What was early life like? When did the first tree begin to evolve? How did underwater life explode with amazing new creatures? When did first fish evolved ? When did sharks first appear?
Earth History/Life in the Paleozoic Era:
The Paletozoic word is a word derived from the Greek language which meaning “ancient life”. This era is the oldest of the three geologic ages of Phanerozoic Eon. It is the longest of the Phanerozoic eras, which lasted from 541 to 251.9 million years ago, and is divided into six geologic periods. It was a time of dramatic geological, climatic and evolutionary change. The plants became widespread. The Paleozoic era began with the Cambrian explosion and ended with the Permian extinction. During this era, invertebrate animals brought diversity to the oceans. Plants, amphibians and reptiles also migrated to the land.
The story of the oldest Paleozoic animals is the story of life in the sea. Probably simple fungi and related forms existed in freshwater environments, but the fossil record provides no evidence of these modes of life.
The Paleozoic era includes the six periods described here:
Cambrian Period: (541 to 485.3 mya)
The Cambrian marked an increase in an event known as the Cambrian explosion in which the largest number of organisms evolved in any one period of Earth’s history. New types of organisms exploded in the Cambrian period. The explosion involved the development of arthropods (ancestors of today’s insects and crustaceans) and chordates (animals with rudimentary spinal cord). The Cambrian spanned from about 541 to 485.3 million years ago.
Ordovician Period: (485.3 to 444 mya)
During this period, the first fish evolved and plants colonized the land for the first time. This was a time in the history of the Earth in which many biological classes still prevalent today, such as fish, cephalopods, and coral. The most common forms of life, however, were snails, trilobites, and shellfish. The Ordovician spanned from about 485.3 to 444 million years ago.
Silurian Period: (444 to 419.3 mya)
During this Period (444 to 419.3 million years ago) large-scale growth of fish was observed, as jawless fish grew in number, jawed fish evolved, and the first freshwater fish evolved, although marine. Arthropods such as scorpions were still top predators. Vascular plants appeared on the land.
Devonian Period: (419.3 to 359 mya)
The first seed plants developed during this period. The first amphibians also evolved, and fish was now at the top of the food-chain. The Devonian spanned from about 419.3 to 359 million years ago.
Carboniferous Period: (359 to 299 mya)
During this period, the average global temperature was very high. Tropical marshes dominated the Earth. In addition, the first reptiles and synapsid evolved in the swamps. Extensive forests of giant plants left massive deposits of carbon that eventually turned into coal. The most important evolutionary development at the time was the development of the amniotic egg, which allowed the amphibians to move further inland and remain the dominant vertebrates for the duration of this period. The Carboniferous spanned from about 359 to 299 million years ago.
Permian Period: (299 to 252.3 mya)
The last period of the Palaeolithic period spanned from 299 to 252.3 million years ago is known as the Parmen period. All large tracts collided together to form a great continent called Pangea. During this period the temperature was extreme, and the climate was dry. Organisms such as Dimetrodone and Edaphosaurus ruled the new continent. During this time the mass of the land was very dry with harsh weather.The Permian period ended with mass extinction.