52-million-year-old beetle fossil discovered in Gujarat

The fossil was discovered from Tadkeshwar lignite mine in Gujarat by a team of scientists from Lucknow and New York

In a Jurassic Park-like discovery, scientists have chanced upon a 52-million-year-old amber encased fossil of a beetle, which thrived in ant colonies, from Gujarat providing oldest known example of social parasitism among insects, scientists here claimed today.

Termed as 'Protoclaviger trichodens' by lead researcher Joe Parker, the fossil was discovered from Tadkeshwar lignite mine in Gujarat by a team of scientists from Lucknow-based Birbal Sahni Institute of Paleobotany and American Museum of Natural History in New York.

These beetles were unique because they bypassed security in ant colonies and thrive by eating their eggs and utilising their resouces. How they do it is still being researched.

The findings published today in science journal 'Current Biology' said the fossil is the oldest-known example of this kind of social parasitism, known as "myrmecophily" where a predator lives within the colony of ants thriving on their resources and eggs.

Scientist from Birbal Sahni Institute, Hukam Singh told PTI over phone that the site from where this fossil was extracted was once a rain-forest environment where thousands of specimens were preserved in ambers giving an insight into evolution of insects and environment.

Parker said the discovery not just gives details of evolution of such beetles, but also about the ants that their nests were big enough and resource-rich enough to be worthy of exploitation by these super-specialised insects.

"And when ants exploded ecologically and began to dominate, these beetles exploded with them," a statement said.

Giving details about the finding, Parker told PTI in an email interview that the specimen was recovered from an amber deposit that marks the first appearance in the fossil record of crown group modern ant subfamilies, showing this advanced form of social parasitism is an ancient feature of modern day ants.

"Protoclaviger is transitional fossil a 'missing link' that captures an intermediate stage in the evolution of the profound morphological adaptation that enables these beetles to infiltrate ant-societies," he said.

There are 370 recorded species of these ant-loving parasite beetles, which are about 1-3 millimetres in length and escape smell-based security system of pheromones deployed by ants to identify intruders.

The intruders are immediately identified, attacked and consumed in the colonies. But the flawless security fails before parasitic Clavigeritae beetles which sneak through these defences and "integrate seamlessly" in the colony.

Despite being species rich, it is believed to be the first known fossil of the beetle which has been discovered.

The scientists suggest that although fossils shows a body which is similar to modern Clavigeritae beetles some of its characteristics are clearly more primitive.

"For example, Protoclaviger's abdominal segments are still distinct, whereas in modern beetles they are fused together into a single shieldlike segment," Parker said.