47-million-year Poison Mystery

Perplexed by fossils like this one of a mare with fetus, researchers questioned a long-held theory that these and other animals at a site near Frankfurt, Germany were suffocated by volcanic gases.

Perhaps one fossil would not have been enough to peak the interest of Wighart von Koenigswald, a professor at the University of Bonn, but the fact that across multiple years of the fossil record researchers found numerous dead mares and turtles lead to further investigation.

Koenigswald's team has a new theory that water supplies at the once tropical sight near Frankfurt were poisoned by a yearly algae bloom that killed the animals who drank the water. This would account for deaths at the same time of year, as observed in the fossils from Messel.

Although algal bloom poisoning has been documented in modern times finding toxic traces in animals that have been buried for 47 million years will make the theory difficult to prove.

-- Sarah Davidson

Credit: Hessian Federal State Museum Darmstad/University of Bonn