Scientists have discovered the remains of a 400 million-year-old insect, the oldest ever located, in a fossil unearthed in Scotland in the early 1900s.

Dr David Grimaldi, of the American Museum of Natural History in New York, and Associate Professor Michael Engel, of the University of Kansas, published details of their find in today's issue of the journal Nature.

The U.S. scientists spotted the remains of the flightless bug in a fossil while researching a book on insect evolution.

"We're the first to have re-studied it in any detail that I am aware of and the first to have definitively come up with evidence and an interpretation about the significance of it," Grimaldi said.

"It's remarkable that no one took the time to carefully study the fossil and then compare it to some modern insects."

The scientists looked at the creature's mandible and concluded that its structure definitely made it an insect.

They dated Rhyniognatha hirsti at 408 to 438 million years old.

The discovery pushes back the earliest known insect by 20 million years, but even more importantly it suggests that winged insects evolved some 80 million years earlier than previously thought.

"Insects would have been among the earliest land animals," said Grimaldi.

One of the biggest questions in evolution is why, how and when wings in insects evolved. The earliest evidence of insect wings is from about 330 million years ago. Specimens from that era show they were fully formed and capable of manoeuvred and powered flight so they probably evolved earlier.

"It [the finding] makes the search for early insect wings even more intense," said Grimaldi.

"This is a tantalising piece of evidence that suggests we have a considerable window of time in which we are missing the fossils."

The remains of the early insect consist of a pair of mandibles, or jaw parts, and other features that indicate it is a true insect and a structure that suggests it belonged to a group of insects that had wings.

Its body would have been about the size of a grain of rice. Because it was so small, fossils of wings are difficult to find.

"Recent fossils that are 10, 20 or 30 million years old are quite well preserved but the farther you go back the more there is going to be destruction, particularly of small things like insects," Grimaldi said.

The specimen was found in old red sandstone in Rhynie, Scotland and now resides at the Natural History Museum, London.

The source of the given news and copyrights belong to the ABC Online News

Back