Madagascar copals turn out to be resin
Together with an international team, Senckenberg scientist Mónica Solórzano Kraemer examined the age and origin of the Madagascar copal. In their study, published today in the scientific journal PLOS ONE, the researchers conclude that the petrified resin has an age of no more than a few hundred years and is therefore of no paleontological relevance. However, the resins may be used to document the current species loss on the East African island.
Some of the transparent stones contain entire midge swarms, and so-called Madagascar copals are a favorite collector's item among fossil enthusiasts. "Because of these inclusions, the Malagasy 'copals' also play an important role in science," explains Dr. Mónica Solórzano Kraemer of the Senckenberg Research Institute and Natural History Museum in Frankfurt. "Over the past 20 years, dozens of scientific papers have been published on this topic, and around 120 new species were described. Surprisingly, the age and origin of the copals has never before been studied in detail."
Kraemer pursued this question together with her colleagues Xavier Delclòs (Universitat de Barcelona) and Enrique Peñalver (Instituto Geológico y Minero de España) from Spain and Voajanahary Ranaivosoa (Université d'Antananarivo) from Madagascar. The researchers set out in search of copals in three regions on the island, and subsequently dated their findings by means of the radiocarbon dating method. The results of the 14C dating came as a surprise. None of the examined specimens was older than 300 years. "Moreover, all of the resins originated from amber trees (Hymenaea) that have inhabited Madagascar since the Miocene, i.e., a time period about 5 to 23 million years ago. Yet, we were unable to find a single piece of amber or copal that dates back to this epoch," adds Solórzano Kraemer.
According to the study, the Madagascar copals and their inclusions can therefore not be used to draw conclusions about past living environments and their changes. Rather, the scientists assume that the insect species were captured and preserved in resin have an age of only a few hundred years.
"Nevertheless, the specimens have a high value—with their aid, we can detect changes in the species composition in the biodiversity hotspot of Madagascar during the past 300 years, and we can see which species have already become extinct as a result of the heavy deforestation on the island," says Solórzano Kraemer. "However, previous species descriptions from the Madagascar 'copals' must be critically checked to prevent taxonomic errors and faulty conclusions about paleontological habitats."