April 5, 2010

Ancient Amber Deposit Reveals New Insects And Bacteria

A 95-million-year-old amber deposit uncovered in Ethiopia, the first major discovery of its kind from the African continent, is helping scientists reconstruct an ancient tropical forest and gain new insights into an ecosystem once shared by dinosaurs.

The scientific team"”an international group of 20 researchers including Paul Nascimbene of the American Museum of Natural History's Division of Invertebrate Zoology"”describes the findings, which include new fungus, insects, spiders, and even bacteria from the Cretaceous Period, in the current issue of the Proceedings of the National Academy of Sciences. The amber deposit may also provide fresh insights into the rise and diversification of flowering plants during the period.

"Until now, we had discovered virtually no Cretaceous amber sites from the southern hemisphere's Gondwanan supercontinent," says Nascimbene. "Significant Cretaceous amber deposits had been found primarily in North America and Eurasia."

While some of the authors worked on the geological setting and the fossils entombed within the amber, Nascimbene, along with Kenneth Anderson from Southern Illinois University, studied the amber itself. They found that the resin that seeped from these Cretaceous Gondwanan trees is similar chemically to more recent ambers from flowering plants in Miocene deposits found in Mexico and the Dominican Republic. The amber's chemical designation is Class Ic, and it is the only Ic fossil resin discovered to date from the Cretaceous. All other documented Cretaceous ambers are definitively from non-flowering plants, or gymnosperms.

"The tree that produced the sap is still unknown, but the amber's chemistry is surprisingly very much like that of a group of more recent New World angiosperms called Hymenaea," says Nascimbene. "This amber could be from an early angiosperm or a previously-unknown conifer that is quite distinct from the other known Cretaceous amber-producing gymnosperms."

Other team members discovered 30 arthropods that had been trapped in the amber from thirteen families of insects and spiders. These fossils represent some of the earliest African fossil records for a variety of arthropods, including wasps, moths, beetles, a primitive ant, a rare insect called a zorapteran, and a sheet-web weaving spider. Parasitic fungi that lived on the resin-bearing trees were also found, as well as filaments of bacteria and the remains of flowering plants and ferns.

In addition to Schmidt, Anderson, and Nascimbene, authors include Vincent Perrichot of the Universit© Rennes in France; Norbert Vávra and Matthias Svojtka of the Universität Wien in Austria; Kebede H. Beletef of the Golden Prospect Mining Company in Ethiopia; Robert Bussert of the Technische Universität Berlin in Germany; Heinrich Dörfelt of the Friedrich-Schiller-Universität Jena in Germany; Saskia Jancke, Barbara Mohr, and Eva Mohrmann of Museum fr Naturkunde zu Berlin in Germany; Andr© Nel and Patricia Nel of Mus©um National d'Histoire Naturelle in France; Eugenio Ragazzi and Guido Roghi of University of Padova in Italy; Erin E. Saupe and Paul A. Selden of the University of Kansas in the U.S.; Kerstin Schmidt; and Harald Schneider of the Museum of Natural History in the U.K.


Image Caption: Rare Ethiopian amber deposit offers fresh insights into Cretaceous-period ecosystem. Courtesy PNAS/ Matthias Svojtka


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