This piece of amber preserved the leg of a lizard for posterity. But if you look closely, you will discover something else in the fossil resin: the fruiting bodies of a slime mold. It is a rare find.
Amber is a real time capsule: what once fell into this primeval tree sap was enclosed by it and perfectly preserved over millions of years. Again and again, amber fossils open a valuable window into the past. Researchers have already found carnivorous prehistoric plants, enigmatic insects and blood-sucking parasites in the hardened resin. Even dinosaur tails and bird wings have been discovered in amber clumps.
Now paleontologists have made another exciting discovery: They discovered the fruiting bodies of a slime mold that is around 100 million years old in a piece of amber from Myanmar. The preserved organism is one of only a few fossils of this kind – and by far the oldest.
A detailed examination of this rare fossil reveals something surprising: despite its age, the slime mold can be assigned to a genus that is still alive today. The primeval fruiting bodies can hardly be distinguished from those of modern species of the genus stemonitis. “This shows that their key features have not changed at least since the Middle Cretaceous period,” explain Jouko Rikkinen from the University of Helsinki and his colleagues. The find thus gives unique insights into the longevity of ecological adaptations of slime molds.
The slime molds, also called myxomycetes, spend most of their lives as isolated, moving cells in the ground or on rotting wood. However, the organisms can also form complex fruiting bodies that serve to form and spread spores. Although they have no brain and no nerves, some species have an astonishing amount of “brains”. For example, some slime molds can learn from experience and navigate through complex labyrinths, as experiments show.