Ignored for Decades, Insect Fossil Is Declared World's Oldest

New York Times ^ | February 11, 2004 | CAROL KAESUK YOON

[68skylark]

Scientists say they have discovered the world's oldest known insect fossil — a 400 million-year-old set of minuscule jaws that lay unrecognized for nearly a century in a lonely drawer at the Natural History Museum in London.

The findings, being published on Thursday in the journal Nature, pushes the date for the appearance of insects, one of the most successful life forms on earth, some 10 million to 20 million years back in the fossil record. And they suggest that insects were among the first animals to live on land.

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The authors also argue that these ancient insects flew. If true, that would mean that flight — one of life's most important and vigorously investigated evolutionary innovations — evolved much earlier than suspected, 70 million years before the oldest fossilized insect wing. Scientists say the finding puts insects, already recognized as the earliest animal fliers, up in the air a good 170 million years before anything else, even flying dinosaurs.

"We were at the museum to look at another famous insect fossil, one that everyone's been discussing for the past 80 years," said Dr. David Grimaldi, a curator of entomology at the American Museum of Natural History, who co-wrote the paper with Dr. Michael S. Engel, a paleoentomologist at the University of Kansas. But the two could not resist examining the other, curious fragment stored in the same drawer, a curious bit of fossil that had long ago been dismissed as being of little interest. Dr. Grimaldi said, "We looked at each other and said, `Holy Moley!' "

Dr. William Shear, a paleobiologist at Hampden-Sydney College in Virginia, who is a discoverer of what had been considered the oldest insect fossils, said of the new claim: "It's a very convincing case. These guys were smart enough to come and along and re-analyze these things and they took a look and they got the goods."

Perhaps other scientists can be forgiven for having missed the significance of this fossil, dubbed Rhyniognatha early in the last century. Its jaws measure less than one-two-hundred-fiftieth of an inch across. Embedded in a partly translucent crystalline rock, known as chert, from Rhynie, Scotland, such fossils can only be clearly seen when the chert is cut with diamond saws, polished and then examined under a powerful microscope.

Under bright lights and high magnification, the jaw fragments exhibit several telltale features — including sockets that form part of a hingelike mechanism — that clearly identify them as the mouth parts of a true insect. But this oldest known insect fossil is not, a member of the most primitive lineage of insects. Instead, the authors say, based on the stoutness and other subtler features of these jaws, which look like the tips of two tiny bird wings, Rhyniognatha is part a lineage of more advanced insects.

"So that means that everything that diversified prior to that must have been older than that fossil," said Dr. Engel. If so, it would push the origin of insects back into the dim shadows of the Silurian period, more than 400 million years ago, when plants were just edging up onto land, followed by the first animals. He added, "So they were among the earliest of terrestrial faunas."

Because the jaws appear to place the fossil species among lineages of insects that exhibit well-developed wings, the authors expressed confidence that little Rhyniognatha could indeed fly. But Dr. Shear called that conclusion "a bit shakier," saying that it could be possible for such jaws to evolve without flight. While the results were very suggestive of flight, he said, the study lacks "a smoking gun, or smoking wing."

So until Rhyniognatha's tiny body is found in the Scottish chert or other ancient fliers are uncovered, scientists will probably continue to debate the date of the origin of animal flight. Researchers expressed hope that the new finding would get paleontologists digging into this crucial chapter in the history of life. Even now a Scottish team of scientists has begun excavating the Rhynie chert for new fossil flora and fauna.

"There are jackpots out there waiting to be grabbed hold of," Dr. Engel said.

[BradyLS]

Can't we talk about the probability of life existing on Mars (if water once flowed there) instead? I mean, we now have reasonably strong evidence pointing to the distinct possibillity of flowing water in Mars' past!

[BradyLS]

How much memory, in Gigabytes, does a 1 Trilobyte harddrive hold?