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Ancient Meat-Eating Fungus Found Trapped in Amber

James Owen
for National Geographic News
December 13, 2007
 
An ancient flesh-eating fungus that preyed on tiny animals has been found preserved inside a hundred-million-year-old lump of amber, scientists report.

This unlikely fossil predator from the dinosaur era may represent the oldest known carnivorous fungus, according to German researchers.

The amber, from a quarry in southwestern France, also contained worms called nematodes, which the fungus snared in sticky loops before devouring them, according to a team led by Alexander Schmidt of the Berlin Museum of Natural History.

Modern-day carnivorous fungi are known to use constricting rings, adhesive knobs, and similar projections to catch prey, but scientists are unsure when such devices evolved.

The new find suggests these micropredators had already developed complex trapping devices by the early Cretaceous period, which began 145 million years ago, the team reports in the latest issue of the journal Science.

The fungus was found in a single piece of amber kept at the National Museum of Natural History in Paris, France.

Amber, a fossilized tree resin, often preserved prehistoric plant material and creatures that were caught up in the oozy substance before it hardened. (See related photo: "Ancient Tree Frog Found Encased in Amber" [February 17, 2007].)

The study specimen harbored various bugs and other organisms that indicated the resin had solidified in soil, where carnivorous fungi live.

Trapping Rings

The fossil fungus has branched projections called hyphae that are equipped with small rings.

These rings are coated with tiny particles that suggested they produced a sticky secretion used to trap several nematodes that were preserved close to them, the study team said.

The diameter of the microscopic worms matched that of the fungus' rings, the team also noted.

"Because their maximum diameter falls within the width range of the rings, these animals can be identified as potential prey of the fungus," the authors wrote.

"Once trapped, the nematodes were probably penetrated and digested by infestation hyphae," they added. While the rings resemble those found in modern trapping fungi, "the fossils cannot be assigned to any recent carnivorous fungus."

This suggests different groups thrived in the age of the dinosaurs, the researchers said, "and that trapping devices were developed independently multiple times in the course of Earth history."

Nematode-eating fungi expert Philip Jacobs, based in Germany, described the study as "a really amazing report."

Bud Growths

Jacobs noted that the fossil fungus also shows evidence of buds known as blastospores, which are not seen in modern nematode-preying species.

And while none of the nematodes are seen actually inside the trapping rings, "it seems very probable that [the rings] were indeed capturing organs," Jacobs said.

However, George L. Barron, of the Department of Environmental Biology at the University of Guelph, Canada, is more skeptical of the amber findings.

"The presence of nematodes could be coincidental and nothing to do with predation," Barron said in an email.

"Nematodes are commonly found mixed up within organic debris with nonpredatory fungal hyphae."

Barron said the rings of the fungus "are nicely shaped, and it is very tempting to suggest their function as primitive trapping devices," but he added that such features represent "a giant step on the evolutionary scale."

"Someday someone might find the definitive proof in amber, showing a nematode captured in a ring, or a nematode by itself with a ring encircling its body," he added.

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