Earth history is divided into chunks of time, most importantly aeons, eras and periods. Dinosaurs and other prehistoric reptiles were the dominant animals for about 185 million years during the Mesozoic era, which was a section of the Phanerozoic aeon. More simply, the Mesozoic era lasted from 250 million years ago to 65 million years ago, and contained three periods called the Triassic, Jurassic and Cretaceous.
The first reptiles appeared during the Palaeozoic Era (570 million to 245 million years ago), just before theMesozoic Era (245 million to 65 million years ago).
Each of these eras is divided up into sections called periods.
The Palaeozaic era
1. Cambrian period: (570 million years ago) - The first fishes, corals, trilobites and shellfish appeared.
2. Ordovician period: (505 million years ago) - The first nautiloids appeared. Corals and trilobites were common.
3. Silurian period: (438 million years ago) - The first land plants and giant sea scorpions called Eurypteridsappeared.
4. Devonian period: (408 million years ago) - The first amphibians, insects and spiders appeared.
5.Carboniforous period: (360 million years ago) - The first reptiles appeared. Great swamp forests covered the land.
6. Permian period: (286 million years ago) - The first sailback reptiles such asDimetrodon(right) appeared.
the Mesozaic era - the beginning of the dinosaurs...
1. Triassic period: 245 million years ago - The first dinosaurs such as Coelophosis and Euskelosaurus, and mammals, turtles, crocodiles and frogs appeared.
2. Jurassic period: (208 million years ago) - The first birds appeared (e.g. Archaeopteryx).
Dinosaurs included diplodocus, stegasaurus, brachiosaurus.
3. Cretaceous period: (144 million years ago) - Dinosaurs during this time included muttaburrasaurus, quetsalcoatlus, ankylosaurus. The dinosaurs died out towards the end of this period.The first snakes and modern mammals appeared.
All through this time the earth was changing.
In the Triassic period, all the continents were joined together in one huge landmass. Climate was hot and dry but with rain seasons. The first tree ferns and coniferous trees were starting to appear.
In the Jurassic period the climate changed as the huge continent was breaking up. There were now forests of cycads, conifers and gingko, all plants that still exist today.
In the Cretaceous period the continents had separated and each had its own flora and fauna. However, Australia and Antarctica were still joined together. There were now flowering plants such as magnolias and waterlilies.
In the Triassic period, all the continents were joined together in one huge landmass. Climate was hot and dry but with rain seasons. The first tree ferns and coniferous trees were starting to appear.
In the Jurassic period the climate changed as the huge continent was breaking up. There were now forests of cycads, conifers and gingko, all plants that still exist today.
In the Cretaceous period the continents had separated and each had its own flora and fauna. However, Australia and Antarctica were still joined together. There were now flowering plants such as magnolias and waterlilies.
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