Dinosaurs were very likely roaming nearby when tree resin flowed over a spider attacking a wasp in its web and created a rare fossil 100 million years ago.
The spider attack was frozen in time – preserved in a piece of amber – and found in the Hukawng Valley in Myanmar.
"This juvenile spider was going to make a meal out of a tiny parasite wasp, but never quite got to it," said George Poinar, Jr., a professor emeritus of zoology at Oregon State University. "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."
The amber also captured the body of a male spider in the same web, as well as 15 unbroken strands of spider silk that ensnared the wasp.
It's the only fossil of its kind ever discovered, and Poinar says it's the oldest evidence of spiders' social behavior.
Poinar is a world expert on insects trapped in amber, and he just published the findings in the journal Historical Biology.
Tree resin that forms amber is a common source of fossils of insects and small plants. The resin in the fossil above smothered the spider a split second before its attack. Both the spider and the wasp species captured are now extinct.