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RTD info logoMagazine on European Research Special Issue - April 2005   
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PALEONTOLOGY
Title  When life almost died out

Leaden skies. A sun unable to penetrate the thick clouds of dust. Darkness at noon, suffocating air and life that seems to have vanished. A few rare survivors, such as molluscs and mushrooms, are all that inhabit a desolate planet. This is not a nightmare scenario for a possible future, but a description of the Earth 251 million years ago, at the end of the Permian age.

Teaching fossil preservation techniques and an example of extracting a fossil from rock. Scientists with the Palaeontology Research Group are very active in instructing school pupils, as well as their own students. Committed to bringing science and research work to the attention of a broad public, they were actively involved in co-producing the famous BBC series Walking with Dinosaurs.
Teaching fossil preservation techniques and an example of extracting a fossil from rock. Scientists with the Paleontology Research Group are very active in instructing school pupils, as well as their own students. Committed to bringing science and research work to the attention of a broad public, they were actively involved in co-producing the famous BBC series Walking with Dinosaurs .
Although exercising less of a grip on the popular imagination than the extinction of the dinosaurs 65 million years ago, the biological extinction at the end of the Permian age was the most serious our planet has ever experienced. “It is estimated that between 80% and 90% of marine and terrestrial organisms were wiped out,” notes Michael J Benton, a professor of paleontology at Bristol University (UK). “Over the past decade or so, new discoveries in the field and important progress in dating techniques have given us a more precise picture of this period.”

Geopolitics also has something to do with this improved knowledge as some of the best fields of study lie in southern China, an area only recently accessible to international teams. Geological strata revealing details of this wipe-out allowed it to be dated precisely at 251 million years ago. That places it at the junction between the Permian and Triassic periods.

“The disaster was followed by a long period during which the diversity and abundance of species was very limited. It was 100 million years before the biodiversity recovered to anything like the previous level.” (1)

From the bowels of the Earth
The suddenness and the scale of the event first suggested a collision with an asteroid or other meteor. Recent paleontological data suggest a different culprit. The end of the Permian age was one of major volcanic activity that shook the only continent existing at the time, Pangaea. Huge eruptions occurred in what is now Siberia, spitting out 2 million km3 of basaltic lava onto the Earth’s surface that spread across an area equivalent to the size of Europe to a depth of between 400 and 3 000 metres. The dating of this lava, known as the Siberian Traps, coincides perfectly with the Permo-Triassic crisis and suggests that these eruptions were spread over 600 000 years. “Volcanism, and the colossal CO2 emissions that accompany it, are today seen by many scientists as the element that triggered the array of factors at the origin of this brutal crisis.” 

Drawing lessons
Fossils also bear the mark of environmental and climatic change. Before the disaster, life was very diversified and ecosystems complex – some terrestrial reptiles, such as the Gorgonopsians, showed many characteristics associated with mammals. As we move forward, the rare survivors have organisms that make few demands on their environment and are usually small in size. The climate at this time is believed to have shown a temperature rise of 6°C. "It seems that the climate control mechanisms were thrown out of sync by something or other, triggering an effect that added further to the original disaster.”

Some scientists speak of the release of vast quantities of methane, but the subject remains controversial. The contribution of geology and paleontology to the study of the mass extinctions of the past is helping fuel the debate on global warming, as well as benefiting the study and modelling of its effects. 

Map of Pangaea 250 million years ago, based on studies by Christopher Scotese of the University of Texas (USA). This megacontinent remained stable for about 50 million years, until the end of the Triassic period when it began to break up. © Scotese, C.R., 2000,  <a href=http://www.scotese.com  (PALEOMAP website) " src="images/pangee_3200.jpg" width="400" border="0" name="img_3200" />


Map of Pangaea 250 million years ago, based on studies by Christopher Scotese of the University of Texas (USA). This megacontinent remained stable for about 50 million years, until the end of the Triassic period when it began to break up.

© Scotese, C.R., 2000, http://www.scotese.com  (PALEOMAP website)


(1) All quotes are by Michael Benton.


Printable version

Features 1 2 3 4
  The disaster detective
  The ebb and flow of life
  The key to the future lies in the past
  When life almost died out

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  Pangaea and the Permian age

The Permian age (which takes its name from the Russian town of Perm, in the Ural Mountains) started sometime between 295 and 280 million years ago, and ended between 251 and 235 million years ago. This geological period marked the end of the primary era, the Palaeozoic age. At that time, the entire ...
 

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  • Palaeontology Research Group, University of Bristol
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  • Michael J Benton , Palaeontology Research Group, University of Bristol
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    Features 1 2 3 4
      Pangaea and the Permian age

    The Permian age (which takes its name from the Russian town of Perm, in the Ural Mountains) started sometime between 295 and 280 million years ago, and ended between 251 and 235 million years ago. This geological period marked the end of the primary era, the Palaeozoic age. At that time, the entire of the Earth, except for southeast Asia, was covered by a single continent, known as Pangaea, and surrounded by a single ocean, the Panthalassa. Life forms were diverse and included plants, large amphibians and reptiles, including the ancestors of the dinosaurs, molluscs, echinoderms and brachiopods.

    TO FIND OUT MORE

    CONTACTS