In an engagement frozen in time, the extraordinarily rare fossils of the spider and its prey, a wasp, are entombed in a piece of amber, Oregon State University reported Monday.
"This juvenile spider was going to make a meal out of a tiny parasitic wasp, but never quite got to it," said OSU zoology Professor George Poinar Jr., a world expert on insects trapped in amber.
"This was a male wasp that suddenly found itself trapped in a spider web," Poinar said. "This was the wasp's worst nightmare, and it never ended. The wasp was watching the spider just as it was about to be attacked, when tree resin flowed over and captured both of them."
An actual attack by a spider on its prey caught in a web has never before been documented as a fossil, the researchers said.
Both the spider and the wasp belong to species that are now extinct, they said.