Top Story: August 30, 2012

Ancient Arthropods in Amber

ambermites

You can teach an old mite new tricks! Check this out!

Searching through 70,000 teeny pieces of amber from the Italian Dolomite Alps, researchers discovered a treasure. Well, three treasures actually: two mites and a fly, fossilized 230 million years ago!

These ancient insects represent the oldest arthropods in amber ever discovered—by about 100 million years. While limestone and shale may hold older arthropod finds, amber is, well, kind of like a diamond in the rough. (Academy geologist Jean DeMouthe would kill me if she read that sentence.).

“Amber is an extremely valuable tool for paleontologists because it preserves specimens with microscopic fidelity, allowing uniquely accurate estimates of the amount of evolutionary change over millions of years,” says study co-author David Grimaldi of the American Museum of Natural History.

While the fly is difficult to identify because only its antennae were intact, the mites are described as a new species in a group called Eriophyoidea. This group has about 3,500 living species that sometimes form abnormal growth called “galls.”

The ancient gall mites are surprisingly similar to ones seen today, says Grimaldi. “Even 230 million years ago, all of the distinguishing features of this family were there—a long, segmented body; only two pairs of legs instead of the usual four found in mites; unique feather claws, and mouthparts."

But unlike present-day gall mites that feed on flowering plants, these ancient mites subsisted on conifer-related trees.

“We now know that gall mites are very adaptable,” Grimaldi says. “When flowering plants entered the scene, these mites shifted their feeding habits, and today, only 3 percent of the species live on conifers. This shows how gall mites tracked plants in time and evolved with their hosts.”

The findings are published in the current edition of the Proceedings of the National Academy of Sciences.

Image: University of Göttingen/A. Schmidt

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