Fossile Insekten im Bernstein Amazoniens

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Thomas_
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Fossile Insekten im Bernstein Amazoniens

Beitrag von Thomas_ » Donnerstag 31. August 2006, 19:56

Der folgende Pressetext stammt vom CNRS
Quelle: http://www2.cnrs.fr/en/657.htm


Zusammenfassung:
Im norden von Peru wurden 12 bis 15 Millionen Jahre alte Fossilien von Insekten in Bernstein gefunden. Dies sind die ersten derartigen Funde im westen Amazoniens. Sie zeigen das bereits damals eine große Artenvielfalt in den warmen feuchten Wäldern existierte. Die Funde stammen aus einer einzigen Fundschicht aus dem mittleren Miozän. Ziel der mehrjährigen Forschungen ist es, die Entwicklung der Region in den letzten 20 Millionen Jahre unter dem Einfluss der Entstehung der Anden zu erforschen. Die Funddichte in diesem Bernstein war recht hoch und es konnten zahlreiche Insektenarten geborgen werden. Auch Mikrofossilien (Pollen, Algen, Sporen, Baktierien) wurden in großer Zahl gefunden. Bei einigen blieb der Inhalt der Zelle erhalten und es können eventuell DNA-Analysen vorgenommen werden, die bei der genauen Zuordnung der Arten und ihrer Entwicklungsgeschichte sehr hilfreich wären.



Discovery of fossil insects in amber from Amazonia


In northern Peru, 15 to 12 million years ago, insects, mites and other arthropods became trapped in resin on tree trunks and branches. They were discovered, fossilized in amber, by an international team of paleontologists and geologists(1). This discovery is the first of its kind in western Amazonia, and it has enabled the researchers to show that high terrestrial biodiversity existed early on in the region, in a forest environment with a hot, humid climate. These findings have been published on line on the web site of the Proceedings of the National Academy of Sciences (Consult the web site).


The amber, which is fossilized resin, comes from a single stratigraphic level dating from the middle Miocene (15 to 12 million years ago). It was discovered by the researchers on the banks of the Amazon during a field trip in the Iquitos area in 2004. The team, coordinated by Pierre-Olivier Antoine, from the Laboratory for Transfer Mechanisms in Geology (Laboratoire des mécanismes de transfert en géologie, CNRS/Université Toulouse 3/IRD), has for several years been exploring the sedimentary formations in this region, which is located at the foot of the Andes on the border of Brazil, Ecuador and Colombia. Their goal is to find out how the fauna and flora, environments and geography of western Amazonia have evolved over the past twenty million years under the influence of the uplift of the Andes. This is one of the goals of the Past Environments and Climates program (Environnements et climats du passé, ECLIPSE), a multidisciplinary program run by INSU-CNRS.

Today, Amazonia is the area with the greatest terrestrial biodiversity in the world, but very little is known about the past of this remote and little-explored region, which was totally cut off from the rest of the world 12 to 15 million years ago (the Panama isthmian strait closed up only 3.5 million years ago). The insect and arachnid fossils found by the team are the first terrestrial arthropods ever discovered in this part of the world. Amber from Amazonia contains unusually high amounts of animals and plants. At least 13 species of insect and 3 species of mite have already been identified by André Nel, a paleoentomologist from the National Museum of Natural History (Muséum National d'Histoire Naturelle, MNHN) in Paris. For instance, the fossilized resin trapped several flies and mosquitoes, parasitic wasps, a beetle related to the ladybirds, a caddis fly (well-known to anglers), and so on. There is even a mite caught up in a spider's web. A huge quantity of microfossils were trapped by the resin, including a wide range of bacteria, cyanobacteria, fungal spores, algae, and even a lichen and a pollen grain. The cell content of certain microfossils has been preserved, which means that it may be possible to access their DNA and attempt to reconstruct their phylogeny (i.e. their family tree). Thanks to this discovery, the researchers now know that 12 to 15 million years ago the region was a delta opening out into an inland sea surrounded by dense forest, with a climate that was already hot and very humid, and where it probably wouldn't have been much fun to live!

Notes :
1) The French researchers are from the Laboratory for Transfer Mechanisms in Geology (Laboratoire des mécanismes de transfert en géologie, CNRS/Université Toulouse 3/IRD), and the National Museum of Natural History (Muséum National d'Histoire Naturelle, MNHN)in Paris.

References :
Amber from western Amazonia reveals Neotropical diversity during the middle Miocene, Pierre-Olivier Antoine, Dario De Franceschi, John J. Flynn, André Nel, Patrice Baby, Mouloud Benammi, Ysabel Calderón, Nicolas Espurt, Anjali Goswami, and Rodolfo Salas-Gismondi, PNAS, on-line publication, week of 28 August 2006.

Contacts :
CNRS researcher contact
Pierre-Olivier Antoine
T 05 61 35 94 60 ou 05 61 35 94 60
poa@lmtg.obs-mip.fr

CNRS press contact
Claire Le Poulennec
T 01 44 96 49 88
Claire.le-poulennec@cnrs-dir.fr

IRD researcher contact
Patrice Baby
T 511 47 59 590 - F 511 47 54 830
Patrice.baby@ird.fr

IRD press contact
Aude Sonneville or Elodie Vignier
T 01 48 03 75 19
presse@paris.ird.fr
Dateianhänge
ambre1.jpg
This small fly, which is about 1.2 mm long, was trapped in a piece of amber from western Amazonia (Iquitos, in north-east Peru). Present-day species related to this specimen, which is between 12 and 15 million years old, feed on decomposing organic matter. We can imagine what life was like at that time in this hot, humid, dense forest.
ambre1.jpg (101.58 KiB) 10258 mal betrachtet
ambre4.jpg
Figure 2 – This small mite, which got stuck on a spider's web and then trapped in a piece of amber, is from the same deposit. The animal is less than 0.2 mm long. Notice the drop of glue on the thread at the top of the photograph.
ambre4.jpg (118.98 KiB) 10258 mal betrachtet

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