Detail view of three amber drops from the Triassic. Photo: University of Padova / Stefano Castelli
Reading aloud About 230 million years ago, they died in a drop of resin: two gall mites and a two-leaved insect were thus preserved in amber for eternity. They are now the oldest known testimonies of arthropods in amber. The tiny ambassadors of the Triassic Triassic were discovered by an international research team in amber droplets from the Italian Dolomites. They are 100 million years older than all the previously preserved finds of this group of animals, to which all present-day insects, crabs and arachnids belong. This is reported by Alexander Schmidt from the University of Göttingen and his colleagues. Ambers were created from the resin of primeval trees. Most of them date back to the Cretaceous period about 130 million years ago. Therefore, most of the previously discovered trapped arthropods are representatives of this geological age. For this reason, the researchers had specifically targeted the search for inclusions in ambers that come from the Triassic: they looked into the transparent structures of a total of 70, 000 drops of amber from the Dolomites. After six years of painstaking research, the three arthropods appeared in addition to traces of microorganisms and plant remains.

Primeval tree parasites

The two mites are two different species from the group of gall mites. These arachnids still feed on plant matter today, often producing abnormal growth in the form of bile on their host plants. The fossil gall mites are surprisingly similar to today's: 230 million years ago, all the typical features were already present. "This group must therefore be much older than previously thought, " says Schmidt. Almost all today's Gallmilbenarten feed on flowering plants. However, the two primeval mites existed already 100 million years before the appearance of this group of plants. The representatives of the Triassic apparently lived as parasites on coniferous trees. "This shows that gall mites are able to exploit the prevalent plants and have developed together with their host plants, " commented co-author David Grimaldi of the American Museum of Natural History in New York.

The third amber inclusion is the trace of a two-winged insect, ie an insect. Unfortunately, a more accurate assignment is not possible because most parts of the body are not fully preserved. The fossil shows, however, that insects in unusually old amber may be included, the researchers say. In the noble stones so many more secrets could sleep. "After the largest mass extinction of the Earth's history at the end of the Permian about 250 million years ago, there were major changes in the flora and fauna in the subsequent Triassic, " explains Schmidt. For the understanding of evolution, the time of the Triassic is therefore particularly important. The amber finds can open windows into this era, say the scientists. display

Alexander Schmidt (University of Göttingen and his colleagues) et al .: PNAS, doi: 10.1073 / pnas.1208464109 © Martin Vieweg


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