Frozen rainforest

A trove of tiny organisms fossilized in resin, including this Phoridae fly a few millimeters long, is worth its weight in gold, say the paleontologists who found the rare bounty in the western Amazonian basin.

The insects, fungi, and plants trapped in the amber provide direct evidence that rainforests existed in the region 10 to 15 million years ago, the researchers report in an upcoming Proceedings of the National Academy of Sciences. Using light microscopy, they examined the contents of 28 amber nuggets removed from sediments of that period.

The fossils’ biodiversity is typical of that of a modern rainforest, says coauthor John J. Flynn of the American Museum of Natural History in New York City. This era “might have been when modern ecosystems were being established,” he says.