The Earth has experienced a number of mass extinctions throughout its history. During the Permian age, land mass exceeded oceanic area for the first time. Many new species inhabited the Earth during this time, from insects to reptiles on land, to bony fish and sharks in the ocean. However, large numbers of these species were wiped out during the extinction that occurred at the end of this period, to an extent that the Earth nearly lost its ability to support life.
Time Frame
The Permian age lasted from 290 to 248 million years ago. The Permian era was the last of the Paleozoic period that saw an explosion of species that populated the oceans and the lands that had emerged from the water. The broken land masses of the drifted and crashed into each other, creating a single, large land mass called Pangea. This land mass allowed species to move freely across the Earth, evolving and adapting to different environments. This movement allowed species to diversify greatly during this period. At the time of the Permian extinction up to 90 percent of all marine life forms and 70 percent of land animals on Earth were destroyed.
Causes
The factors involved in mass extinctions are complex, and few experts agree on the specific causes. However, several factors are likely to be in play. The formation of glaciers on the southern land mass known as Gondwana could have caused massive changes in water levels, as it did during the Ordovician and Devonian periods. Some experts believe that volcanic eruptions that emitted large ash clouds full of sulfates could have changed the environment enough to cause mass extinctions on the Earth. The formation of land masses and changes in the continental shelves beneath the water could also have played a part in the extinction, but this is not certain.
Species Affected
The environmental crisis during the Permian age is thought to be the closest that the planet ever came to losing all its life forms. The great variety of species that developed during the Permian period. Corals were among the hardest hit species during the Permian extinction. Sea sponges and many shelled creatures were devastated. Trilobites vanished for good. On the land, many reptiles, amphibians and insects were wiped out. The plant families lost many species, though they were more resilient than animal species.
Re-speciation of the Earth
Even the widespread devastation of land and marine creatures was not enough to stop the revitalization of the Earth. New forms adapted to the changed environmental conditions. These species were then able to diversify even further to create the planet we know today with its innumerable life forms.
Though mass extinctions occurred many times, the Earth has been able to recover its life forms through the process of evolution and natural selection. The essence of our planet’s nature seems to be this ability to fall and yet always recover, regardless of the massive changes it must endure.
