We explain what the Peleozoic era is and what this historical period consisted of. In addition, the stages that constitute it and its animals.
What is the Paleozoic era?
It is known as the Paleozoic era, Primary era or simply Paleozoic, a period of the geological time scale, that is, the scale with which the history of the world, inscribed together with the Mesozoic and Cenozoic in the Phanerozoic Aeon (from 542 million years ago to the present).
The term Paleozoic means "ancient life" (from the Greekpalaio, "Old", andzoe, "Life"), name that was assigned to this period because it is in which the oldest known forms of life proliferate: beings with shells or exoskeletons.
The beginning of this temporary stage, which lasted more than 290 million years, is located 542 million years ago with the dissolution of the supercontinent Pannotia and culminates 251 million years ago, with the beginning of the Mesozoic and the formation of the supercontinent.Pangea.
The Paleozoic era was an extremely rich period from a biological point of view, transition between the kingdom of the Invertebrate animals and that of the vertebrates or higher. During this time the seas were literally filled with life and migrated to earth, conquering new habitats and spreading all over the planet.
Climatically, this period was characterized by the increase in the warmth of the planet, which led to an average stability that coincides with the proliferation of oxygen in the atmosphere. This occurred after the Upper Ordovician ice age, a cold wave that caused one of the two great mass extinctions of the Phanerozoic Aeon.
Stages of the Paleozoic era
The Paleozoic era is classified into a set of six periods, which are:
- Cambrian or Cambrian (541 m.a. ago - 485 m.a. ago). This period is characterized by the "great explosion" of life, which crowded the seas and gave way, for the first time in the history of the planet, to multicellular living beings, much more complex than protists and the bacteria. Fifty phyla of living beings have their origin in this period, initiating biomineralization (appearance of shells and shells).
- Ordovician (485 mi ago - 444 mi ago). Life was contained in the seas, since the absence of abundant atmospheric oxygen made life on land impossible. However, the diversification of living creatures at sea was exponential, and towards the end of the period the first plants Y mushrooms out of the water. There was also an ice age in almost all regions of the globe, causing a massive Ordovician-Silurian extinction, only surpassed by the later Permian-Triassic extinction.
- Silurian (444 BC - 416 BC). After extinction, life on land continues to be vegetal and restricted to marsh environments, but in the sea there is a repopulation of complex animals such as cartilaginous fish and sharks thorny, which dominated the warm and abundant waters along the equator. At the end of the Silurian, another mass extinction event occurred, although much smaller than the previous one, known as the Lau event, due to the decrease in the levels of the Water from sea.
- Devonian (416 m.a. ago - 359 m.a. ago). In this period bony fish and large coral reefs appear, trilobites and ammonites predominate, forms of Paleozoic life now extinct, but popular. The seedlings spread through the earth and the first appear at last. amphibians, as well as the first terrestrial arthropods. Towards the end of the period another major extinction occurred, primarily affecting marine life.
- Carboniferous (359 BC - 299 BC). Its name comes from the fact of the formation of most of the mineral coal mined in our time, product of the burial of huge contingents of woods and plant life. Amphibians invade the land and give rise to the first reptiles. The insects were abundant and of enormous size, given the abundance of ambient oxygen, which reached levels of 35% of the atmosphere. This period was very volcanically active and witnessed the rise of Pangea, culminating in a new ice age.
- Permian (299 m.a. ago - 251 m.a. ago). The last stage of the Paleozoic era, witnessed the appearance of the first mammals, turtles and primitive dinosaurs (lepidosaurs and archosaurs). Climatically the period tended towards drought and aridity, pushing back glaciers and drying up many swamps. Towards the end of the period there was the Permian-Triassic mass extinction, one of the largest on record, in which 90% of marine life and 70% of terrestrial life ended. It is not very well known what this catastrophic event was due to from a biological point of view.