The Paleozoic Era

  • The Paleozoic Era, one of the longest of the Eras, is the oldest Era which started approximately 541 million years ago and ended about 252 million years ago.
  • Its name means “ancient life” in Greek and it is known for the variety of life that rapidly began to appear.
  • The Paleozoic Era can be subdivided into six geologic periods.
  • These include: the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and the Permian Periods.

The Cambrian Period:

  • The Cambrian Period is a Geologic Time Scale period which ran from 541 million years ago to 485 million years ago.
  • During this time, an event called the Cambrian Explosion began which resulted in an unprecedented number of creatures evolving during one single period in Earth’s entire history.
  • Some of the flora which evolved during this time included algae and some of the animals that evolved included creatures such as trilobites.
  • It was also during this time that most of the world’s major marine phyla started evolving.

The Ordovician Period:

  • Running from approximately 485 to 440 million years ago, the Ordovician Period was a period of time in which many of the animal species that we are familiar with today starting evolving.
  • Some of these species include cephalopods, snails, shellfish and primitive fish.
  • This was also a period of time in which corals started evolving.
  • On the cusp of the Ordovician and Silurian Periods, there was a major extinction event which resulted in approximately 60% of the marine invertebrates to become extinct.
  • This is considered to be the First Mass Extinction.

The Silurian Period:

  • Spanning from approximately 440 to 419 million years ago, the Silurian was a Geologic Time Scale period in which the Earth was beginning to recover from the First Major Extinction.
  • It was a time when Snowball Earth began to warm and the number of marine animals began to dramatically rise.
  • During this period, jaw-less fish multiplied, jawed fish began to first evolve and it is also the time when freshwater fish began to evolve.

The Devonian Period:

  • Starting around 419 million years ago and ending about 360 million years ago, the Devonian Period was known for an uptick in the number of fish and the diversification of these fish.
  • This resulted in many paleontologists referring to this period as the Age of the Fish.
  • However, fish wasn’t the only animals to evolve.
  • This was also a time when amphibians began to evolve.
  • It was also a time when flora such as trees began to evolve.
  • 4 million years before the end of this period, the Second Mass Extinction hit the world.
  • This extinction wiped out 57% of all marine genera.

The Carboniferous Period:

  • Starting approximately 360 million years ago and ending about 300 million years ago, the Carboniferous Period is a place in Earth’s timeline in which the average global temperatures of the world began to rise.
  • Average worldwide temperatures were approximately 68 degrees Fahrenheit (about 20 degrees Celsius).
  • The landscape of the Earth during this geological time scale was mainly tropical swamps.
  • As these tropical trees began to die after their natural lifespans were over, they would eventually become peat which would then, in turn, eventually become rich deposits of coal over time.

The Permian Period:

  • The Permian Period originated around 300 million years ago and ended about 250 million years ago.
  • This period on the Geologic Time Scale was the last period of the Paleozoic Era.
  • During this period, the Earth was at its driest as compared to any other previous period and it was also a period of time which was dominated by synapsids and reptiles.
  • Conifers also began to evolve and would eventually come to dominate the dry terrain.
  • At the end of this period was the Third Mass Extinction known by many paleontologists as the “Great Dying.”
  • All but 5% of the world’s life would go extinct during this period.