100-million-year-old amber tomb traps ancient mushroom

A Kentucky nurse has found the oldest known mushroom, entombed in a 100-million-year-old piece of amber from Burma.

A closer examination of the mushroom cap measuring less than a tenth of an inch revealed it had been infected by an ancient parasite, which a second parasite was feeding on.

"I was amazed enough with the mushroom," said George Poinar, a retired entomology professor in Corvallis, Ore. "But then seeing the parasites was astonishing. No one has ever seen this three-tier association before."

Poinar, formerly of the University of California, Berkeley, said the mushroom was detected about a year ago by Ron Buckley, a registered nurse and amber-fossil collector and photographer from Florence, Ky. Buckley sent the amber specimen to Poinar, who confirmed the discovery and found the two parasites.

"This shows how far back mushrooms — and the parasites that infect them — go," Poinar said. "They dotted the trees 100 million years ago, so they probably were tasty treats for the dinosaurs to nibble on."

Poinar and Buckley reported their discovery in the journal Mycological Research.

Amber is fossilized tree resin, a sticky substance that oozes from certain pine and legume trees. The resin has chemical properties that act as a natural embalming agent.

"I knew right away what it was when I looked at it under the microscope," said Buckley, who has been collecting amber fossils for the past eight years.

The mushroom is about 20 million years older than previously found mushroom fossils. The amber apparently broke off the mushroom's stem.

Joseph Spatafora, a fungi specialist and a professor of botany and plant pathology at Oregon State, said the amber discovery is significant because mushroom fossils are rare.

Few ancient mushrooms survive because they lack bones or shells that help preserve other organisms.