Volcanic Gas Made the World fit for Dinosaurs
Russel Jackson
Scotsman, UK
___________
The mystery of how dinosaurs came to be may have been solved.
According to scientists, the creatures evolved after a giant cloud of poisonous volcanic gas wiped out their early ancestors.
The research reveals vital clues about the mass extinction of animals at the end of the Permian period, 250 million years ago, when mammal-like reptiles known as synapsids roamed the planet.
Many scientists thought that an asteroid hitting the Earth or a deep-sea methane release had caused the extinction, which obliterated more than two-thirds of reptile and amphibian families. However, analysis of a unique set of molecules found in rocks taken from the Italian Dolomites has enabled scientists to build up a picture of what actually happened.
The molecules are the remains of polysaccharides, large sugar-based structures common in plants and soil, and they tell the story of the extinction. The molecules date from the same time as a major volcanic eruption that caused the greatest ever outpouring of basalt lava over vast swathes of land in present-day Siberia.
Reporting their findings in the science journal Geology, the researchers say volcanic gases from the eruption, which would have depleted Earth's protective ozone layer and acidified the land and sea, killed rooted vegetation.
This meant that soil was no longer retained and it washed into the surrounding oceans. The chemistry of the rocks reveals that although the sugar molecules were found in marine sediments, they derived from land, supporting the theory of massive soil erosion. Soil materials in the oceans would have blocked out light and soaked up oxygen.
Dr Mark Sephton, from Imperial College London's Department of Earth Sciences and Engineering and lead author of the research, said the extinction of the synapids actually helped dinosaurs to evolve.
Dec 02, 2005
Russel Jackson
Scotsman, UK
___________
The mystery of how dinosaurs came to be may have been solved.
According to scientists, the creatures evolved after a giant cloud of poisonous volcanic gas wiped out their early ancestors.
The research reveals vital clues about the mass extinction of animals at the end of the Permian period, 250 million years ago, when mammal-like reptiles known as synapsids roamed the planet.
Many scientists thought that an asteroid hitting the Earth or a deep-sea methane release had caused the extinction, which obliterated more than two-thirds of reptile and amphibian families. However, analysis of a unique set of molecules found in rocks taken from the Italian Dolomites has enabled scientists to build up a picture of what actually happened.
The molecules are the remains of polysaccharides, large sugar-based structures common in plants and soil, and they tell the story of the extinction. The molecules date from the same time as a major volcanic eruption that caused the greatest ever outpouring of basalt lava over vast swathes of land in present-day Siberia.
Reporting their findings in the science journal Geology, the researchers say volcanic gases from the eruption, which would have depleted Earth's protective ozone layer and acidified the land and sea, killed rooted vegetation.
This meant that soil was no longer retained and it washed into the surrounding oceans. The chemistry of the rocks reveals that although the sugar molecules were found in marine sediments, they derived from land, supporting the theory of massive soil erosion. Soil materials in the oceans would have blocked out light and soaked up oxygen.
Dr Mark Sephton, from Imperial College London's Department of Earth Sciences and Engineering and lead author of the research, said the extinction of the synapids actually helped dinosaurs to evolve.
Dec 02, 2005
