The 230 million-year-old gall mites were named Triasacarus fedelei (top) and Ampezzoa triassica (bottom). (Photo : University of Göttingen/A. Schmidt)
They may be small and sometimes even invisible to the eye, but arthropods make up almost 90 percent of all the species in the animal kingdom. Now, three amber-preserved arthropods have been found dating back 230 million years ago - almost 100 million years older than the previous oldest arthropod specimens found.
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The specimens found included two plant-eating mites, Triasacarus fedelei and Ampezzoa triassica, and one fly that could not be readily identified because its body parts were not well preserved.
Amber is essentially fossilized resin that is a useful medium to study fossils through.
"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," said co-author of the paper David Grimaldi, a curator in the American Museum of Natural History's Division of Invertebrate Zoology.
Arthropods have been known to have existed as early as 400 million years ago, but the oldest fossils found until now were only 130 million years ago. One of the surprising things about the recent discovery has to do with the fact that the mites were remarkably similar to their makeup today.
"You would think that by going back to the Triassic you'd find a transitional form of gall mite, but no," Grimaldi said. "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."
The Triassic period, which goes from about 250 million to 200 million years ago is an important evolutionary milestone for creatures on Earth. The Triassic began and ended with mass extinctions, and dinosaurs first appeared around 230 million years ago, around the same time as these fossils are dated to.
Sadly, those looking for a glimpse into early dinosaur DNA through the mites will be disappointed. The plant-eating mites had no taste for dinosaur blood.