Insect Exoskeleton Entombed in Ancient Amber

A crafty insect ditched its shell 50 million years ago, just in time to avoid being caught for eternity in tree sap.

Photo: A small insect akin to a modern-day walking stick had the good sense to stop nibbling on a mushroom and shed its skin before it was covered in sap. Credit: George Poinar, Jr. Oregon State University About 50 million years ago, a smart insect knew it was time to get out of Dodge – or, its exoskeleton – before it was covered with tree sap and became forever trapped in amber.

The rare happy ending to a "stuck-in-amber" story has been documented in the journal Fungal Biology by Oregon State University researcher George Poinar, Jr.

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Poinar found the exoskeleton of an insect similar to today's walking stick in a chunk of Baltic amber, along with a mammalian hair and the mushroom the insect had likely been nibbling on.

The researcher surmises that the story went something like this: A small mushroom became dislodged from a tree, likely gnawed off by a rodent, and both rodent and walking stick began dining on it, just before tree sap flowed over their meal. The ooze snared the exoskeleton and a hair from the small mammal.

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Indeed, it seems to have been a close call for the walking stick.

"It appears to have immediately jumped out of its skin and escaped, just as tree sap flowed over the remaining exoskeleton and a hair left behind by the fleeing rodent," said Poinar in a statement.

The insect would have shed its skin several times during its months-long life, Poinar said. "In this case, the ability to quickly get out of its skin, along with being smart enough to see a problem coming, saved its life."

Poinar knows it was a narrow escape -- that the exoskeleton was "fresh" -- because of the presence of filaments in the exoskeleton that would have disappeared, had the sap covered the exoskeleton long after its former owner left the scene.

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Both the insect and the mushroom species are long extinct. The insect was a phasmid species, according to Poinar, a group whose members use their shapes to camouflage themselves as sticks or leaves.

The mushroom, meanwhile, is of a new genus and species and is the first mushroom to be found in Baltic amber, Poinar notes.

The tiny drama came courtesy of the famous Baltic amber deposits of Northern Europe, which formed from fossilized resin that oozed from coniferous trees in forests that stretched over the area tens of millions of years ago.

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