This is the VOA Special English SCIENCE REPORT.
American scientists have reported finding the largest complete remains of a cockroach ever discovered. The scientists say the insect was about the size of a small animal. They say it lived three-hundred-million years ago. That is fifty-five million years before the first dinosaurs appeared on Earth.
Scientists say the fossil discovery could lead to a better understanding of ancient creatures. They say it also could help show how Earth's climate has changed over the years.
Cockroaches are among the oldest creatures on Earth. Some scientists believe cockroaches may have been on Earth for as many as four-hundred-million years.
Cockroaches also are among the most common creatures on Earth. Scientists know about almost four-thousand different kinds of cockroach. Only a small number of the insects are considered harmful to humans.
Scientists found the cockroach fossil two years ago in a coal mine in the state of Ohio. It was found with the remains of hundreds of other plants and animals. Scientists say the ancient insect lived during a period on Earth when the area was hot and wet. They say extremely dry weather was beginning to dry out the wetlands.
Cary Easterday is a graduate student at Ohio State University in Columbus. He was among the scientists who found the fossil. He said that scientists normally only hope to find fossils of shell and bones. That is because shell and bones have minerals that increase their chances of being protected. He said something unusual about the chemistry of the ancient area protected creatures without shells or bones.
The ancient cockroach was nine centimeters long. It was preserved in great detail. The remains of the insect's legs, mouth parts and wings are easy to see. Mr. Easterday presented his findings at a meeting of the Geological Society of America. The group met earlier this month in Boston, Massachusetts.
Mr. Easterday compared the fossil to modern cockroaches. The ancient insect was about two times as big as the average American cockroach. However, some cockroaches that live in warmer climates are even larger. They grow to a length of thirteen centimeters. The smallest known cockroaches are only a little more than one centimeter long.
This VOA Special English SCIENCE REPORT was written by George Grow.