Hundreds of prehistoric insects and other creatures have been discovered in a large haul of amber excavated from a coal mine in western India. An international team of fossil hunters recovered 150kg of the resin from Cambay Shale in Gujarat province, making it one of the largest amber collections on record. The tiny animals became entombed in the fossilised tree resin some 52 million years ago, before the Indian subcontinent crunched into Asia to produce the Himalayan mountain range.
Jes Rust, a paleontologist at Bonn University, said the creatures, including ancient bees, spiders, termites, gnats, ants and flies, were in remarkably good condition considering their age. In total, the team has identified more than 700 arthropods, a group of animals that includes insects, crustaceans and arachnids.
Well preserved with details
“They are so well preserved. It's like having the complete dinosaur, not just the bones. You can see all the surface details on their bodies and wings. It's fantastic,” Rust told the Guardian . The remains of two praying mantises were also found.
Insects and other small animals may be trapped in resin flowing down tree bark, or as it covers their dead bodies on the forest floor. The resin hardens into a translucent yellow material that preserves them.
The amber is the oldest evidence scientists have of tropical forests in Asia. Tests linked the amber to a family of hardwood trees called dipterocarpaceae , that make up 80 per cent of the forest canopy in South-East Asia.
Fossilised wood from these trees was found alongside the amber deposits. Rust said that much of India may have been covered in forests at the time the amber formed.
The trapped insects give a revealing snapshot of life in India before it collided with Asia. India was once attached to Africa but separated some 160 million years ago. For the next 100 million years, India's landmass moved towards Asia at around 20 cm a year.
India was isolated for so long that it could have evolved unique flora and fauna, but the encased insects suggest this did not happen. Writing in the U.S. journal, Proceedings of the National Academy of Sciences , the team describe life forms in the amber closely related to those in Asia and Europe. As India moved towards Asia, the encroaching continental plates may have created an arc of islands that connected the two landmasses like stepping stones long before 50 million years ago, said Rust. This would allow species from India, Asia and Europe to mix.
“We think that, before the final collision between India and Asia, some sort of island arc was established. Our findings suggest that the mixing of fauna was already so strong, that it was already happening for several million years,” said Rust. Once species from India had crossed into Asia, they could have spread further, eventually reaching Australia.
Michael Engel, curator of entomology at the University of Kansas, said: “What we found indicates that India was not completely isolated, even though the Cambray deposit dates from a time that precedes the slamming of India into Asia. There might have been some linkages.” The team has so far recorded 100 different arthropod species, but Rust said they expect to find more, some of which are likely to be close relatives of animals in Africa and Madagascar. — © Guardian Newspapers Limited, 2010