Press release: Discovery of the earliest arthropods preserved in amber

Nr. 156/2012 - 31.08.2012

Inclusions 100 million years older than any previous finds – research led by Göttingen paleontologists

(pug) An international team of scientists led by paleontologist Dr. Alexander Schmidt of the University of Göttingen has discovered the oldest arthropods that are preserved as fossils in amber. The approximately 230 million-year-old inclusions from the Triassic Period, a diptera and two mites, were found in amber droplets only millimetres in dimensions. They come from the Italian Dolomites and are some 100 million years older than any arthropods previously detected as amber inclusions. These results have been published in the prominent journal Proceedings of the National Academy of Sciences of the USA (PNAS).

Amber is fossilised resin originating mainly from conifers. While small quantities of amber already existed in the Carboniferous Period 340 million years ago, larger deposits are only present since the Cretaceous Period around 130 million years ago. Dr. Alexander Schmidt’s group in Göttingen working at the Courant Research Centre Geobiology examined some 70,000 Triassic amber droplets for inclusions of all kinds. In addition to microorganisms and plant remains, three arthropods were found which were investigated by specialists at the American Museum of Natural History in New York, USA, and in Ottawa, Canada.

Two of these inclusions involved new species of mites, Triasacarus fedelei and Ampezzoa triassica. These are the oldest fossils of the extremely specialised Eriophyoidea group which today comprises more than 3,500 species that feed on plants and are frequently the cause of abnormal growth (‘galls’) in host plants. The gall mites from the early Mesozoic Period are surprisingly similar to those in existence today. 230 million years ago, all the characteristic features of this group were already present. “So this group must be considerably older than was thought up to now”, reports Dr. Schmidt.

The mites from the Triassic Period lived as parasites on the leaves of the trees whose resin eventually included them. Some 97 percent of today’s gall mites feed on flowering plants, yet Triasacarus and Ampezzoa lived 100 million years before this now dominant plant group appeared. “We now know that gall mites are very adaptable”, says co-author Prof. Dr. David Grimaldi, specialist on fossil arthropods at the American Museum of Natural History in New York. “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 third amber inclusion, a dipterous insect, cannot be identified with any further precision since most parts of the organism are not preserved in their entirety. But this fossil shows that insects can be present even in unusually old amber. “Following the largest mass extinction in earth’s history at the end of the Perm approximately 250 million years ago, great changes took place in the flora and fauna during the subsequent Triassic Period. This is why the Triassic Period is of particular significance in our understanding of the evolution of life on earth”, says Dr. Schmidt.

Original publication: Alexander Schmidt et al. Arthropods in amber from the Triassic Period. Proceedings of the National Academy of Sciences of the USA. Doi: 10.1073/pnas.1208464109.

Contact address:
Dr. Alexander Schmidt
Georg-August-Universität Göttingen
Courant Research Centre Geobiology
Goldschmidtstraße 3, 37077 Göttingen,
Germany
Tel.: +49 (0)551 39-7957
E-Mail: alexander.schmidt@geo.uni-goettingen.de
Internet: www.uni-goettingen.de/de/96613.html