous, dinosaurs were the most common species on land.

Three Periods

The Mesozoic is divided into three periods:  Triassic, Jurassic, and Cretaceous.  Each period has different features.   During this Era, in general, the climate was warmer than before, and moister, although the Triassic period is well known for being dry with lots of deserts.  The supercontinent of Pangea (in existence in the Permian) began to break up in the Triassic period.  It was fully broken up by the Cretaceous period, and the longer coastline allowed for a moister climate, with oceans distributed more evenly across the Earth.


The Triassic was generally dry,  with lots of deserts, particularly in the interior of Pangea. The interior of Pangea was far from the oceans which could help keep temperatures from changing much. This the interior tended to have large changes in temperature from very hot to very cold, with very strong seasons. In the Jurassic, with the breaking up of Pangea, deserts began to retreat (get smaller) and extreme temperatures stabilized.

The ocean levels began to rise with the formation of new crust. This, and the fact that much land was now closer to water, things became wetter and warmer.   Then in the Cretaceous, the Earth continued to warm up, and also the temepratures all over the Earth were almost the same, so the equator and the poles were the same temperature (the reason is a bit complex).


The most famous animals are of course, the reptiles.  There were dinosaurs, but there were also the flying reptiles – the pterosaurs; and the sea reptiles –  the plesiosaurs, ichthyosaurs, and mosasaurs.  There were mammals, too but they were small and insignificant compared to the dinosaurs.  Birds, of course, appeared near the end of the Jurassic period.

Then again there wer turtles and crocodiles as well in the mesozoic Era and some of them were very large indeed. Near the end of the Cretaceous period, snakes also evolved.


Ginkos first appeared in this Era (about 150 million years ago), and the gingko biloba still survies today.  Cycads and ferns were also very common.  There were gymnosperms (think of evergreen trees like pine trees as examples), and by the Cretaceous period, angiosperms – flowering plants – had evolved and were abundant (there were no flowers at the start of the Mesozoic Era).

Continental Drift

The Mesozoic Era is also famous for the break-up of the supercontinent Pangea, into the northern continent Laurasia, and the southern continent Gondwana.

See a video about how the continents moved during the Mesozoic Era:

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