Paleozoic life
From Palaeos
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Paleozoic topics: Stratigraphy | Geography | Climate | Life | References | Links |
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When the Paleozoic era began (Cambrian explosion) the seas were dominated by invertebrates. That dominance continued in the Ordovician period too, with the mollusks. In the Silurian, the bony-fishes were larger than early vertebrates (Haikouichthys), but were still jawless.
With the end of the Silurian period the first plants had evolved (cooksonia) and the first jawed fishes had also evolved. The fishes dominated the seas in the Devonian period and the plants evolved to trees and the first tetrapods evolved from sarcopterygian fishes. The Devonian period ends with the extinction of many groups of fishes (placoderms etc.).
Later, in the Carboniferous period the trees evolved into swamp forests and the first amniotes appeared (reptiles). As result of that, the oxygen which reached into air cause the evolution of large arthropod predators (Meganeura, Megarachne, etc.), but apart from this the full-oxygen air also caused strong storms. After the vast swamp forests the climate was drying and the arthropods had extinct. However, the reptiles could survive and the first medium to large-sized reptiles evolved. The Permian period world was dominated by reptiles.
The continents were fusing together (Pangaea) and the world was covered by dry land - deserts. Later a group of reptiles appeared called 'mammal-like reptiles' and that group survived the great Permo-Triassic extinction and evolved later to mammals. The Paleozoic era ends with the greatest mass extinction of many groups of animals.
