Life on the Earth was pushed to the edge of extinction at least five times. The worst happened about 250 million years ago (mya) when 90 percent of life was wiped out. However, our Deep Ancestors survived the Great Dying of the Permian Period to repopulate the Earth. We, the Living today, are the result of their endurance, and ability to change.
Our Deep Ancestors are more than simply interesting animals. They may seem far removed from us, but we carry Them inside of ourselves, as a part of our DNA. We would do well to listen and gain wisdom from Them especially on how to adapt to the changing times.
Tracing Ancestors: The tracing of human ancestry, from prehistory to the present, is not a linear process. At present, the fossil records are incomplete to accomplish this. Instead, paleontologists will zigzag from known fossils to known fossils, and guess at the gaps in-between.
Mass Extinction: A mass extinction event occurs when there is a sharp decrease in the diversity and abundance of life on earth. This usually happens when undue stress is placed on living things because of a changing environment. The “official zoological definition” is the decrease of two to five taxa such as Classes or Orders. Generally, this means that at least ten percent of all families, forty percent of all genera (genus), and seventy percent of all species die out at one time.
Major Mass Extinction Events: There were five major extinction events in the earth’s history. The most severe was the Permian-Triassic Event (258 mya). Known as “The Great Dying”, 57 percent of all families, 83 percent of all general, and at least 90 percent of all species died out. In addition, this extinction event ended the primacy of mammal-like reptiles and ushered in the Age of Dinosaurs.
The second worst extinction event was the Ordovician-Silurian Event (443 mya), when 27 percent of all families and 57 percent of all genera died out. The only mass extinction of insects occurred at this time. After this event came the diversification of land species and new ecosystems.
The other extinction events were the Late Devonian Event (19 percent families, 50 percent genera, and 70 percent species, 354 mya) when the trilobites disappeared. The Triassic-Jurassic Event (23 percent families and 48 percent genera, 206 mya) saw the end of large amphibians and many mammal-like reptiles. The well-known Cretaceous-Paleogene (Tertiary) Event (17 percent families, 50 percent genera, and 75 percent species, 65 mya) wiped out the dinosaurs and gave rise to the Age of Mammals.
Haines, Tim and Paul Chambers, “The Complete Guide to Prehistoric Life”, Firefly: Ontario, 2006.
Pianka, Eric and Laurie Vitt, “Lizards: Windows to the Evolution of Diversity”, University of California, Berkeley, 2003.
Turner, Alan, “National Geographic Prehistoric Mammals”, National Geographic Society, Washington D.C., 2004.
Various, “Prehistoric Life”, Dorling Kindersley, New York, 2009.