TITLE: Extinction: How Life on Earth Nearly Ended 250 Million Years Ago
AUTHOR: Douglas H. Erwin
DATE PUBLISHED: 2015 Updated Edition - New Preface (first publication 2006)
"Some 250 million years ago, the earth suffered the greatest biological crisis in its history. Around 95 percent of all living species died out--a global catastrophe far greater than the dinosaurs' demise 185 million years later. How this happened remains a mystery. But there are many competing theories. Some blame huge volcanic eruptions that covered an area as large as the continental United States; others argue for sudden changes in ocean levels and chemistry, including burps of methane gas; and still others cite the impact of an extraterrestrial object, similar to what caused the dinosaurs' extinction.
Extinction is a paleontological mystery story. Here, the world's foremost authority on the subject provides a fascinating overview of the evidence for and against a whole host of hypotheses concerning this cataclysmic event that unfolded at the end of the Permian.
After setting the scene, Erwin introduces the suite of possible perpetrators and the types of evidence paleontologists seek. He then unveils the actual evidence--moving from China, where much of the best evidence is found; to a look at extinction in the oceans; to the extraordinary fossil animals of the Karoo Desert of South Africa. Erwin reviews the evidence for each of the hypotheses before presenting his own view of what happened.
Although full recovery took tens of millions of years, this most massive of mass extinctions was a powerful creative force, setting the stage for the development of the world as we know it today.
In a new preface, Douglas Erwin assesses developments in the field since the book's initial publication."
Erwin provides us with an entertaining, informative and somewhat technical "whodunit" detective story, examining the "culprits" that may be responsible for the end-Permian mass extinction. The author examines the various geological and paleontological evidence for what happened, when and what effects this may have had; and then tries to piece together which of several hypotheses are the more likely culprites of the extinction and which are just effects.
The six major hypotheses that show some supporting data, and which Erwin focuses on, are as follows:
(1) an extraterrestrial impact of the some sort;
(2) extensive volcanism that produced the Siberian flood basalts (possibly triggered by an extraterrestrial impact), that radically changed the global climate and geochemistry;
(3) continental drift (plate tectonics) with the formation of Pangaea that caused an extensive reduction in biome types;
(4) extensive glaciation that caused a combination of global cooling and a drop in sea levels;
(5) a decrease in oxygen in shallow and deep seas due to one of several possible causes; and
(6) the "Murder on the Orient Express" hypothesis suggesting that a combination of several or all of the other already described events occurred nearly simultaneously
Erwin very helpfully comments on the strenght or weaknesses of the various hypotheses, and finally provides his conclusion based on the evidence. Erwin also takes a look at the recovery of organisms AFTER the extinction, which is something few authors do. However, the book was originally published in 2006, so some of this information is outdated or been superseededby additional information. Erwin does discuss the new findings in his 2015 preface, for an up-to-date examination of the end Pemian extinction. Despite new research into this topic, it seems like the author's "Murder on the Orient Express" hypotheses, where a variety of factors are responsible for the mass extinction, still seems to be valid.
Other useful books:
-When Life Nearly Died: The Greatest Mass Extinction of All Time by Michael J. Benton
-The Worst of Times: How Life on Earth Survived Eighty Million Years of Extinctions by Paul B. Wignall
-Life on a Young Planet: The First Three Billion Years of Evolution on Earth by Andrew H. Knoll
-The Goldilocks Planet: The Four Billion Year Story of Earth's Climate by Jan Zalasiewicz and Mark Williams
-The Ends of the World: Supervolcanoes, Lethal Oceans, and the Search for Past Apocalypses by Peter Brannen
-The Emerald Planet: How Plants Changed Earth's History by David Beerling