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MESOZOIC ERA


MESOZOIC ERA

This is subdivided into three periods viz:
         
Cretaceous            (about 144  -  66.4  mya) - The youngest period in the Mesozoic era

         
          Jurassic                 (about 208  -  144  mya)

Triassic                 (about 245  -  208  mya) – The oldest period in the Mesozoic era


ACTIVITIES IN THE TRIASSIC PERIOD
Appearance of Primitive Mammals
Emergence of the Continents

Terrestrial deposition starts

Marine Invertebrates reduced in population (mass extinction)

Archosaurs occured on land as dinosaurs, Pterosaurs in the air while Ichthyosaurs, Nothosaurs  in  oceans

Formation of red beds

Global climate and ocean circulation was altered

Formation of Gypsum and Salt

Climate was arid

Lizards, modern conifers, first turtles, dinosaurs, cycadeoids, and mammals appeared

Appearance of first mammals and crocodiles

Orogenic activities still continued in some parts

Ceratitic ammonoids were in abundance

Pangaea was still in existence (intact)



ACTIVITIES IN THE JURASSIC PERIOD
Pangaea broke up into Gondwanaland and Laurasia

Dinosaurs that eat green plants existed

Gymnosperms abounded

Palm-like cycads and Ferns abounded

There was a hyper increase in the Atmospheric CO2

First frogs appeared, also flying reptiles, birds, salamanders, crocodiles, were present

Sponges, starfish, crinoids were abundant   


Various types of Dinosaurs were in dominant

Sea  urchins  were  ubiquitous



THE CRETACEOUS PERIOD

ACTIVITIES IN THE CRETACEOUS PERIOD
Belemnites, Marine Pelecypods, sponges and bivalves were common

Appearance of first primates

Chalk deposits were present

New types of insects evolved

Flying reptiles and toothed birds (Primitive birds) were present

Angiosperms were present

Formation of Rocky Mountains

Various types of dinosaurs were on the land

Various types of crocodiles were on the land

Modern flowering plants were present new types of insects.

Gondwanaland broke up

Echinoids, Ammonites were all over


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