Paleozoic Era – Concept, animals and stages

We explain what the Peleozoic era is and what this historical period consisted of. In addition, the stages that constitute it and its animals.

Paleozoic era
The Peleozoic era lasted more than 290 million years.

What is the Paleozoic era?

It is known as Paleozoic era, Primary era or simply Paleozoic, to a period of the geologic timescale, that is, the scale with which the history of the world is measured, inscribed together with the Mesozoic and Cenozoic in the Phanerozoic Aeon (from 542 million years ago to the present).

The term Paleozoic means “old life” (from the Greek palaio, “Old”, and zoe, “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 it was an extremely rich period from a biological point of view, transition between the kingdom of invertebrate animals and that of vertebrates or higher. During this time the seas were literally filled with life and migrated to land, conquering new habitats and expanding 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

Peleozoic era
The Cambrian period is characterized by its large amount of marine life.

The Paleozoic era is classified into a set of six periods, which are:

  • Cambrian or Cambrian (541 ma ago – 485 ma 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 bacteria. Fifty phyla of living beings have their origin in this period, initiating biomineralization (appearance of shells and shells).
  • Ordovician (485 million years ago – 444 years ago). Life was contained in the seas, since the absence of abundant atmospheric oxygen made life on land impossible. However, the diversification of living beings in the sea was exponential, and towards the end of the period the first plants and fungi emerged 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 million years ago – 416 years ago). 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 spiny sharks, 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 sea water levels.
  • Devonian (416 million years ago – 359 years ago). In this period bony fish and large coral reefs appear, trilobites and ammonites predominate, forms of Paleozoic life now extinct, but popular. Plants with seeds spread through the land and finally the first amphibians appear, as well as the first terrestrial arthropods. Towards the end of the period another major extinction occurred, primarily affecting marine life.
  • Carboniferous (359 my ago – 299 my ago). 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 forests and plant life. Amphibians invade the earth 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 million years ago – 251 years 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.