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Post Info TOPIC: Insects


L

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RE: Insects
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Researchers at the U.S. Department of Energy's Argonne National Laboratory have cast new light on why the giant insects that lived millions of years ago disappeared.
In the late Palaeozoic Era, with atmospheric oxygen levels reaching record highs, some insects evolved into giants. When oxygen levels returned to lower levels, the insect giants went extinct.


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L

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For the giant insects that roamed Earth 300 million years ago, there was something special in the air.
A higher concentration of oxygen in the atmosphere let dragonflies sometimes grow to the size of hawks, and some millipede-like bugs reached some two meters in length, a new study suggests.
Now that the proportion of oxygen has decreased, however, bugs can't grow much larger than they do now, the authors write.
The reason: The bigger an insect, the bigger the proportion of its body devoted to its tracheal system, which functions like a lung but is far less efficient at large sizes.

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L

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Higher concentrations of oxygen could produce giant insects according to a paper presented at the Comparative Physiology conference currently meeting in Virginia Beach, Virginia.
The paper, "No giants today: tracheal oxygen supply to the legs limits beetle size," based on research by a team of American researchers, offers evidence that Palaeozoic insects were substantially larger because they had a richer oxygen supply. During the late Palaeozoic period, about 300 million years ago, the air's oxygen content was around 35 percent, compared to 21 percent today. As a result some dragonflies had two-and-a-half-foot wing spans, while giant spiders roamed the ancient forests.

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