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The prominent of Earth ’s mass extinctions may have give animals gasping for air , a new field of study finds .
The Great Dying , as it is called , occurred some 250 million days ago . rough 90 percent of all maritime life die , as well as nearly three - quarters of all land works and animal . It marks the transition from the Permian geologic stop to the Triassic .
A depiction of present-day Earth overlaid with simulated atmospheric oxygen of the early Triassic period. Because oxygen was low even at sea level, animals would have been restricted to very low altitudes, green or light-shaded areas. Red or dark-shaded areas are higher elevations where many animals could not have found sufficient oxygen and so could not have lived or even traversed, leaving lowland populations fragmented and isolated.
While fossils reveal the extinction in concrete terms , its causes are less well known . scientist have blamed the monumental dice - off onan asteroid , volcanoes , global thaw , and any compounding thereof .
Now Raymond Huey and Peter Ward of the University of Washington have shown that a reduced supply of oxygen could excuse high quenching rates that preceded the Great Dying , as well as the very obtuse recovery that stick to .
Currently , O makes up about 21 percent of our atmosphere , but in the early Permian period it was 30 percent . From this invigorating storey , it fell to about 16 percent at the time of the Great Dying and over the next 10 million long time continued to drop to 12 pct .
" Oxygen knock off from its highest level to its lowest level ever in only 20 million years , " Huey said today .
With oxygen only 16 percent of the atmosphere , animals at sea level breathed air similar to that at the top of a 9,200 - infantry muckle today . At 12 percent , the corresponding elevation would be 17,400 invertebrate foot . If you ’ve ever climb such a mountain , you hump the core .
" Animals that once were able-bodied to spoil mountain make it quite easily suddenly had their bm severely restrict , " Huey said .
This negate theprevailing viewof Pangea , the superintendent - continent that exist back then and which later broke apart to form all the modern Continent . Most paleontologists considered it a " state highway " on which specie could drift freely , Ward said . But with so little atomic number 8 , high elevations would behave as barriers .
secret populations would be more vulnerable to other environmental challenges , like severe climate change . It would also take longer for isolated being to bounce back .
The finding were release in the April 8 edition of the journalScience .
Pangaea
Pangea began to break up about 225 - 200 million year ago . This animation shows how it unfolded .
generator : USGS
