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The Weekend Image --A 100-Million Year Old Spider Attack

 

 

          Spider_in_amber_fossil-e1349882942848

This extraordinarily rare fossil is in a piece of amber that preserved a spellbinding event in remarkable detail. This spider inhabited the Hukawng Valley of Myanmar in the Early Cretaceous –almost certainly with dinosaurs wandering nearby. Researchers have found what they say is the only fossil ever discovered of a spider attack on prey caught in its web – a 100 million-year-old snapshot of an engagement frozen in time in a piece of amber that preserved this event in terrifying detail. Its large eyes now stare for eternity at its attacker, moving in for the kill.

Aside from showing the first and only fossil evidence of a spider attacking prey in its web, the piece of amber also contains the body of a male spider in the same web. This provides the oldest evidence of social behavior in spiders, which still exists in some species but is fairly rare. Most spiders have solitary, often cannibalistic lives, and males will not hesitate to attack immature species in the same web.

“This juvenile spider was going to make a meal out of a tiny parasitic wasp, but never quite got to it,” said George Poinar, Jr., a professor emeritus of zoology at Oregon State University and 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.”

Spiders are ancient invertebrates that researchers believe date back some 200 million years, but the oldest fossil evidence ever found of a spider web is only about 130 million years old. An actual attack such as this between a spider and its prey caught in the web has never before been documented as a fossil, the researchers said.

The tree resin that forms amber is renowned for its ability to flow over insects, small plants and other life forms, preserving them in near perfection before it later turns into a semi-precious stone. It often gives scientists a look into the biology of the distant past. This spider, which may have been waiting patiently for hours to capture some prey, was smothered in resin just a split second before its attack.

This type of wasp, Poinar said, belongs to a group that is known today to parasitize spider and insect eggs. In that context, the attack by the spider, an orb-weaver, might be considered payback.*Both the spider and the wasp belong to extinct genera and are described in the paper. At least 15 unbroken strands of spider silk run through the amber piece, and on some of these the wasp was ensnared.

The Daily Galaxy via Oregon State University 

Comments

I wonder what the size of these things are compared to todays comparable insects? have insects changed much in size over the last 100 million years?

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