US: 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.
David Grimaldi of the American Museum of Natural History in New York and Michael Engel of the University of Kansas were doing research for a book on the evolution of insects when they spotted the remains while examining the fossil.
"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 in an interview yesterday. "It's remarkable that no one took the time to carefully study the fossil and then compare it to some modern insects."
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, who reported the findings in the science journal Nature.
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.
"This is a tantalising piece of evidence that suggests we have a considerable window of time in which we are missing the fossils," said Grimaldi.
The insect's body would have been about the size of a grain of rice. Because they are so small, fossils of insect wings are difficult to find.