They describe an impressively intact collection of insects in an ancient amber deposit that oozed from a tropical forest in the Indian state of Gujarat. The insects are between 50 million and 52 million years old — so primeval that they're shaking up theories about the age of the oldest tropical forest and the biogeography of a continent.
Scientists believe India split off from Africa about 160 million years ago and languidly floated east for about 110 million years. When it finally smashed into Asia it raised a huge bulge — what we now know as the Himalayas.
Around that time, the northwest region that is now Gujarat was covered with a rain forest of Dipterocarpaceae, a family of tropical broadleaf trees. The excavation of the amber deposit from that forest has yielded more than 700 arthropods from 55 different genera — mostly insects, but also spiders and plants. What's unusual is that many of these species are also found in other parts of the world like Europe, Australia and even in Central America, and are not native to India alone.
Dr. Jes Rust, a paleontologist at the Universitat Bonn and a lead author of the paper, says the finding suggests India may not have been isolated at all in its drift from Africa to Asia. Instead, there may have been long chains of volcanic islands between the continental plates — similar to Japan or Indonesia today. The insect species of Asia might have made the trip to India simply by "island-hopping."
Dr. David Grimaldi, an invertebrate zoologist at the American Museum of Natural History and another author, says he was also struck by the age of the forest, especially because it's still around today.
"Here's a snapshot of a modern type of tropical forest going back 50 million years," said Grimaldi. "For a long time there's been a controversy about ages of tropical forest and this is a rare instance of insight into it."