Researchers claim to have found the first evidence of 'zombie' ants in the fossil record. They have matched peculiar cuts on a 48-million-year-old fossil leaf with the 'death bites' made by modern ants infected by a fungal parasite. The research is published today in Biology Letters1. The leaf was part of a group of fossilized leaves and plants unearthed recently from the Messel Pit in Germany's Rhine Rift Valley — an area famous for the discovery, in 2009, of Ida, a well-preserved primate fossil touted as a human ancestor (see 'Reunion of fossil halves splits scientists'). Initially, the fossil plants and leaves did not raise much interest and they were stored for years at the Smithsonian Institution's National Museum of Natural History in Washington DC.
The idea of examining the fossil record for evidence of the distinctive bite marks came to David Hughes, a behavioural ecologist at Harvard University in Cambridge, Massachusetts, as he was sitting in on a palaeobotany undergraduate course. He had just returned from fieldwork in southern Thailand where he had been studying fungal parasites infecting carpenter ants and controlling their behaviour. “Could this parasitic relationship have evolved much earlier in Earth's history?” he asked himself. So Hughes talked to Conrad Labandeira, a palaeoecologist at the Smithsonian's National Museum of Natural History. It turned out that Labandeira had seen strange markings on a fossil leaf and had been puzzled by the specimen for years. “This was a serendipitous discovery when a project on modern insect ecology crossed paths with a long-running palaeontology programme on the Messel Shale,” says Labandeira.