Paris, April 2 : Paleontologists have found the presence of 356 animal inclusions in a 100 million years old completely opaque amber from mid-Cretaceous sites of Charentes in France.
The team of scientists, who made the discovery, is from the University of Rennes in France.
Opaque amber has always been a challenge for paleontologists. Researchers cannot study it because the naked eye cannot visualize the presence of any fossil inclusion inside. In the Cretaceous sites like those in Charentes, there is up to 80% of opaque amber.
Now, the team of paleontologists used the X-rays of the European light source to image two kilogrammes of the fossil tree resin with a technique that allows rapid survey of large amounts of opaque amber.
They applied to opaque amber a synchrotron X-ray imaging technique known as propagation phase contrast microradiography. It sheds light on the interior of this dark amber, which resembles a stone to the human eye.
"Researchers have tried to study this kind of amber for many years with little or no success. This is the first time that we can actually discover and study the fossils it contains", said ESRF paleontologist Paul Tafforeau.
The scientists imaged 640 pieces of amber from the Charentes region in southwestern France. They discovered 356 fossil animals, going from wasps and flies, to ants or even spiders and acarians.
The team was able to identify the family of 53% of the inclusions.
Most of the organisms discovered are tiny. For example, one of the discovered acarians measures 0.8 mm and a fossil wasp is only 4 mm.
"The small size of the organisms is probably due to the fact that bigger animals would be able to escape from the resin before getting stuck, whereas little ones would be captured more easily", explained paleontologist Malvina Lak.
Once discovered on the radiographs, some of the organisms were imaged in three dimensions and virtually extracted from the resin. The high quality of these 3D reconstructions enabled paleontologists to precisely study and describe the organisms.
"Opaque amber hosts many aspects of past life on our planet that are still unknown, and the use of third generation synchrotron sources will continue to play an important role in unveiling them", asserted Lak.