Roughly 230 million years ago, two mites and a midge got stuck in oozing resin from a now-extinct species of conifer tree in the mountains of northeastern Italy. They never moved again. Despite their ignoble deaths, the insects have now earned the distinction of being the oldest arthropods—invertebrates that include insects, arachnids, and crustaceans—ever found preserved in amber. Arthropods have scuttled and crawled over Earth’s surface for more than 400 million years, but prior to this discovery the oldest specimens collected in amber were only 130 million years old. The three amber-bound arthropods were sorted from roughly 70,000 2 millimeter to 6 millimeter bits of amber (upper left image) excavated from an outcrop in the Italian Dolomite Alps. They date about 100 million years earlier than previously collected specimens, and were probably trapped during a 10-million-year climatic shift that caused the trees to produce more resin than usual, researchers say. Although they could not identify the midge fly due to lack of well-preserved body parts, the mites are intact at a microscopic level of detail, which allowed the team to identify two new species of mites: Triasacarus fedelei (center) and Ampezzoa triassica (right). In their study, published today in the Proceedings of the National Academy of Sciences, the researchers report that the mites are the oldest known ancestors of the Eriophyoidea group of mites. Today, this group includes at least 3500 species and has a distinctive body type including bristly appendages called "featherclaws." Their presence in 230-million-year-old amber, researchers say, shows for the first time that mites evolved long before the appearance of flowering plants.
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